Coordination chemistry of di-2-pyridylamine-based bridging
heterocyclic ligands; a structural study of coordination polymers and
discrete dinuclear complexes
Christopher J. Sumby, Peter J. Steel *
Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
________________________________________________________________________________
Abstract
Four new bridging ligands containing two di-2-pyridylamine subunits have been synthesised. The
coordination chemistry of these, along with one previously reported ligand, has been investigated
through reactions with various silver(I), copper(II) and palladium(II) reactants. Typically, reaction of
these ligands with silver(I) salts gave 1-D coordination polymers, within which the ligands act as
divergent bridging units, while reaction with copper(II) and palladium(II) precursors provided
discrete dinuclear complexes with chelating bidentate subunits. The complexes were characterised
by a combination of elemental analysis, NMR spectroscopy and X-ray crystallography. The silver
coordination polymers displayed interesting variations in supramolecular architecture, attributed to
weak secondary interactions, such as Ag···-bonding.
Keywords: N-ligand; Bridging ligand; Silver; X-ray diffraction; -interactions
____________________________________________________________________
* Corresponding author. Tel.: +64-3-3642432 Fax: +63-3-3642110
Email address: peter.steel@canterbury.ac.nz
1. Introduction
Over the last decade infinite one-, two-, and three-dimensional (1-, 2-, and 3-D) networks have
been the focus of significant attention [1]. In particular, coordination polymers, in which transition
metal ions (M) are linked together by bridging organic ligands (L), have been at the forefront of this
research because of their robust nature, interesting structural features, topologies and properties, and
their potential application as functional materials [1g-1m]. In addition to the control the M-L
coordinate bonding exerts on the types of network structures formed, weaker interactions, such as
hydrogen bonding and - stacking interactions, often play a significant role in the formation of
these coordination polymers [2].
Multifunctionalised arene precursors provide ideal platforms upon which a range of heterocyclic
donors can be appended to provide diverse bridging ligands [3]. Several research groups [4,5],
including ourselves [3,6], have previously exploited various arene cores in the preparation of a
library of multidentate bridging ligands, generalised by the structure shown in Figure 1(a). In such
ligands, the central arene core, represented by a benzene ring in the schematic, may be a number of
different aromatic ring systems, including benzene [6], naphthalene [7], anthracene [8], or even
another heterocycle that can provide further donor atoms [9]. The linker atom or spacer group (X)
can be varied by changing both the type of atoms and the length of the spacer, allowing control over
the flexibility of the ligand [4d,6c,10]. The heterocyclic group appended to the arm can also be
varied, with a range of possibilities including, for example, pyridine, pyrazole and more recently
quinoline [6a,11]. Finally, the number of groups (n), which are appended to the central ring system,
can be altered.
[Figure 1 here]
We sought to extend this work by incorporating symmetrical chelating groups onto a central
arene core, as represented by the schematic diagram in Figure 1(b), in order to induce more stable
complexation due to the chelate effect. Ligands that conform to this representation have recently
been reported by Kim [12], Wang [4b.4g,4h,13,14], Reedijk [4i-4k,15], Meyer [4l,4m], Ward [5]
and ourselves [16]. These have been shown to lead to both discrete and polymeric coordination
compounds some of which have interesting chemical and physical properties. We now report the
incorporation of di-2-pyridylamine (1) as the chelating subunit in several such ligands. Specifically,
we describe new complexes of the known ligand (2) [17] and the four new ligands (3-6), each of
which contains two di-2-pyridylamine substituents directly attached to either a benzene or
naththalene core. The metal reactants chosen for study were silver(I) salts (for 2-, 3- or 4coordination), which were expected to lead to coordination polymers that are the subject of much
current interest [18], copper(II) nitrate (for 5- or 6-coordination) and palladium(II) chloride (for
square-planar 4-coordination), which were expected to form discrete molecular complexes with
potentially interesting physicochemical properties. This manuscript describes the syntheses and
crystallographic characterisation of these ligands and complexes.
2. Results and discussion
2.1. Ligand syntheses
The ligands were prepared either by a copper-catalysed Ullmann coupling procedure [19], where
the appropriately substituted aryl bromide was reacted with di-2-pyridylamine, or by a route in
which aryl primary diamines were coupled to four equivalents of 2-bromopyridine, using the
palladium-catalysed amination chemistry of Buchwald and Hartwig [20,21]. The previously reported
ligand 1,4-bis(di-2-pyridylamino)benzene (2) was prepared by the literature procedure utilising the
Ullmann coupling reaction [17]. This methodology was extended to the synthesis of 1,4-bis(di-2pyridylamino)naphthalene (4), which differs only in the fusion of an extra benzene ring to the core
of the ligand. Using similar experimental conditions to those reported for the synthesis of 2, this new
ligand could not be prepared from 1,4-dibromonaphthalene (7) in a single step, even after prolonged
reaction times. Instead it was synthesised by a two step process in which the mono-substituted
compound (8) was prepared, as shown in Scheme 1, and then further reacted under identical
conditions to give 4. Although the yields for these two reactions were relatively low, the simplicity
of the chemistry meant that ample material was easily prepared for an investigation of the
coordination and metallosupramolecular chemistry.
[Scheme 1 here]
In view of the low yields in the above reactions, another method was sought for the syntheses of
the remaining ligands. Palladium-catalysed amination of heterocycles has been extensively studied
and reviewed [20,21]. Based on these reports, a [Pd2(dba)3]/BINAP catalyst system was employed
for the synthesis of 1,5-bis(di-2-pyridylamino)naphthalene (5) by amination of 2-bromopyridine
with the appropriate diaminonaphthalene, as shown in Scheme 1. While the reaction conditions were
not optimised, the synthesis of 5 proceeded in 54% yield. Using the same methodology, ligands 3
and 6 were prepared in 48% and 50% yield, respectively. These new ligands were all characterised
by NMR spectroscopy, mass spectrometry and elemental analysis.
2.1.1. Crystal structure of 5
Ligand 5 crystallises in the monoclinic space group P21/n with half a molecule in the asymmetric
unit. It was anticipated that 5 would pack in a relatively flat conformation in the solid state, with
slight twists of the pyridine rings to relieve steric hindrance between the H3 protons of the pyridine
ring and the arene core. Instead, the di-2-pyridylamine units twist almost perpendicular to the
naphthalene core [torsion angles of 103.2(3) and 108.3(3)º], as shown in Figure 2, and adopt a
similar conformation to that of a biphenyl analogue described by Wang and co-workers [17]. One
pyridine ring on each arm of the ligand twists away to relieve the lone-pair repulsion between the
nitrogen atoms. The pyridine rings of adjacent molecules of 5 pack on either face of the naphthalene
ring, within the cavity formed by pairs of pyridine rings. This packing arrangement is reinforced by
weak C-Hnaph···Npy interactions (2.860 Å) and edge-to-face C-Hpy··· interactions (C-Hpy···pycentroid
distance 2.538 Å; Cpy···pycentroid distance 3.440 Å) between adjacent pyridine rings.
[Figure 2 here]
2.2. Synthesesof complexes
Discrete dinuclear praseodynium and europium complexes of the previously reported ligand, 2,
have been prepared and characterised by Wang et al. [17]. We have now investigated the
coordination chemistry of 2 by reaction with silver nitrate, silver tetrafluoroborate, silver
hexafluorophosphate, copper nitrate and palladium chloride.
Reaction of two equivalents of silver nitrate with 2 provided a complex (9) with 1:1 metal-ligand
stoichiometry, as determined by elemental analysis (Scheme 2). Such a composition suggested that 9
was likely to be either a discrete [2+2] dimer or polymeric in nature. Fortunately, colourless crystals
were obtained directly from the reaction mixture and these were suitable for X-ray crystal structure
analysis. Reaction of 2 with silver tetrafluoroborate also gave colourless crystals by slow
evaporation of the acetonitrile reaction medium. This second silver complex (10) was characterised
by elemental analysis and X-ray crystallography revealing a 2:1 metal-ligand stoichiometry. These
two contrasting structures are described below. The reaction of 2 with silver hexafluorophosphate
resulted only in the formation of black decomposition products and was not pursued.
