1
Microwave Spectra and Structures of
H4C2CuCl and H4C2AgCl
by
Nicholas R. Walker, Susanna L. Stephens,
Victor A. Mikhailov and Anthony C. Legon
Rod
rotator
Laser
arm
Gas line
attached
to solenoid
valve
Microwave emission
antenna
Objectives
• Apply microwave spectroscopy to study interactions of the broadest
significance in inorganic chemistry. Examples include complexes
formed between CO, H2S, N2, H2O, NH3 and the noble metal atoms
Cu and Ag.
• Establish laser ablation as a general method for the production of
metal-ligand complexes for study by microwave spectroscopy.
• Compare units such as H4C2CuCl, H4C2AgCl with hydrogenbonded analogues, e.g. H4C2HCl, to identify common trends.
• Previous works include studies of OCMX by Gerry and co-workers.
Also N2MX and H2SMX by Walker, Legon and co-workers.
Balle-Flygare FTMW spectrometer
Laser arm
Rod rotater
532 nm Nd:YAG laser
Focusing lens
Solenoid valve
Adiabatic expansion of CCl4 / C2H4 / Ar
Gas line
Copper or silver
rod and rod rotater
Connections to
microwave emission
and detection circuits
Fixed
mirror
To
vacuum
Adjustable
mirror
H4C2CuCl and H4C2AgCl
X
• Asymmetric tops of C2v symmetry.
• Dipole moment on a axis, Expect
a-type transitions.
M
• Determine B0, C0, and possibly
A0?
• Sensitive to rMCl, rMX and maybe
rCC.
H4C2AgCl
H4C2109Ag35Cl
9 11

2
2
JK-1 K+1 JK-1 K+1 = 313  414
H4C2107Ag35Cl
F′-F′′ = 7  9
2
2
Silver rod, natural
isotope abundances.
3000 averaging cycles
Isotopically-enriched 107Ag
rod. 3000 averaging cycles
12404.55
12404.75
Frequency / MHz
12404.95
H4C263Cu35Cl
JK-1 K+1 JK-1 K+1 = 202  303
F′′-F′ = 7  9 , 23
2
2
5
7
 , 45
2
2
7
9
 , 56
2
2
1000 averaging cycles
11612.5
11612.7
11612.9
Frequency / MHz
11613.1
11613.3
H4C2AgCl
2H4
12C
109Ag35Cl
12C
2H4
107Ag37Cl
12C
109Ag37Cl
2H4
12C
A0/ MHz
B0/MHz
C0/MHz
ΔJ/kHz
ΔJK/kHz
χaa(Cl)/MHz
{ χbb(Cl)
χcc(Cl)}/MHz
N
σr.m.s /kHz
Pb / u Å2
Pc / u Å2
24301(47)a,b
1602.15391(34)
1533.53207(34)
0.2198(84)
13.59(41)
27.856(25)
24427(33)
1602.04542(24)
1533.43255(24)
0.2295(64)
12.33(29)
27.850(18)
24236(57)
1556.60563(31)
1491.74602(31)
0.191(11)
13.75(48)
22.026(28)
24329(62)
1556.44731(39)
1491.59972(39)
0.202(11)
12.84(39)
21.962(29)
2.75(10)
2.719(91)
1.91(12)
2.02(15)
31
2.7
17.46(2)
3.34(2)
28
1.8
17.40(2)
3.29(2)
25
2.3
17.48(2)
3.37(2)
26
3.0
17.44(2)
3.33(2)
a
107Ag35Cl
2H4
Spectroscopic
constant
Numbers in parentheses are one standard deviation in units of the last significant figure.
b The C rotational constant of 12C H is 24824.20 MHz.
0
2 4
6 isotopologues
X
Distances and
angles
r(XAg)/Ǻ
r(Ag–Cl)/Ǻ
r(C–C)/Ǻ
r(C–H)/Ǻ
Angle(CCH)
/deg.
Dihedral
angle(AgCCH)
/deg.
rs-geometry
r0-geometry
2.1697(4)a
2.2701(2)
1.354(40)


2.1719(9)
2.2724(8)
1.3518(4)
(1.0853)b
123.02(6)

