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THROUGH SPACE INTERACTION MEDIATED BY A SULFOXIDE
G. Joel Meyer, Elliott R. Smith, Takahiro Sakamoto, Dennis L. Lichtenberger,* Richard S.
Glass*
Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721,
U.S.A
Email: rglass@u.arizona.edu
Supplemental Materials
General experimental comments.
Electrochemical Measurements
All electrochemical experiments were carried out with a Gamry Reference 3000
potentiostat. All potentials are reported vs. the ferrocenium/ferrocene (Fc+/Fc) couple measured
in CH2Cl2. Voltammetric experiments were conducted at 298 K, by using approximately 1.0 mM
of compound in CH2Cl2 containing 0.20 M Bu4NB(C6F5)4 on a Glassy Carbon working Electrode
(GCE), Ag/AgNO3 reference electrode, and Pt wire counter electrode, under an Ar atmosphere.
CV scans were obtained at 100 mV/s. DPV were obtained with a modulation amplitude varying
between 5, 10 and 50 mV. The area of the GCE was determined to be 0.071 cm 2 from cyclic
voltammetric studies of the oxidation of ferrocene in CH3CN by using 2.5×10–5 cm2/s as its
diffusion coefficient.
Photoelectron Spectroscopy
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Photoelectron spectra were recorded using an instrument that features a 360 mm radius
hemispherical analyzer (McPherson), with a custom-designed photon source, sample cells,
detection, and control electronics.11 Calibration and data analysis were described previously.12
All samples sublimed cleanly, with no visible changes in the spectra during data collection after
initial observation of ionizations from the diiron compounds. The sublimation temperature (at
10–6 Torr) was 192 - 261 oC .
11
. K. Siegbahn, C. Nordling, A. Fahlman and R. Nordberg. In ESCA: Atomic, Molecular and
Solid State Structure Studied by Means of Electron Spectroscopy; Uppsala, Almqvist &
Wiksells: 1967
12
. M.A. Cranswick, A. Dawson, J. Cooney Jon A., N.E. Gruhn, D.L. Lichtenberger, J.H.
Enemark, Inorg. Chem. 2007, 46, 10639.
Synthesis of 6a
2-Bromo-6-ferrocenyl thioanisole. To a solution of 2,6-dibromo(methylthio)benzene
(100 mg, 0.35 mmol) in distilled 1,4-dioxane (0.25 mL) under argon, were added a 2M aqueous
solution of Na2CO3 (0.5 mL), ferroceneboronic acid (190 mg, 0.75 mmol), and Pd(PPh3)4 (30
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mg, 0.03 mmol). The reaction was stirred for 48 h. Water (15 mL) was added to the resulting
suspension and extracted with dichloromethane (30 mL). The organic layer was washed
successively with 1M NaOH (30 mL), brine (30 mL), and H2O (30 mL), dried with anhyd
MgSO4, filtered and evaporated under reduced pressure. The crude product was purified by flash
silica gel chromatography using 20% CH2Cl2 in hexanes as eluent to give 2-bromo-6-ferrocenyl
thioanisole as a red-orange solid (71% yield, Rf = 0.3): 1H NMR(500 MHz, CDCl3) δ 2.22 (3 H,
s), 4.12 (10 H, s), 4.32 (4H, J = 1.9 Hz, t), 4.70 (4H, J = 1.9 Hz, t), 7.11 (1H, J = 7.7 Hz, t), 7.51
(1H, J = 7.7 Hz, dd) , 7.80 (1H, J = 7.7 Hz, dd); 13C NMR δ 19.36, 67.95, 68.13, 69.79, 71.07,
128.45, 137.18, 131.23, 131.41, 135.97, 145.05; IR 3094, 2919, 2849, 1575, 1542, 1422 cm-1;
HRMS (m/z): Calcd for C17H15SFeBr, 385.9427; Found: 385.9430.
Preparation
of
([1,1'-diferrocenyl-3',1'':4'',1''':3''',1''''-triphenyl]-2',2'''-
diyl)bis(methylsulfane) (6a): In a 5 mL round bottom flask, flushed with argon, was added 2bromo-6-ferrocenylthioanisole (80 mg, 0.2 mmol), 1,4-benzenediboronic acid (17 mg, 0.1
mmol), LiCl (32 mg, 0.8 mmol), and palladium(0) tetrakistriphenylphosphine (15 mg, 0.015
mmol), 2M Na2CO3 (0.4 mL), and 1,4-dioxane (0.3 mL). The flask was fitted with a reflux
condenser and stir bar, heated to reflux, and stirred for 16 hours. The dark brown suspension
was dissolved in ethyl acetate (15 mL), washed with 1M NaOH (10 mL), Water (10 mL), then
brine (10 mL). The organic layer was dried over anhydrous magnesium sulfate, filtered and the
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solvent evaporated. An 8” flash silica column was run with 20% dichloromethane in hexanes
was run to afford the desired product in 47% yield: 1H NMR (CDCl3) δ 1.74 (6 H, s), 4.21 (10
H, s), 4.37 (4 H, J = 1.8 Hz, t), 4.77 (4H, J = 1.9 Hz, t), 7.27 (2H, J = 7.5, 1.6 Hz, dd), 7.34 (2H,
J = 7.6 Hz, t), 7.54 (4 H, s), 7.90 (2H, J = 7.7, 1.7 Hz, dd);
13
C NMR δ 19.25, 67.84, 69.72,
71.26, 88.11, 126.68, 128.95, 128.98, 131.22, 134.52, 140.88, 142.48, 145.84; IR 2973, 2852,
1477, 1461 cm-1; HRMS (m/z): Calcd for C40H34S2Fe2, 690.0804; Found: 690.0796.
0 eq
0.25 eq
0.5 eq
1 eq
2 eq
400
600
800
1000
1200
1400
1600
1800
2000
2200
Wavelength (nm)
Figure S 1. UV-Vis/NIR spectra of the chemical oxidation of 5b → 5b+ → 5b2+ in 0.2 M
Bu4NB(C6F5)4 in dichloromethane using [NO]BF4 as oxidant.
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Figure S 2: Ultra-Violet photoelectron spectra of compound 5b.
0
0.1
0.2
0.3
0.4
0.5
0.6
E/V
Figure S3. Differential pulse voltammetry of 6b in CH2Cl2 with 0.2 M Bu4NB(C6F5)4
supporting electrolyte.
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0.9
0.7
0.5
0.3
0.1
-0.1
-0.3
Potential (V)
Figure S4. Cyclic voltammetry of 6b in CH2Cl2 with 0.2 M Bu4NB(C6F5)4
electrolyte.
supporting
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LUMO, -3.48 eV
HOMO, -5.89 eV
HOMO-1, -5.94 eV
HOMO-2, -5.96 eV
HOMO-3, -5.98 eV
HOMO-4, -6.09 eV
HOMO-5, -6.11 eV
HOMO-6, -6.55 eV
HOMO-7, -7.26 eV
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HOMO-8, -7.40 eV
HOMO-9, -7.83 eV
LUMO to HOMO-10 of 5b. Isovalue 0.05
Figure S 5. DFT calculations of 5b.
HOMO-10, -7.85 eV