Synthesis, Structures, and Characterization of Dimeric Neutral Dithiolato-Bridged Tungsten Complexes

The quadruply bridged bimetallic dithiolato complex [(Cp*W)(2)(mu-S)(2)(mu,(2)-S2CH2)] (3) and the open-cage triple-decker complex [(Cp*W)(2)(mu-S)(mu-(4):(4)-B2H2S2)] (2) have been prepared by treatment of CS2 with in situ generated [(Cp*W)(2)(B2H6)(2)] (1) obtained by the reaction of [Cp*WCl4] with [LiBH4<bold>thf</bold>]. The solid-state X-ray diffraction structures of these complexes show the presence of doubly bridging (2)-S2B2H2 and (2)-S2CH2 ligands with a short W-W bond. While many dimolybdenum-sulfur compounds are known, examples of the tungsten-dithilato complexes are relatively few, and in this respect, the isolation of [(Cp*W)(2)(mu-S)(2)(mu,(2)-S2CH2)] represents a rare example of this type. Electronic-structure analysis, on the grounds of density functional theory (DFT), together with X-ray diffraction studies, has rationalized the presence of short W-W and B-B bonds. Large HOMO-LUMO gaps have been observed for both compounds, which is consistent with their thermodynamic stability. All of the compounds have been characterized by mass spectrometry, IR spectroscopy, and H-1 NMR, B-11 NMR, and C-13 NMR spectroscopy in solution, and the structural architectures have been unambiguously established by X-ray diffraction crystallographic analysis.