[Scheme 2 here]
Reacting ligand 2 with palladium chloride and copper nitrate gave two dinuclear complexes, 11
and 12, respectively. Complex 11 was obtained as a bright yellow solid by combining a solution of
palladium chloride in 2 M hydrochloric acid with a solution of 2 dissolved in methanol. This
compound gave an elemental analysis consistent with a discrete dinuclear complex, [(PdCl2)2(2)],
but was insoluble in common NMR solvents and no further characterisation was undertaken. The
copper nitrate complex (12) was isolated as a green solid from the methanol reaction medium and
small green crystals, suitable for crystal structure analysis, were subsequently obtained by vapour
diffusion of acetone into a DMSO solution of the complex. Elemental analysis was consistent with a
dinuclear complex, [{Cu(NO3)2}2(2)].CH3OH.
To investigate the various possible coordination modes of the closely related ligand, 3, which
possesses a meta arrangement of the chelating subunits, it was reacted with a similar range of
transition metal reagents. Combining acetonitrile solutions of the ligand and silver nitrate gave a
complex (13) with an elemental analysis corresponding to [(AgNO3)2(3)]. A number of structures are
possible for such a composition, but fortunately crystals were obtained which were suitable for Xray crystallography. Interestingly, a second silver complex (14) with an identical metal-ligand
composition was obtained by reaction of the same ligand with silver hexafluorophosphate. The
structures of both these complexes are described below. With copper nitrate and palladium chloride
two dinuclear complexes, 15 and 16, were obtained in 59% and 62% yields, respectively. These
analyse as [{Cu(NO3)2}2(3)] and [(PdCl2)2(3)].CH3OH.H2O. Complex 15 was recrystallised by
vapour diffusion of diethyl ether into a methanol solution of the compound to provide crystals that
were characterised by X-ray crystallography. Unfortunately, 16 was insoluble in common NMR
solvents and was not further characterised.
Ligand 4 was also reacted with silver nitrate and silver tetrafluoroborate, but no readily
characterisable products were isolated. However, reacting silver hexafluorophosphate with 4 gave a
complex (17) which was isolated as a colourless crystalline solid in 85% yield (Scheme 2).
Elemental analysis revealed a M2L composition of the bulk sample of 17a. However, the crystals
obtained, as a minor component (17b) by slow evaporation of the filtrate, had a different
composition and were shown by X-ray crystallography to be composed of a discrete [2+2] metalligand dimer. Following reaction with copper nitrate, a complex (18) was isolated that analysed as
[{Cu(NO3)2}2(4)], but which unfortunately, despite repeated attempts, could not be crystallised. A
further dinuclear complex (19) was obtained by reaction of the ligand dissolved in methanol with
palladium chloride dissolved in 2M hydrochloric acid. Elemental analysis confirmed the
composition as [(PdCl2)2(4)], but unfortunately, this palladium complex was also insoluble in
common NMR solvents and was not further characterised.
The naphthalene-based ligands, 4, 5, and 6, are less soluble in polar solvents than those
containing benzene cores. This necessitated special considerations regarding reaction conditions for
the formation of complexes, especially for ligand 5, the least soluble of the three compounds. Using
labile metals like silver, the methods of preparing and/or recrystallising complexes, which had been
successful for the other ligands, failed to provide crystalline complexes of 5. In most cases the ligand
precipitated in preference to a complex. However, with copper nitrate a dinuclear complex (20),
which analyses as [{Cu(NO3)2}2(5)].1½CH2Cl2 was isolated in 62% yield, by vapour diffusion of
diethyl ether into the methanol-dichloromethane reaction mixture. A palladium chloride complex
(21) was also obtained by the usual procedure in 78% yield. This complex is also dinuclear and
analyses as [(PdCl2)2(5)].H2O.
Ligand 6, which incorporates a 2,7-disubstituted naphthalene core, might be expected to lead to
complexes closely related to those of ligand 3, but with potentially increased metal-metal separations
because of the greater size of the central naphthalene core. Reaction of 6 with silver tetrafluoroborate
and silver hexafluorophosphate gave complexes 22 and 23, respectively, which had almost identical
structures when characterised by X-ray crystallography. Of these, complex 22, which was obtained
in 62% yield, will be described in detail because the structure refined to a more satisfactory level.
This complex was recrystallised by vapour diffusion of diethyl ether into an acetonitrile solution,
and analyses with a 2:1 metal-ligand ratio.
Reaction of copper nitrate with a solution of 6 dissolved in methanol gave a green dinuclear
copper complex (24) in 52% yield. The complex analyses as [{Cu(NO3)2}2(6)].2CH3OH indicating
that the complex is likely to have a very similar structure to that of complex 15. Reacting the same
ligand with palladium chloride in 2M hydrochloric acid immediately led to a yellow precipitate in
91% yield, which gave an elemental analysis consistent with [(PdCl2)2(6)].H2O (25). Pleasingly,
complex 25 was soluble in DMSO and was confirmed to be the symmetrical dinuclear complex by
1
H NMR. The 1H NMR chemical shifts and coordination-induced-shift values (CIS = complex - ligand)
for complex 25 are shown in Table 1. The downfield shifts of the pyridine signals are consistent with
coordination to the pyridine nitrogen atoms, and the high symmetry of the 1H NMR spectrum
confirms that the ligand chelates to two palladium atoms, with a doubly bidentate bridging
coordination mode.
2.3. Crystal structures of silver complexes
2.3.1. Structure of 9
The overall structure of complex 9, [AgNO3(2)]n, is a 1-D zig-zag coordination polymer
consisting of a 1:1 ratio of metal and ligand. It crystallises in the triclinic space group P-1, with two
half ligand components, one silver atom and a coordinated nitrate anion in the asymmetric unit
(Figure 3). The two independent ligands each lie on a centre of inversion, located at the centroids of
the benzene rings. Each ligand molecule coordinates to two symmetry-related silver atoms, which
also have a coordinated nitrate anion giving the silver a distorted trigonal-planar coordinate
geometry. Each ligand molecule acts in a hypodentate manner with only two of the four pyridine
rings involved in coordination.
[Figure 3 here]
As Figure 4 illustrates, the extended structure is a 1-D zig-zag coordination polymer. Relatively
short distances of 6.832 and 6.955 Å separate adjacent silver atoms because the coordinated pyridine
rings twist back toward the central arene core of the ligand allowing the silver atoms to interact with
the central benzene core. 1 or 2-Ag···-interactions further shield the silver atom, although the
shortest Ag-C distances are 2.965 and 3.040 Å to adjacent benzene rings, indicating that these are
very weak interactions. The average distance for similar interactions is ca. 2.8 Å [1d,22], which are
typically in the range 2.4-2.9 Å [23] and the present values are thus outside the range normally
considered as bonding. However, they undoubtedly shield the Ag centre from further coordination.
There are no unusually short intermolecular contacts between adjacent 1-D polymer chains.
[Figure 4 here]
2.3.2. Structure of 10
The structure of complex 10, of composition [Ag2(2)(CH3CN)2](BF4)2, is also a 1-D coordination
polymer, but in contrast to 9, posseses a 2:1 metal to ligand stoichiometry. The asymmetric unit of
this compound, which crystallises in the space group C2/c, is shown in Figure 5. It consists of half a
molecule of ligand 2, two half occupied silver atoms that lie on a 2-fold rotation axis, a coordinated
acetonitrile and a disordered tetrafluoroborate anion. The two silver atoms have very different
coordination environments; Ag1 has a linear two-coordinate geometry with a comparatively short
Ag-N distance to two symmetry related pyridine nitrogens, whereas Ag2 has a distorted squareplanar geometry with considerably longer Ag-N distances to two pyridine and two acetonitrile
ligands.
[Figure 5 here]
An extended view of the structure shows that each molecule of ligand 2 coordinates to four
different silver atoms to form an unusual 1-D coordination polymer with a pronounced zig-zag shape
(Figure 6). The ligand molecules lie approximately perpendicular to the direction of propagation of
the polymer chain, and are connected through 12-membered dimetallocycles formed from two silver
atoms and the di-2-pyridylamine subunits of two ligand molecules. The coordinated acetonitrile
molecules occupy the cavities between the benzene rings of adjacent ligands.
