Article
Inorganic Chemistry, Vol. 48, No. 22, 2009 10583
dinitrogen atmosphere using standard Schlenk techniques.
(Et4N)2[MoIVO(S4)(bdtCl2)], (Et4N)2[MoIVO(S2C2(CO2Me)2)-
(bdt)] (1), and (Et4N)2[MoIVO(S2C2(CO2Me)2)2] (5) were pre-
pared by following established literature procedures.14,28
Synthesis and Characterization of Complexes. (Et4N)(Ph4P)-
[MoVIO2(S2C2(CO2Me)2)(bdt)] (2). An acetonitrile solution of
1 mL containing Me3NO (trimethylamine N-oxide, 4.8 mg, 0.064
mmol) was added to 3 mL of an acetonitrile solution containing 1
(23.2 mg, 0.032 mmol) and Ph4PBr (41.2 mg, 0.098 mmol). The
resultant deep-red solution was concentrated to ∼1 mL. The
addition of 25 mL of ethanol to the solution gave a red-black
microcrystalline powder of 2, which was collected by filtration
and dried in vacuo. Yield: 22.9 mg (73%). Anal. Calcd for
1H NMR (CD3CN, 25 °C, anionic part): δ 3.60 (s, 12H). UV-vis
spectrum (CH3CN): λmax = 358 (ε = 7630), 419 (5370), 536 nm
(1840 M-1 cm-1). ESI-MS (CH3CN): m/z = 542 [M]-, 672
{[M]2- þ Et4Nþ}-, 881 {[M]2- þ Ph4Pþ}-. CV (CH3CN): Epc
(irrev.) = -1.70 V vs SCE. IR (KBr): ν 528 (vs), 692 (s), 724 (s),
763 (m), 838 (s), 869 (s), 997 (m), 1026 (s), 1076 (w), 1109 (vs),
1233 (vs), 1436 (vs), 1484 (s), 1685 (vs), 1708 cm-1 (vs).
Physical Measurements. 1H NMR spectra were recorded with
a JEOL Lambda 300, and the TMS signal was adjusted to 0 ppm.
ESI-MS spectra were measured with a JEOL JMS-700S.
FT-IR spectra were recorded with a Perkin-Elmer Spectrum
One spectrometer. Routine UV-vis spectra were recorded on a
Shimazu-UV 2550 spectrometer. Additional solution electro-
nic absorption spectra were collected using a Hitachi U-3501
UV-Vis-NIR dual-beam spectrometer capable of scanning a
wavelength region between 185 and 3200 nm. Spectral samples
were dissolved in dry, degassed dichloromethane, and the
electronic absorption spectra were measured in a 1-cm path
length, 100 μL, black-masked, quartz cuvette (Starna Cells, Inc.)
equipped with a Teflon stopper. All electronic absorption
spectra were performed at room temperature and repeated at
regular time intervals to ensure the structural stability and
integrity of the complex in solution. Solid-state resonance
Raman (rR) spectra and associated rR excitation profiles were
collected using a system comprised of an PI/Acton SpectraPro
SP-2500i 500 mm focal length imaging spectrograph with a
triple grating turret and a PI/Acton Spec-10:100B back-illumi-
nated 1340 ꢀ 100 pixel digital CCD spectroscopy system with a
cryogenically cooled camera head. A Coherent Innova I302C
Arþ ion laser was the excitation source. Samples were mixed
with either NaCl or a NaCl/Na2SO4 mixture with Na2SO4 as an
internal calibrant.
C44H50MoO6NPS4 3H2O (mol wt 999.09): C, 52.95; H, 5.66;
3
N, 1.40. Found: C, 53.33; H, 5.27; N; 1.62. 1H NMR (CD3CN,
25 °C, anionic part): δ 7.03 (m, 2H), 6.58 (m, 2H), 3.58 (s, 6H).
UV-vis spectrum (CH3CN): λmax = 362 (ε = 8130), 422 (sh,
4970), 530 nm (1880 M-1 cm-1). ESI-MS (CH3CN): m/z = 606
{[M]2- þ Et4Nþ}-, 815 {[M]2- þ Ph4Pþ}-. CV (CH3CN): Epc
(irrev.) = -1.70 V vs SCE. IR (KBr): ν 528 (vs), 691 (s), 723 (s),
759 (m), 836 (s), 870 (s), 997 (m), 1026 (s), 1077 (w), 1108 (vs),
1236 (vs), 1438 (vs), 1484 (s), 1586 (w), 1707 (s), 1716 cm-1 (s).
(Et4N)2[MoIVO(S2C2(CO2Me)2)(bdtCl2)] (3). This complex
was synthesized using the same procedure as 1,14 except
(Et4N)2[MoO(S4)(bdtCl2)] (224 mg, 0.316 mmol) was used
instead of (Et4N)2[MoO(S4)(bdt)]. Yield: 166 mg (67%). Anal.
Calcd for C28H48Cl2MoN2O5S4 (mol wt 787.81): C, 42.69; H,
6.14; N, 3.56. Found: C, 42.83; H, 6.09; N; 3.53. 1H NMR
(CD3CN, anionic part): δ 6.89 (s, 2H), 3.70 (s, 6H). UV-vis
spectrum (CH3CN): λmax = 377 (ε = 3490), 431 (870), 531 nm
(340 M-1 cm-1). ESI-MS (CH3CN): m/z = 264 [M]2-, 658
{[M]2- þ Et4Nþ}-. CV (CH3CN): E1/2(rev.) = -0.11 V vs SCE.
