Abstract
(X)R2S=C=SR2(X) can be regarded as the isoelectronic carbon analogue of [(X)R2S=N=SR2(X)]+ cations, but very little has been reported to date on this compound. In view of its chemical properties and structural features, investigation of this compound has posed an interesting challenge. We report here the first synthesis, isolation, and crystal structure determination of (MeN)Ph2S=C=SPh2(NMe) 6 The desired compound 6 was prepared in essentially quantitative yield by passing a methanolic solution of [(MeN)Ph2S=CH-SPh2(NMe)][ClO4] 5 through a column of the basic resin. The molecular structures 5 and 6 were determined by X-ray crystallographic analysis. The bond lengths of two bridging S-C1, two terminal S-N, and four S-C in 6 are not significantly different from one another. The bridging S-C1 bond lengths of 6 (1.635(4) and 1.636(2) Å) are shorter than those of 5 (1.695(2) and 1.691(2) Å). The terminal S1-N1 and S2-N2 values are 1.553(10) and 1.550(8) Å, which are slightly longer than those of 5 (1.526(2) and 1.531 Å). Interestingly, the S1-C1-S2 angle of 116.8(2)° of 6 is almost the same as the corresponding angle of 5 (118.0(1)°), and is indicative of sp2 hybridization on the C1 atom. These findings suggest that the S1-C1-S2 bond has a double ylidic character such as carbodiphosphoranes, R3P=C=PR3.