[Figure 6 here]
There are several unusual and interesting features of this structure. The Ag2 silver atom has a
relatively unusual square-planar geometry, with four-coordinate silver generally preferring
tetrahedral geometries [24]. However, when weaker interactions with the metal centre are
considered, the silver can be viewed as having a pseudo-octahedral geometry, with weak 1-Ag···interactions provided by the benzene rings on either side of Ag2. The Ag-C distance is 2.975 Å to
the electron rich C1 and C4 carbon atoms of the proximate benzene rings. A 2,2’-bipyridine ligand
has recently been shown to induce a similar planar silver geometry, but with even weaker Ag-C
interactions [25]. The linear coordination geometry of Ag1 is also complemented by similar
interactions from the surrounding pyridine rings. The shortest Ag-C distance is 2.831 Å to the C2
position of the adjacent pyridine ring. This latter interaction is well within the range reported for
other 1-Ag···-interactions in the literature [23]. The contrasting distances for the 1-Ag···interactions for the linear Ag1 and the square planar Ag2 are reflective of their differing
coordination numbers; Ag2 is more coordinatively saturated and thus the 1-Ag···-interaction is
necessarily weaker.
There are three unique silver-silver distances [Ag1…Ag2 = 4.324, Ag2…Ag2 = 6.442, Ag1…Ag1
= 11.387 Å], none of which involves direct bonding interactions. The coordination polymer
propagates along the c-axis of the unit cell with the non-coordinated tetrafluoroborate anions filling
the voids between the polymers. The coordinated acetonitrile molecules protrude out of the polymer
and the methyl groups make weak contacts with the fluoride atoms of the tetrafluoroborate anions.
These C-H···F hydrogen bonding interactions have H-F distances in the range 2.380 - 2.423 Å,
which is similar to other reported examples [26], and less than the sum of the van der Waals radii for
H and F atoms of 2.54 Å [27].
2.3.3. Structures of 13 and 14
The structures of both 13 and 14 will be described together because they have the same overall
coordination framework, but with different anions and solvate compositions. Complex 13
crystallises in the primitive space group P21/n and complex 14 in the C-centred monoclinic space
group Cc. Focussing on structure 14, the large asymmetric unit contains four silver atoms, two
molecules of 3, six coordinated acetonitrile molecules, two non-coordinated acetonitrile solvate
molecules, a non-coordinated diethyl ether molecule and four non-coordinated hexafluorophosphate
anions (Figure 7). The structure has a pseudo-inversion centre at the centroid of the dimetallocycle,
but this higher symmetry is destroyed by the solvate molecules.
[Figure 7 here]
The coordination geometry of Ag1 and Ag2 is distorted T-shaped, while the central silver atoms,
Ag3 and Ag4, have pseudo-octahedral geometries, with two coordinated pyridine rings, two
coordinated acetonitrile molecules and weak 1-Ag···-interactions from adjacent benzene and
pyridine rings. The extended structure of 14 is an undulating 1-D coordination polymer, with each
ligand molecule involved in forming two different 12-membered dimetallocyclic rings, with silversilver separations of 5.054 Å between Ag3 and Ag4 and 3.976 Å between Ag1 and Ag2. The overall
metal-ligand connectivity of 14 is closely related to structure 10. However, because of the
differences in silver geometries and in the ligand substitution pattern, the overall structures of the 1D coordination polymers are quite different. Schematic representations of the two different types of
[M2L]n coordination polymers observed with ligands 2 and 3 are shown in Figure 8. The change
from a 1,4-disubstituted benzene core in ligand 2, to the 1,3-arrangement in ligand 3, results in silver
complexes with the same connectivity, but with different overall topologies. Two related copper
structures are described below which serve to highlight the consistent behaviour of these two
ligands.
[Figure 8 here]
As outlined above, a very similar complex, (13), was obtained by reaction of 3 with silver nitrate.
In this structure, the asymmetric unit of which is shown in Figure 9, the nitrate anions coordinate in
the positions that were occupied by coordinated acetonitrile molecules in complex 14 such that the
nitrate anion chelates to the Ag centre when replacing two acetonitrile ligands and acts as a
monodentate donor when replacing only one molecule. The coordination environment of all four
silver atoms is very similar to that described for complex 14. No unusually short intermolecular
interactions exist between the individual 1-D coordination polymers within these structures.
[Figure 9 here]
2.3.4. Structure of 17b
The plate-like crystals of 17b crystallise in the monoclinic space group P21/c with two Ag2L2
metallomacrocycles in the unit cell. The asymmetric unit comprises one molecule of 4, one silver
atom, one coordinated and two non-coordinated acetonitrile solvate molecules, and a noncoordinated hexafluorophosphate anion. A perspective view of the Ag2L2 metallomacrocycle is
shown in Figure 10. The silver atom has a distorted trigonal-planar geometry with bond lengths and
angles typical for such a complex. In forming the discrete [2+2] dimer the nitrogen donors of the
ligands are complemented by weak arene C-H agostic interactions between the non-coordinated
pyridine and the silver. The metal-metal distance is 10.679 Å and not significantly different to other
complexes of ligand 2, which has an arene core of identical length. A structurally related silver
trifluoroacetate complex has recently been described by Kang et al. using 4,4’-bis(di-2pyridylamino)diphenylacetylene, a ligand with a rod-like structure [28].
[Figure 10 here]
2.3.5. Structure of 22.3MeCN
Complex 22 crystallises in the monoclinic space group P21/c, with one molecule of 6, two silver
atoms, three coordinated acetonitrile solvate molecules (one of which is disordered over two sites)
and three tetrafluoroborate anions (two 50% occupied) in the asymmetric unit. One of the tetrahedral
tetrafluoroborate anions appears to be disordered over an octahedral site. A perspective view of the
asymmetric unit is shown in Figure 11, with non-coordinated anions omitted for clarity. The
coordination environment of Ag1 has an unusual trigonal-pyramidal geometry when only the
symmetry-related pyridine donors and the two acetonitrile molecules are considered. However, when
an 1-Ag···-interaction (2.991 Å) is considered, the geometry of Ag1 can be described as trigonalbipyramidal. The acetonitrile molecule with the nitrogen atom labelled N71, is disordered over two
sites with occupancies of 62.5% and 37.5%. Ag2 has a similar five-coordinate geometry when the
1-Ag···-interactions are taken into account. Ag2 coordinates to two pyridine rings, one acetonitrile
molecule and makes two 1-Ag···-interactions with Ag-C distances of 2.721 and 2.964 Å. The
former Ag-C distance is to the naphthalene ring of a symmetry-related ligand molecule, while the
latter distance is to C2 of the adjacent pyridine ring (the nitrogen atom of this pyridine ring is
labelled N31). The shortest silver-silver distance in the structure, between Ag1 and Ag2, is 4.461(1)
Å, indicating there are no direct silver-silver interactions within this coordination polymer.
[Figure 11 here]
The extended structure of 22 is a 1-D M2L coordination polymer with a similar connectivity to
some of the structures described above. Each ligand is bonded to two silver atoms, which are part of
a 12-membered dimetallocycle, as was observed in complexes 10, 13 and 14. A diagram showing the
connectivity and a simplified representation of the 1-D coordination polymer 22 is shown in Figure
12.
[Figure 12 here]
2.4. Crystal structures of copper complexes
2.4.1. Structure of 12.2DMSO
The structure of 12 is a discrete dinuclear complex, which crystallises about a centre of inversion
in the triclinic space group P-1, as shown in Figure 13. The asymmetric unit contains half a molecule
of 2, a copper atom, two coordinated nitrate anions and a coordinated dimethyl sulfoxide (DMSO)
molecule. The copper atom has a geometry best described as square-pyramidal, with a  value of
0.21 [29]. The nitrate oxygen, O51, is in the apical coordination site with a Cu-O distance of
2.235(6) Å. The ligand uses all its potential donor atoms in this complex, in contrast to the first
silver complex (9), where the ligand is hypodentate. The copper-copper separation in this complex is
11.179 Å, and considerably longer than the silver-silver distance in complex 9, because the pyridine
donors are directed away from the centre of the bridging ligand.