(94.51)c
r0 Geometrya,b of isolated C2H4
rCC= 1.3386(14) Å
rCH= 1.0849(13) Å
CCH=121.16(11)
a) N. C. Craig, P. Gröner and D. C. McKean, J. Phys. Chem. A 110, 7461-7469 (2006).
b) T. C. Tan, K. I. Goh, P. P. Ong and H. H. Tro, J Mol. Spectrosc. 307, 189-192 (2001).
r0 bond length of AgCl= 2.2836 Å;
K. D. Hensel, C. Styger, W. Jäeger, A.J. Merer and
M.C.L. Gerry; J. Chem. Phys. 99, 3320 (1993).
a Small
rs coordinate for silver calculated
b Assumed from ab initio value corrected
using the first moment condition.
for the difference between re and r0 for C2H4.
cAssumed unchanged from ab initio r value.
e
H4C2CuCl
a
2H4
Spectroscopic constant
12C
63Cu35Cl
A0/ MHz
B0 / MHz
C0 / MHz
ΔJ / kHz
ΔJK / kHz
χaa(Cu) / MHz
{ χbb(Cu) χcc(Cu)}/MHz
χaa(Cl) /MHz
{ χbb(Cl) χcc(Cl)} /MHz
(Cbb + Ccc) / kHz
N
σr.m.s / kHz
24076(42)
1988.92787(30)
1882.69407(30)
0.281(26)
18.89(63)
63.8102(76)
44.55(28)
20.9974(95)
5.657(55)
12.38(77)
56
3.5
12C
2H4
65Cu35Cl
24076*
1988.625649(28)
1882.41064(28)
0.281*
18.89*
59.046(30)
41.15*
20.9906(88)
5.659*
13.58(45)
13
1.0
12C
63
37
2H4 Cu Cl
24076*
1933.68868(20)
1833.15068(20
0.281*
18.89*
63.8125(39)
44.54*
16.5534(52)
4.46*
12.38
24
1.3
Numbers in parentheses are one standard deviation in units of the last significant figure.
b The C rotational constant of 12C H is 24824.20 MHz; N. C. Craig, P. Gröner and D. C.
0
2 4
McKean, J. Phys. Chem. A 110, 7461-7469 (2006).
Nuclear Quadrupole Coupling Constants
 aa (M) / MHz
 aa (Cl) / MHz
M=Cu
M=Cu
MCla
ArMCla
KrMCla
H2OMClb
H3NMClb
H2SMClc
OCMClb
H4C2MCl
16.2
33.2
36.5
50.3

61.8
70.8
63.8
32.1
28.0
27.3
25.5

23.0
21.5
21.0
NaCld
ArNaCld

M=Ag
36.4
34.5
33.8
32.3
29.8
29.4
28.1
27.9
/ MHz
5.7
5.8
Ionicity, ic
M=Cu
M=Ag
0.71
0.67
0.74
0.69
0.75
0.69
0.77
0.71

0.73
0.79
0.73
0.80
0.74
0.81
0.75
Ionicity, ic
0.95
0.95
• Intense signals.
• Nuclear quadrupole coupling constants and force constants
(calculated from (B0+C0)/2 and DJ) indicate strong interactions
between the metal and C2H4.
Theory
rAgCl / Å
cc-pVTZa
cc-pVQZb
r0
2.280
2.272
2.273(6)
cc-pVTZ
cc-pVQZ
r0
rAgCl / Å
2.2783
2.2714
2.26333(6)
cc-pVTZ
cc-pVQZ
r0
rAgCl / Å
2.2835
2.2777
2.26882(13)
cc-pVTZ
cc-pVQZ
r0
rAgCl / Å
2.2837
2.2771
2.2724(8)
H2OAgCl
rAgO / Å
2.280
2.209
2.198(10)
H3NAgCl
rAgN / Å
2.1619
2.1530
2.15444(6)
H2SAgCl
rAgS / Å
2.4049
2.3875
2.38384(12)
H4C2AgCl
rAgX / Å
2.1975
2.1945
2.1719(9)
/˚
45.0
43.7
37.4(16)
AgNH
111.87
111.68
113.48(2)
/˚
76.2
76.2
78.052(6)
CCH
121.46
121.46
123.02(6)
Dr. David Tew, University
of Bristol
• CCSD(T) calculations.
• cc-pVTZ basis sets for
H, O.
• cc-pV(T+d)Z basis set
for Cl.
• cc-pVTZ-PP for Ag.
Acknowledgments and Advertisements
Susanna L. Stephens
Anthony C. Legon
Colin M. Western – for adapting
and developing PGOPHER for
microwave spectroscopy.
Victor A. Mikhailov
<http://pgopher.chm.bris.ac.uk/>
Theory
David P. Tew
Jeremy N. Harvey
MH02, now follows – CP-FTMW Spectroscopy of CF3ICO, Susanna Stephens.
WH04, (Wed. 2:21) – Microwave Spectrum and Structure of H2O AgF, Susanna Stephens.
WH05, (Wed. 2.38) – Internal Rotation in CF3INH3 and CF3IN(CH3)3 Probed by CP-FTMW
Spectroscopy , Nick Walker.
Financial Support
Engineering and Physical
Sciences Research
Council