IR (KBr): ν 784 (m), 807 (m), 909 (s), 999 (m), 1017 (m), 1055
(m), 1152 (m), 1172 (m), 1234 (vs), 1325 (m), 1394 (s), 1431 (m),
1454 (m), 1483 (s), 1528 (s), 1696 (s), 1711 cm-1 (s).
Electrochemistry. Cyclic voltammetric measurements were
performed under dinitrogen with a Hokuto Denko HZ-3000
potentiostat.
A set of glassy-carbon working electrodes
(Et4N)(Ph4P)[MoVIO2(S2C2(CO2Me)2)(bdtCl2)] (4). To 10 mL
of an acetonitrile solution of 3 (50.9 mg, 0.065 mmol), 4 mL of an
acetonitrile solution of Me3NO (10.0 mg, 0.133 mmol) was
added. The resultant deep-red solution was stirred for 5 min,
and then Ph4PBr (87.0 mg, 0.207 mmol) was added to the
solution. A brown powder was precipitated by addition of
ethanol to the solution, and this was collected by filtration
and dried in vacuo. Yield: 50.5 mg (75%). Anal. Calcd for
(circular, 3 mm diameter), a SCE reference electrode, and a
platinum counter electrode were employed in these experiments.
X-ray Crystallography. Single crystals of (Et4N)(Ph4P)-
[MoIVO(S2C2(CO2Me)2)(bdt)] (1a) were obtained from an acet-
onitrile solution of 1 in the presence of Ph4PBr. Single crystals of
4 and 6 were obtained by diffusion of diethyl ether into each
acetonitrile solution. Single crystals of (Et4N)2[MoO2(S2C2-
(CO2Me)2)2] (7) were obtained by diffusion of diethyl ether into
an acetonitrile solution containing 5 and Me3NO. Each single
crystal obtained was mounted on a glass fiber, and all X-ray data
were collected at -173 °C on a Rigaku CCD diffractometer with
monochromatic Mo KR radiation. The structures were solved
by direct methods29 and expanded using DIRDIF 99.30 The
non-hydrogen atoms were refined anisotropically by full-ma-
trix least-squares on F2. The hydrogen atoms were attached at
idealized positions on carbon atoms and were not refined. All
structures in the final stages of refinement showed no movement
in the atom positions. The calculations were performed using
Single-Crystal Structure Analysis Software, version 3.8.31 Crys-
tallographic parameters are summarized in Table 1.
C44H48MoNO6PS4 H2O (mol wt. 1030.95): C, 51.26; H, 4.89;
3
N, 1.36. Found: C, 51.13; H, 4.76; N; 1.55. 1H NMR (CD3CN,
25 °C, anionic part): δ 6.73 (s, 2H), 3.59 (s, 6H). UV-vis
spectrum (CH3CN): λmax = 329 (ε = 6670), 358 (5040), 417
(3000), 525 nm (1100 M-1 cm-1). ESI-MS (CH3CN): m/z =
674 {[M]2- þ Et4Nþ}-, 883 {[M]2- þ Ph4Pþ}-. CV (CH3CN):
Epc(irrev.) = -1.66 V vs SCE. IR (KBr): ν 528 (vs), 691 (s), 723
(s), 757 (m), 838 (s), 872 (s), 997 (m), 1027 (s), 1068 (s), 1109 (vs),
1154 (m), 1236 (vs), 1333 (m), 1394 (vs), 1437 (vs), 1483 (vs),
1585 (w), 1680 (s), 1715 cm-1 (s).
(Et4N)(Ph4P)[MoVIO2(S2C2(CO2Me)2)2] (6). An acetonitrile
solution (1 mL) containing Me3NO (6.6 mg, 0.084 mmol) was
added to an acetonitrile solution (5 mL) containing 5 (31.3 mg,
0.040 mmol). An acetonitrile solution (2 mL) of Ph4PBr (50.2 mg,
0.120 mmol) was immediately added to the reaction mixture and
the resultant deep-red solution was concentrated to ca. 1 mL.
When a solution composed of 6 mL of ethanol and 10 mL of
diethyl ether was added to the deep-red solution, a red-black
microcrystalline powder (6) precipitated from the solution. This
was collected by filtration and dried in vacuo. Yield: 28.2 mg
(70%). Anal. Calcd for C44H52MoNO10PS4 (mol wt. 1010.75):
C, 52.32; H, 5.19; N, 1.39. Found: C, 52.35; H, 4.99; N; 1.52.
Electronic Structure Calculations. Spin-restricted gas phase
geometry optimizations and vibrational frequency calculations
for compounds 2, 4, and 6 were performed at the density
functional level of theory using the Gaussian 03W software
package.32 All calculations employed the B3LYP hybrid func-
tional. A LANL2DZ basis set with an effective core potential
was used for Mo and a 6-31G* basis set was used for all light
atoms. Input files were prepared using the molecule builder
function in the Gaussview software package. Frontier molecular
orbitals were generated for the optimized ground states of 2, 4,
and 6, and the contributions of each MO were further analyzed
using the program AOMix.33 Time-dependent DFT calcula-
tions were performed on the optimized ground state geometries,
and the first 40 excited states were calculated. Electron density
(28) Coucouvanis, D.; Hadjikyriacou, A.; Toupadakis, A.; Koo, S. M.;
Ileperuma, O.; Draganjac, M.; Salifoglou, A. Inorg. Chem. 1991, 30, 754–
767.