[Figure 13 here]
2.4.2. Structure of 15.2MeOH
Crystals of a second discrete dinuclear copper complex (15) were obtained by vapour diffusion
of diethyl ether into a methanol solution of the complex formed from ligand 3. The complex
crystallises in the monoclinic space group C2/c, with half the dinuclear complex in the asymmetric
unit (Figure 14). A two-fold rotation axis passes through C2 and C5 of the central benzene ring. The
copper atom has a distorted square-pyramidal geometry ( = 0.19) with the coordinated methanol
molecule bonded in the apical position. The bond lengths to the copper are typical for such a
geometry. Like previous structures of these ligands, the chelating units are twisted approximately
perpendicular to the benzene ring. The ligand bridges the two copper atoms with a metal-metal
distance of 8.785 Å, which is considerably shorter than in the copper complex 12 involving ligand 2.
[Figure 14 here]
3. Experimental
3.1. General
Melting points were recorded on an Electrothermal melting point apparatus and are uncorrected.
The Campbell microanalytical laboratory at the University of Otago performed elemental analyses.
Electrospray (ES) mass spectra were recorded using a Micromass LCT-TOF mass spectrometer.
NMR spectra were recorded on a Varian 500 MHz spectrometer at 23C, using a 3 mm probe.
Unless otherwise stated, reagents were obtained from commercial sources and used as received. The
following compounds were prepared by literature procedures: 1,4-bis(di-2-pyridylamino)benzene
[17], dibenzylideneacetone (dba) [30], tris(dibenzylideneacetone)dipalladium(0), [Pd2(dba)3] [31].
3.2. Preparation of ligands
3.2.1. 1,3-Bis(di-2-pyridylamino)benzene (3)
To a suspension of 1,3-diaminobenzene (176 mg, 1.63 mmol), potassium t-butoxide (852 mg,
7.59 mmol), rac-BINAP (152 mg, 0.24 mmol), [Pd2(dba)3] (112 mg, 0.12 mmol) in dry toluene (28
mL) was added 2-bromopyridine (720 L, 7.55 mmol). This mixture was heated at 80C for 96
hours. After cooling, ethyl acetate was added, the insoluble material removed by filtration and the
filtrate was evaporated to dryness in vacuo. The residue was purified by chromatography on silica
gel using 1:9 methanol-dichloromethane eluent to give 3. Yield 325 mg (48%). M.p. 133-136C.
HRMS: calc. for C26H21N6+ 417.1822; found 417.1828. 1H NMR (CDCl3)  8.30 (d, J = 4.9 Hz, 4H,
H6’), 7.54 (td, J = 7.8, 2.0 Hz, 4H, H4’), 7.33 (t, J = 8.4 Hz, 1H, H5), 7.05 (d, J = 8.3 Hz, 4H, H3’),
6.99 (m, 3H, H2, H4/H6), 6.90 (dd, J = 7.3, 4.9 Hz, 4H, H5’).
145.9, 137.5, 130.5, 125.3, 123.4, 118.3, 117.1.
13
C NMR (CDCl3)  157.7, 148.3,
3.2.2. 1-Bromo-4-(di-2-pyridylamino)naphthalene (8)
1,4-Dibromonaphthalene (2.86 g, 10 mmol), di-2-pyridylamine (3.42 g, 20 mmol), potassium
hydroxide (1.46 g) and copper(II) sulfate (100 mg) were heated at 180C for 24 hours. After cooling,
water was added to the residue which was extracted with dichloromethane. The chlorinated organic
layer was washed with water until the washings were neutral, dried over magnesium sulfate and the
solvent removed in vacuo. Chromatography on alumina with dichloromethane gave the product as a
white solid. Yield 1.15 g (31%). M.p. 136-139C. ES-MS 378.0 and 376.0 [(M+1)]+.1H NMR
(CDCl3)  8.28 (m, 3H, H6’, H8), 7.88 (d, J = 8.8 Hz, 1H, H5), 7.85 (d, J = 7.8 Hz, 1H, H2), 7.57 (t,
J = 8.3 Hz, 1H, H7), 7.51 (t, J = 8.3 Hz, 2H, H4’), 7.41 (t, J = 7.6 Hz, 1H, H6), 7.32 (d, J = 7.7 Hz,
1H, H3), 6.96 (2H, J = 8.3 Hz, d, H3’), 6.89 (dd, J = 7.0, 4.9 Hz, 2H, H5’).
13
C NMR (CDCl3) 
157.9, 148.3, 141.0, 137.5, 133.5, 132.7, 130.4, 128.0, 127.9, 127.62, 127.58, 124.2, 122.1, 117.8,
115.7.
3.2.3. 1,4-Bis(di-2-pyridylamino)naphthalene (4)
1-Bromo-4-(di-2-pyridylamino)naphthalene (620 mg, 1.65 mmol), di-2-pyridylamine (340 mg, 2
mmol), potassium hydroxide (200 mg) and copper(II) sulfate (10 mg) were heated at 180C for 48
hours. After cooling, water was added to the residue which was extracted with dichloromethane. The
chlorinated organic layer was washed with water until the washings were neutral, dried over
magnesium sulfate and the solvent removed in vacuo. Chromatography on alumina, with
dichloromethane as the eluent, gave 4 as a yellow solid that was recrystallised from
dichloromethane-diethyl ether. Yield 254 mg (33%). M.p. 247-249C. Analysis: calc. for
C30H22N6.¼H2O (471.04) C 76.49, H 4.81, N 17.84; found C 76.56, H 4.61, N 18.10%. HRMS: calc.
for C30H23N6+ 467.1984; found 467.1986. 1H NMR (CDCl3)  8.30 (d, J = 4.9 Hz, 4H, H6’), 7.92
(dd, J = 6.8, 2.9 Hz, 2H, H5/H8), 7.53 (m, 6H, H4’, H2/H3), 7.33 (dd, J = 6.6, 2.9 Hz, 2H, H6/H7),
7.01 (d, J = 8.5 Hz, 4H, H3’), 6.90 (dd, J = 6.8, 4.9 Hz, 4H, H5’). 13C NMR (CDCl3)  158.0, 148.2,
140.3, 137.5, 133.0, 128.1, 127.1, 124.4, 117.8, 116.0.
3.2.4. 1,5-Bis(di-2-pyridylamino)naphthalene (5)
To a suspension of 1,5-diaminonaphthalene (127 mg, 0.80 mmol), potassium t-butoxide (426
mg, 3.80 mmol), R-(+)-BINAP (38 mg, 0.06 mmol), [Pd2(dba)3] (28 mg, 0.03 mmol) in dry toluene
(14 mL) was added 2-bromopyridine (360 L, 3.76 mmol). The resulting reaction mixture was
heated at 80C for 96 hours. After cooling, ethyl acetate was added, the insoluble material removed
by filtration and the filtrate was evaporated to dryness in vacuo. The residue was triturated in hot
ethanol and cooled to give 5 as a brown solid, which was subsequently recrystallised from
dichloromethane-diethyl ether. Yield 200 mg (54%). M.p. 281-283C. Analysis: calc. for C30H22N6
(466.54) C 77.23, H 4.75, N 18.01; found C 77.34, H 4.69, N 17.93%. HRMS: calc. for C30H23N6+
467.1984; found 467.1989. 1H NMR (CDCl3)  8.30 (d, J = 4.0 Hz, 4H, H6’), 7.90 (d, J = 7.9 Hz,
2H, H4/H8), 7.53 (t, J = 7.3 Hz, 4H, H4’), 7.43 (m, 4H, H2/H6, H3/H7), 6.98 (d, J = 8.3 Hz, 4H,
H3’), 6.90 (t, J = 5.9 Hz, 4H, H5’).
13
C NMR (CDCl3)  158.2, 148.3, 141.6, 137.5, 133.4, 128.0,
127.2, 123.5, 117.8, 116.1.
