文摘
Reaction of TpiPrMoVIOS(OAr) with cobaltocene in toluene results in the precipitation of brown, microcrystalline oxosulfido-Mo(V) compounds, [CoCpb>2b>][TpiPrMoVOS(OAr)] (Cp鈥?/sup> = 畏5-Cb>5b>Hb>5b>鈥?/sup>, TpiPr鈥?/sup> = hydrotris(3-isopropylpyrazol-1-yl)borate, OAr鈥?/sup> = phenolate or 2-sBu, 2-tBu, 3-tBu, 4-sBu, 4-Ph, 3,5-sBub>2b>, 2-COb>2b>Me, 2-COb>2b>Et or 2-COb>2b>Ph derivative thereof). The compounds are air- and water-sensitive and display 谓(Mo鈺怬) and 谓(MoS) IR absorption bands at ca. 890 and 435 cm鈥?, respectively, 20鈥?0 cm鈥? lower in energy than the corresponding bands in TpiPrMoOS(OAr). They are electrochemically active and exhibit three reversible cyclovoltammetric waves (E(MoVI/MoV) = 鈭?.40 to 鈭?.66 V, E([CoCpb>2b>]+/CoCpb>2b>) = 鈭?.94 V and E(CoCpb>2b>/[CoCpb>2b>]鈭?/sup>) = 鈭?.88 V vs SCE). Structural characterization of [CoCpb>2b>][TpiPrMoOS(OCb>6b>Hb>4b>COb>2b>Et-2)]路2CHb>2b>Clb>2b> revealed a distorted octahedral Mo(V) anion with Mo鈺怬 and MoS distances of 1.761(5) and 2.215(2) 脜, respectively, longer than corresponding distances in related TpiPrMoOS(OAr) compounds. The observation of strong S(1s) 鈫?(S(3p) + Mo(4d)) S K-preedge transitions indicative of a d1 sulfido-Mo(V) moiety and the presence of short Mo鈺怬 (ca. 1.72 脜) and MoS (ca. 2.25 脜) backscattering contributions in the Mo K-edge EXAFS further support the oxosulfido-Mo(V) formulation. The compounds are EPR-active, exhibiting highly anisotropic (螖g 0.124鈥?.150), rhombic, frozen-glass spectra with gb>1b> close to the value observed for the free electron (gb>eb> = 2.0023). Spectroscopic studies are consistent with the presence of a highly covalent MoS 蟺* singly occupied molecular orbital. The compounds are highly reactive, with reactions localized at the terminal sulfido ligand. For example, the compounds react with cyanide and PPhb>3b> to produce thiocyanate and SPPhb>3b>, respectively, and various (depending on solvent) oxo-Mo(V) species. Reactions with copper reagents also generally lead to desulfurization and the formation of oxo-Mo(V) or -Mo(IV) complexes.