3.2.5. 2,7-Bis(di-2-pyridylamino)naphthalene (6)
2,7-Diaminonaphthalene (254 mg, 1.61 mmol), potassium t-butoxide (856 mg, 7.63 mmol), racBINAP (152 mg, 0.24 mmol) [Pd2(dba)3] (112 mg, 0.12 mmol) were suspended in dry toluene (28
mL). 2-Bromopyridine (720 L, 7.55 mmol) was added and the reaction mixture stirred at 80C for
96 hours. After cooling, ethyl acetate was added, the insoluble material removed by filtration
through a Celite plug before the filtrate was chromatographed on silica gel using 1:9 methanoldichloromethane as an eluent. Recrystallisation from acetone-water gave 6 as a pale brown solid.
Yield 375 mg (50%). M.p. 197-199C. Analysis: calc. for C30H22N6.½H2O (475.55) C 75.77, H 4.87,
N 17.67; found C 75.98, H 4.68, N 17.50%. HRMS: calc. for C30H23N6+ 467.1984; found 467.1983.
1
H NMR (CDCl3)  8.31 (dd, J = 4.9, 1.5 Hz, 4H, H6’), 7.81 (d, J = 8.8 Hz, 2H, H4/H5), 7.56 (td, J
= 7.8, 2.0 Hz, 4H, H4’), 7.46 (d, J = 2.0 Hz, 2H, H1/H8), 7.26 (dd, J = 7.8, 2.0 Hz, 2H, H3/H6), 7.02
(d, J = 8.3 Hz, 4H, H3’), 6.93 (dd, J = 7.8, 4.9 Hz, 4H, H5’).
13
C NMR (CDCl3)  158.0, 148.5,
143.0, 137.5, 135.3, 129.4, 129.2, 125.7, 124.1, 118.3, 117.2.
3.3. Preparation of complexes
3.3.1. Complexes of 2
3.3.1.1. [AgNO3(2)] n (9)
Ligand 2 (20.0 mg, 0.048 mmol) and silver nitrate (15.9 mg, 0.093 mmol) were separately
dissolved in hot acetonitrile, the solutions combined and allowed to cool. Crystalline material
precipitated overnight, which contained crystals suitable for X-ray crystallography. Yield 22 mg
(78%). M.p. 235C (dec.). Analysis: calc. for C26H20N7O3Ag (586.35) C 53.26, H 3.44, N 16.72;
found C 53.56, H 3.53, N 16.87%.
3.3.1.2. {[Ag2(2)(CH3CN)2](BF4)2}n (10)
Ligand 2 (20.0 mg, 0.048 mmol) and silver tetrafluoroborate (21.1 mg, 0.108 mmol) were each
dissolved in hot acetonitrile, the solutions combined and allowed to slowly evaporate. Small platelike crystals were obtained, which were suitable for X-ray crystallography. Yield 34 mg (76%). M.p.
>120C (dec.).
3.3.1.3. [(PdCl2)2(2)] (11)
Palladium chloride (17.1 mg, 0.096 mmol) was dissolved in 2M hydrochloric acid (2 mL) and
added slowly to a hot methanolic solution of 2 (20.1 mg, 0.048 mmol). The solution turned yellow
and a fine yellow solid precipitated. After heating for 30 minutes, the precipitate was collected by
filtration and dried in vacuo. Yield 34 mg (92%). M.p. >330C. Analysis: calc. for C26H20N6Cl4Pd2
(771.13) C 40.50, H 2.61, N 10.90; found C 40.50, H 2.69, N 10.76%. The complex was insoluble in
common NMR solvents.
3.3.1.4. [{Cu(NO3)2}2(2)].CH3OH (12.CH3OH)
Ligand 2 (20.2 mg, 0.043 mmol) and copper nitrate (25.1 mg, 0.104 mmol) were each dissolved
in methanol and combined. Slow evaporation of the resulting solution gave a green precipitate. Yield
32 mg (83%). M.p. >282ºC (dec.). Analysis: calc. for C26H20N10O12Cu2.CH3OH (823.63) C 39.37, H
2.94, N 17.01; found C 39.85, H 2.90, N 17.12%. Crystals, suitable for X-ray crystallography, were
obtained by vapour diffusion of acetone into a DMSO solution of the complex.
3.3.2. Complexes of 3
3.3.2.1. [(AgNO3)2(3)] n (13)
Ligand 3 (20.0 mg, 0.048 mmol) and silver nitrate (17.9 mg, 0.106 mmol) were each dissolved in
hot acetonitrile, the solutions combined and allowed to cool. Vapour diffusion of diethyl ether into
the reaction mixture gave crystals suitable for X-ray crystallography. Yield 23.2 mg (63%). M.p.
169-171C. Analysis: calc. for C26H20N8O6Ag2 (756.22) C 41.29, H 2.67, N 14.82; found C 41.41, H
2.72, N 14.27%.
3.3.2.2. {[Ag2(3)](PF6)2}n (14)
Ligand 3 (20.0 mg, 0.48 mmol) and silver hexafluorophosphate (27.3 mg, 0.107 mmol) were
dissolved in hot acetonitrile. The solid obtained after evaporation of the resulting solution was
recrystallised by vapour diffusion of diethyl ether into an acetonitrile solution of the complex,
providing crystals suitable for X-ray crystallography, but which rapidly lost solvent when removed
from the mother liquor. Yield 31.3 mg (69%). M.p. 252-255C (dec.).
3.3.2.3. [{Cu(NO3)2}2(3)] (15)
Copper nitrate (25 mg, 0.103 mmol) and 3 (20.0 mg, 0.048 mmol) were both dissolved in
methanol and combined. Diffusion of diethyl ether into the reaction mixture gave green crystals,
suitable for X-ray crystallography. Yield 23.5 mg (62%). M.p. 247-250ºC (dec.). Analysis: calc. for
C26H20N10O12Cu2 (791.59) C 39.45, H 2.55, N 17.69; found C 39.83, H 2.16, N 17.84%.
3.3.2.4. [(PdCl2)2(3)].CH3OH.H2O (16)
Palladium chloride (19.0 mg, 0.107 mmol) was dissolved in 2M hydrochloric acid (2 mL) and
added slowly to a hot methanolic solution of 3 (20.1 mg, 0.048 mmol). The solution turned yellow
and a fine yellow solid precipitated. After heating for 30 minutes, the precipitate was collected by
filtration and dried in vacuo. Yield 23.1 mg (59%). M.p. >301ºC (dec.). Analysis: calc. for
C26H20N6Cl4Pd2.CH3OH.H2O (821.19) C 39.49, H 3.19, N 10.23; found C 39.61, H 2.62, N 9.58%.
The complex was insoluble in common NMR solvents.
3.3.3. Complexes of 4
3.3.3.1. [Ag2(4)](PF6)2 (17a) and [{Ag(CH3CN)}2(4)2](PF6)2.4CH3CN (17b)
Ligand 4 (20.0 mg, 0.043 mmol) and silver hexafluorophosphate (24.0 mg, 0.095 mmol) were
each dissolved in hot acetonitrile, the solutions combined and left to slowly evaporate. A colourless
crystalline solid, 17a precipitated from the reaction mixture. 17a: Yield 35.5 mg (85%). M.p.
>189ºC. Analysis: calc. for C30H22N6F12P2Ag2 (972.20) C 37.06, H 2.28, N 8.64; found C 38.97, H
2.53, N 8.75%. Plate-like crystals of 17b formed on the side of the reaction vial when the filtrate was
left to evaporate.
3.3.3.2. [{Cu(NO3)2}2(4)] (18)
Copper nitrate (21.8 mg, 0.090 mmol) and 4 (20.2 mg, 0.043 mmol) were both dissolved in hot
methanol, the solutions combined and then cooled. The methanol was allowed to slowly evaporate
giving a green precipitate, which was collected and dried in vacuo. Yield 20 mg (55%). M.p. 269271ºC (dec.). Analysis: calc. for C30H22N10O12Cu2 (841.65) C 42.81, H 2.63, N 16.64; found C
42.57, H 2.53, N 16.46%.
3.3.3.3. [(PdCl2)2(4)] (19)
Palladium chloride (14.9 mg, 0.084 mmol) was dissolved in 2M hydrochloric acid (2 mL) and
added slowly to a hot methanolic solution of 4 (20.2 mg, 0.043 mmol). The solution turned yellow
and a fine yellow solid precipitated. After heating for 30 minutes, the yellow precipitate was
collected by filtration and dried in vacuo. Yield 30 mg (85%). M.p. >315ºC (dec.). Analysis: calc.
for C30H22N6Cl4Pd2 (821.19) C 43.88, H 2.70, N 10.23; found C 43.75, H 2.72, N 10.35%. The
complex was insoluble in common NMR solvents.
3.3.4. Complexes of 5
3.3.4.1. [{Cu(NO3)2}2(5)]1½CH2Cl2 (20)
A solution of copper nitrate (21.9 mg, 0.091 mmol) dissolved in methanol and 5 (20.1 mg, 0.043
mmol) dissolved in dichloromethane were combined and left to stand. Vapour diffusion of diethyl
ether into this solution gave a green crystalline precipitate. Yield 25.7 mg (62%). M.p. 281-283ºC
(dec.). Analysis: calc. for C30H22N10Cu2O12.1½CH2Cl2 (965.95) C 39.04, H 2.60, N 14.45; found C
39.28, H 2.11, N 14.29%.
3.3.4.2. [(PdCl2)2(5)].H2O (21)
Palladium chloride (15.5 mg, 0.087 mmol) was dissolved in 2M hydrochloric acid (2 mL) and
added to a methanol solution of 5 (19.9 mg, 0.043 mmol). Immediately a pale yellow precipitate
formed, which was collected and dried in vacuo. Yield 28.0 mg (78%). M.p. >290ºC (dec.).
Analysis: calc. for C30H22N6Cl4Pd2.H2O (839.20) C 42.94, H 2.88, N 10.01; found C 43.20, H 2.80,
N 10.08%.
3.3.5. Complexes of 6
3.3.5.1. [Ag2(6)](BF4)2.CH3CN.H2O (22.CH3CN.H2O)
Silver tetrafluoroborate (18 mg, 0.092 mmol) and 6 (20 mg, 0.043 mmol) were both dissolved in
acetonitrile and combined. Vapour diffusion of diethyl ether into the acetonitrile reaction mixture
gave colourless crystals, suitable for X-ray crystallography. Yield 24.4 mg (62%). M.p. >180ºC
(dec.). Analysis: calc. for C30H22N6B2F8Ag2.CH3CN.H2O (914.95) C 42.01, H 2.97, N 10.72; found
C 41.76, H 3.22, N 10.89%.
3.3.5.2. [Ag2(6)](PF6)2 (23)
Silver hexafluorophosphate (24 mg, 0.095 mmol) and 6 (20 mg, 0.043 mmol) were both
dissolved in acetonitrile and the solutions combined. Vapour diffusion of pentane into the reaction
mixture gave colourless crystals suitable for X-ray crystallography, but which were unstable when
removed from their mother liquor. Yield 4.0 mg (9%).
3.3.5.3. [{Cu(NO3)2(CH3OH)}2(6)] (24)
Copper nitrate (22 mg, 0.091 mmol) and 6 (20 mg, 0.043 mmol) were both dissolved in
methanol, the solutions combined and left to stand. Vapour diffusion of diethyl ether into this
solution gave a green crystalline precipitate. Yield 20.2 mg (52%). M.p. 266-267ºC (dec.). Analysis:
calc. for C32H30N10Cu2O14 (905.73) C 42.43, H 3.34, N 15.46; found C 42.27, H 3.11, N 15.77%.
3.3.5.4. [(PdCl2)2(6)].H2O (25)
Palladium chloride (16.2 mg, 0.090 mmol) was dissolved in 2M hydrochloric acid (2 mL) and
added to a methanol solution of 6 (20 mg, 0.043 mmol). Immediately a pale yellow precipitate
formed, which was collected and dried in vacuo. Yield 33.0 mg (91%). M.p. >290ºC (dec.).
Analysis: calc. for C30H22N6Cl4Pd2.H2O (839.20) C 42.94, H 2.88, N 10.01; found C 43.06, H 2.67,
N 9.82%. 1H NMR (DMSO-d6)  8.90 (d, J = 4.8 Hz, 4H, H6’), 8.44 (t, J = 7.4 Hz, 4H, H4’), 8.16 (t,
J = 7.4 Hz, 4H, H5’), 7.90 (d, J = 8.3 Hz, 2H, H4/5), 7.57 (m, 8H, H1/8, H3/6, H3’).
3.4. X-Ray crystallography
The crystal data, data collection and refinement parameters are given in Table 2. Measurements
were made at 168(2) K with a Siemens CCD area detector using graphite monochromatised Mo K
( = 0.71073 Å) radiation. The intensities were corrected for Lorentz and polarisation effects and for
absorption [32]. The structures were solved by direct methods using SHELXS-97 [33], and refined
on F2 using all data by full-matrix least-squares procedures using SHELXL-97 [34]. All nonhydrogen atoms were refined with anisotropic displacement parameters. Hydrogen atoms were
included in calculated positions with isotopic displacement parameters 1.2 times the isotropic
equivalent of their carrier carbon atoms. Diagrams were generated using the program X-Seed [35] as
an interface to POV-Ray. Additional refinement details for individual structures are described below.
Structure 10: In this structure three of the fluorine atoms in part 2 of the disordered
tetrafluoroborate anion were modelled isotropically.
Structure 12: Crystals of compound 12 were of poor quality and relatively weakly diffracting
with very few reflections observed at high angles. The structure was refined using only data to a
theta angle of 22.5.
Structure 13: The data collected for compound 13 was not of a high quality as evidenced by the
relatively high Rint of 0.1233. The structure was refined using only data to a theta angle of 24.0. The
final refinement still contained a considerable number of diffuse electron density peaks that could
not be adequately modelled as solvent. The carbon and oxygen atoms of a methanol solvate
molecule were refined with ISOR restraints and the hydrogens on the two water solvate molecules in
the asymmetric unit were not located in the difference map.
Structure 14: The structure reported for compound 14 was solved in the monoclinic space group
Cc. ADDSYM detects a centre of symmetry in the Cc solution (82% fit) and 14 can be solved in the
higher symmetry space group C2/c, but the resulting refinement was highly unsatisfactory. In
addition to non-planar benzene and pyridine rings in the C2/c solution, there are large numbers of
non-positive definite atoms and large esds on the bond lengths and angles. In the reported Cc
solution the diethyl ether solvate molecule is refined isotropically. There are also large anisotriopic
displacement parameters for the fluorine atoms of some of the hexafluorophosphate anions
consistent with significant thermal vibrations or partial disorder.
Structure 22: In structure 22 part 2 of the disordered acetonitrile molecule (C72’ and C73’) was
modelled isotropically. One of the half occupied tetrafluoroborate anions (B2, F5, F6, F7) is
disordered over a special position (0, 1, ½). The boron atom (B3) of the other half occupied
tetrafluoroborate anion was modelled isotropically.
4. Conclusions
In summary, four new nitrogen-containing heterocyclic ligands were prepared incorporating di2-pyridylamine subunits, and the coordination chemistry of these, and a previously reported ligand,
was investigated with silver(I), copper(II) and palladium(II) precursors. A palladium-catalysed
synthetic methodology, which provided for in situ synthesis of the di-2-pyridylamine subunits, was
effectively used to provide a new route to this type of di-2-pyridylamine-based ligand. A crystal
structure of one of these ligands (5) demonstrated that the di-2-pyridylamine subunits are orthogonal
to the planar central core of such ligands, and that this conformation is observed in copper(II)
complexes of these ligands. In a series of 1-D coordination polymers obtained with silver(I)
precursors the ligands were found to bridge either two silvers (in a hypodentate mode) or four silvers
(in a more divergent mode) in preference to a chelating mode of coordination. This generated a
twelve-membered dimetallocycle connecting unit as a common motif within these 1-D coordination
polymers. Weaker secondary interactions, such as Ag···-bonding, were found to play a role in
determining the overall shape of the resulting structures.
5. Supplementary data
CCDC 272066 - 272074 contain the supplementary crystallographic data for this paper. These
data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK;
fax:
(internat.) +44-1223/336-033; E-mail: deposit@ccdc.cam.ac.uk].
Acknowlegements
We thank the Royal Society of New Zealand for generous financial support from the Marsden
fund and a James Cook Research Fellowship (P.J.S.).
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(b) I. Ino, L. P. Wu, M. Munakata, T. Kuroda-Sowa, M. Maekawa, Y. Suenaga, R. Sakai,
Inorg. Chem. 39 (2000) 5430-5436;
(c) M. Munakata, L. P. Wu, T. Kuroda-Sowa, M. Maekawa, Y. Suenaga, T. Ohta, H. Konaka,
Inorg. Chem. 42 (2003) 2553-2558.
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D. Gillard, J. A. McCleverty), Pergamon Press, Oxford, 1987, 775-859;
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Covey, C. L. Prentice, Chem. Mater. 8 (1996) 2030-2040.
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Trans. (1984) 1349-1356.
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Graphical Abstract
N
N
N
N
N
N
Eighteen metal complexes of five bridging ligands, each containing two di-2-pyridylamine
substituents attached to a central benzene or naphthalene core, have been synthesised. X-ray crystal
structures of one ligand, six silver(I) complexes and two copper(II) complexes are described.
H
N
N
X
X
N
N
N
n
n
(a)
(b)
N
1
(c)
Fig. 1. A schematic diagram of (a) the type of arene based heterocyclic ligands previously reported
by us, (b) the type under investigation in this work and (c) di-2-pyridylamine (1).
Fig. 2. A perspective view of 5, illustrating the out-of-plane conformation of the di-2-pyridylamine
subunits.
Fig. 3. A perspective view of the asymmetric unit of complex 9, with the silver cation and the nitrate
anion shown as spheres, and rods used to represent the two half-ligand molecules. Selected bond
lengths (Å) and angles (): Ag1-N41 2.261(3), Ag1-N11 2.263(2), Ag1-O1 2.418(2), N41-Ag1-N11
147.79(8), N41-Ag1-O1 111.55(9), N11-Ag1-O1 100.37(9).
Fig. 4. A partial packing diagram of the 1-D zig-zag coordination polymer 9, with the nitrate anions
orientated on alternating sides of the axis of the coordination polymer. The silver cations and the
nitrate anions are shown as spheres, and rods are used to represent the ligand molecules. Weak
1/2-Ag···-interactions are indicated by thin dashed lines with Ag-C distances in the range 2.965 –
3.057 Å.
Fig. 5. A perspective view of the asymmetric unit of 10 with the disordered component of the
tetrafluoroborate anion omitted for clarity. The silver cations and the fluorine atoms of the
tetrafluoroborate anion are represented as spheres. Selected bond lengths (Å) and angles (): Ag1N11 2.163(2), Ag2-N30 2.399(3), Ag2-N21 2.429(2), N11-Ag1-N11A 179.98(10), N30A-Ag2-N30
91.84(13), N30-Ag2-N21 89.75(8), N30-Ag2-N21A 160.18(8), N21-Ag2-N21A 95.41(10).
Fig. 6. A perspective view of the extended structure of the 1-D zig-zag coordination polymer 10. The
silver cations are shown as spheres, and rods are used to represent the ligand and coordinated solvent
molecules. Weak 1-Ag···-interactions are indicated by thin dashed lines with Ag-C distances of
2.831 and 2.975 Å.
Fig. 7. A perspective view of the asymmetric unit of 14, with the silver centres and non-coordinated
solvate molecules represented as spheres and with the ligands and coordinated acetonitrile molecules
in stick representation. Hydrogen atoms and non-coordinated hexafluorophosphate anions are not
shown for clarity. Selected bond lengths (Å) and angles (): Ag1-N41A 2.229(5), Ag1-N51'
2.233(5), Ag1-N60 2.311(7), Ag2-N41'B 2.213(5), Ag2-N51 2.247(5), Ag2-N90 2.342(7), Ag3-N80
2.203(7), Ag3-N21 2.259(6), Ag3-N31' 2.516(6), Ag3-N85 2.580(8), Ag4-N75 2.225(6), Ag4-N21'
2.258(5), Ag4-N31 2.476(6), Ag4-N70 2.615(8), N41A-Ag1-N51' 147.27(18), N41A-Ag1-N60
108.3(2), N51'-Ag1-N60 103.6(2), N41'B-Ag2-N51 147.49(19), N41'B-Ag2-N90 113.3(2), N51Ag2-N90 97.9(2), N80-Ag3-N21 168.5(2), N80-Ag3-N31' 98.4(2), N21-Ag3-N31' 93.09(19), N80Ag3-N85 94.2(3), N21-Ag3-N85 85.7(2), N31'-Ag3-N85 92.2(3), N75-Ag4-N21' 168.3(2), N75Ag4-N31 96.1(2), N21'-Ag4-N31 95.15(18), N75-Ag4-N70 96.6(2), N21'-Ag4-N70 86.6(2), N31Ag4-N70 89.9(2).
(a)
(b)
=
N
N
N
N
N
N
Fig. 8. Schematic representations showing the connectivity and arrangement of the silver atoms of
the 1-D coordination polymers (a) 10 and (b) 13/14, showing the identical connectivity, but different
architectures, of the structures.
Fig. 9. The asymmetric unit of the AgNO3 structure (13). The silver centres and nitrate anions are
represented by spheres and non-coordinated diethyl ether, acetonitrile, methanol and water solvate
molecules are omitted for clarity.
Fig. 10. A perspective view of complex 17b with non-coordinated solvate molecules and
hexafluorophosphate anions excluded for clarity. The silver centres are shown as spheres. Selected
bond lengths (Å) and angles (): Ag1-N51A 2.240(5), Ag1-N21 2.267(4), Ag1-N62 2.294(5), N51AAg1-N21 143.88(15), N51A-Ag1-N62 115.82(17), N21-Ag1-N62 100.15(18).
Fig. 11. A perspective view of the asymmetric unit of 22.3CH3CN, with non-coordinated
tetrafluoroborate anions omitted for clarity. The silver centres are shown as spheres. Selected bond
lengths (Å) and angles (): Ag1-N31 2.304(6), Ag1-N41A 2.348(7), Ag1-N61 2.424(7), Ag1-N71
2.539(9), Ag2-N21 2.212(6), Ag2-N51A 2.247(7), Ag2-N81 2.337(8), N31-Ag1-N41A 139.1(2),
N31-Ag1-N61 126.4(2), N41A-Ag1-N61 93.3(2), N31-Ag1-N71 95.9(4), N41A-Ag1-N71 98.0(4),
N61-Ag1-N71 83.6(3), N21-Ag2-N51A 150.2(2), N21-Ag2-N81 103.2(2), N51A-Ag2-N81
105.1(3).
=
N
N
N
N
Fig. 12. A schematic representation of compound 22, showing the connectivity within the 1-D
coordination polymer.
Fig. 13. A perspective view of the copper nitrate structure 12.2(CH3)2SO, with the copper centres
and nitrate anions represented by spheres and coordinated DMSO and ligand 2 shown in stick
representations. Selected bond lengths (Å) and angles (): Cu1-O60 1.949(6), Cu1-N21 1.963(6),
Cu1-N31 2.021(7), Cu1-O41 2.028(6), Cu1-O51 2.235(6), O60-Cu1-N21 174.2(3), O60-Cu1-N31
88.5(2), N21-Cu1-N31, 87.0(2), O60-Cu1-O41 92.4(2), N21-Cu1-O41 90.7(2), N31-Cu1-O41
161.9(2), O60-Cu1-O51 91.5(2), N21-Cu1-O51 93.8(2), N31-Cu1-O51 117.0(2), O41-Cu1-O51
81.0(2).
Fig. 14. A perspective view of the complex 15.2CH3OH, with the copper centres and nitrate anions
represented by spheres and coordinated MeOH and ligand 3 shown in stick representations. Selected
bond lengths (Å) and angles (): Cu1-O41 1.980(2), Cu1-N21 1.981(2), Cu1-N31 1.982(2), Cu1O51 2.004(2), Cu1-O60 2.265(2), O41-Cu1-N21 173.10(8), O41-Cu1-N31 93.45(9), N21-Cu1-N31
87.36(9), O41-Cu1-O51 92.47(8), N21-Cu1-O51 88.87(8), N31-Cu1-O51 161.44(7), O41-Cu1-O60
84.74(8), N21-Cu1-O60 88.36(8), N31-Cu1-O60 97.75(8), O51-Cu1-O60 100.30(7).
N
N
Br
N
N
N
(a)
(b)
Br
N
Br
N
8
7
H2N
N
NH2
N
4
N
(c)
N
N
N
N
N
3
N
N
NH2
N
(c)
H2N
N
N
N
5 1,5-isomer
6 2,7-isomer
(a) di-2-pyridylamine, CuSO4, KOH, 31%; (b) di-2-pyridylamine,
CuSO4, KOH, 33%; (c) 2-bromopyridine, tBuOK, Pd2(dba)3, BINAP,
toluene; 3, 48%; 5, 54%; 6, 50%.
Scheme 1.
AgNO 3
py
py
N
N
py
AgBF 4
PdCl2
py
Cu(NO3)2
2
py
py
N
N
AgPF6
py
{[Ag2(2)(CH3CN)2](BF4)2}n
(10)
[(PdCl2)2(2)]
(11)
Cu(NO3)2
(12.CH3OH)
[(AgNO3)2(3)]n
(13)
{[Ag2(3)](PF6)2}n
(14)
[{Cu(NO3)2}2(3)]
(15)
[(PdCl2)2(3)].CH3OH.H2O
(16)
[Ag2(4)](PF6)2 +
(17a)
PdCl2
3
AgPF6
[{Ag(CH3CN)}2(4)2](PF6)2.4CH3CN (17b)
py
py
N
(9)
[(Cu(NO3)2)2(2)].CH3OH
AgNO 3
py
[AgNO3(2)]n
N
py
py
Cu(NO 3)2
[{Cu(NO3)2}2(4)]
(18)
[(PdCl2)2(4)]
(19)
[{Cu(NO3)2}2(5)]1½CH2Cl2
(20)
[(PdCl2)2(5)].H2O
(21)
PdCl2
4
py
Cu(NO3)2
N
py
py
N
py
PdCl2
5
py
N py
AgBF 4
AgPF6
Cu(NO3)2
[Ag2(6)](BF4)2.CH3CN.H2O
(22.CH3CN
.H2O)
[Ag2(6)](PF6)2
(23)
[{Cu(NO3)2(CH3OH)}2(6)]
(24)
[(PdCl2)2(6)].H2O
(25)
PdCl2
N py
py
6
Scheme 2.
Table 1.
The 1H NMR signals and CIS values for 25 in d6-DMSO.
H1/H8
H3/H6
H4/H5
H3’
H4’
H5’
H6’
6
7.63
7.31
8.01
7.12
7.77
7.12
8.32
25
7.57
7.57
7.90
7.57
8.44
8.16
8.90
CIS
-0.06
+0.26
-0.11
+0.45
+0.67
+1.04
+0.58
Table 2.
Crystal data and X-ray experimental details.
Compound
5
9
10
13
14
Empirical formula
C30H22N6
C26H20AgN7O3
C30H26Ag2B2F8N8
C61H64Ag4N18O16
C72H74Ag4F24N20OP4
Formula weight
466.54
586.36
887.95
1736.78
2246.87
Crystal system
Monoclinic
Triclinic
Monoclinic
Monoclinic
Monoclinic
Space group
P21/n
P-1
C2/c
P21/n
Cc
Unit cell dimensions: a (Å)
6.818(2)
9.788(3)
20.917(7)
11.737(5)
17.656(2)
b (Å)
10.826(4)
10.901(3)
13.665(5)
26.844(10)
21.334(3)
c (Å)
15.586(6)
12.844(3)
12.791(4)
23.194(9)
23.747(3)
 ()
90
69.774(3)
90
90
90
 ()
91.271(13)
68.357(3)
114.064(4)
101.931(6)
94.719(2)
 ()
90
79.025(3)
90
90
90
Volume (Å )
1150.1(8)
1192.2(5)
3338.4(19)
7150(5)
8914.9(18)
Z
2
2
4
4
4
Density (calculated) (Mg/m3)
1.347
1.633
1.767
1.613
1.674
-1
Absorption coefficient (mm )
0.083
0.890
1.254
1.156
1.042
F(000)
488
592
1752
3488
4472
Crystal size (mm )
0.60 x 0.39 x 0.28
0.60 x 0.15 x 0.13
0.48 x 0.37 x 0.05
0.54 x 0.18 x 0.16
0.73 x 0.55 x 0.31
Theta range for data collection ()
2.29 to 25.00
2.24 to 26.40
2.13 to 26.46
1.76 to 24.00
2.09 to 26.47
Reflections collected
10422
14630
20972
73825
39624
Independent reflections [R(int)]
1968 [0.0328]
4743 [0.0436]
3376 [0.0343]
11079 [0.1233]
13417 [0.0305]
Observed reflections [I>2(I)]
1685
3967
2366
8435
12551
Data / restraints / parameters
1968 / 0 / 163
4743 / 0 / 334
3376 / 0 / 250
11079 / 15 / 910
13417 / 5 / 1111
Goodness-of-fit on F
1.144
1.020
0.994
1.243
1.068
R1 [I>2(I)]
0.0468
0.0370
0.0248
0.1113
0.0395
wR2 (all data)
0.1081
0.1005
0.0495
0.2169
0.1028
3
3
2
Table 2 (Cont).
Compound
17b
22.3CH3CN
12.2(CH3)2SO
15.2CH3OH
Empirical formula
C72H62Ag2F12N18P2
C36H31Ag2B2F8N9
C30H32Cu2N10O14S2
C28H28Cu2N10O14
Formula weight
1685.08
979.06
947.86
855.68
Crystal system
Monoclinic
Monoclinic
Triclinic
Monoclinic
Space group
P21/c
P21/c
P-1
C2/c
Unit cell dimensions: a (Å)
18.564(10)
13.765(4)
9.191(5)
22.430(9)
b (Å)
14.131(9)
25.188(7)
9.841(5)
9.719(4)
c (Å)
14.550(8)
13.215(4)
11.092(6)
16.300(6)
 ()
90
90
84.950(7)
90
 ()
107.33(2)
113.796(4)
68.561(9)
100.987(5)
 ()
90
90
86.950(7)
90
Volume (Å )
3644(4)
4192(2)
929.9(8)
3488(2)
Z
2
4
1
4
Density (calculated) (Mg/m )
1.536
1.551
1.693
1.629
Absorption coefficient (mm-1)
0.668
1.007
1.338
1.302
F(000)
1704
1944
484
1744
Crystal size (mm )
0.60 x 0.40 x 0.08
0.50 x 0.33 x 0.31
0.35 x 0.11 x 0.10
0.35 x 0.30 x 0.10
Theta range for data collection ()
2.13 to 25.00
1.81 to 25.00
2.38 to 22.49
2.29 to 26.37
Reflections collected
14568
27661
4182
21280
Independent reflections [R(int)]
6383 [0.0450]
7278 [0.0396]
2293 [0.0388]
3521 [0.0451]
Observed reflections [I>2(I)]
4015
4977
1755
2612
Data / restraints / parameters
6383 / 0 / 481
7278 / 1 / 556
2293 / 0 / 262
3521 / 0 / 249
Goodness-of-fit on F2
1.017
1.102
1.058
1.001
R1 [I>2(I)]
0.0505
0.0666
0.0714
0.0330
wR2 (all data)
0.1420
0.1868
0.1901
0.0856
3
3
3