Thioethers from thiolate ions

The [Mo(NO)(S4)] fragment yielded a series of three complexes with formal 16, 17, and 18 VE counts (Fig. 10). Although the chloro complex [Mo(C1)(NO)(S4)] potentially can be considered an 18 VE species due to n donation from the chloride ion (see above), the different electronic situations in the three complexes are clearly reflected by the v(NO) frequencies. However, there are no antibonding electrons, and the Mo— S (and other Mo donor) bond distances stay in the usual range. In addition, while Mo—S(thiolate) and Mo—S(thioether) distances in different [Mo(S4)] complexes can vary considerably, the respective Mo—S distances in [Mo(C1)(NO)(S4)J, [Mo(PMe3)(NO)-(S4)], and [Mo(NO)2(S4)] are very similar. Figure 10 summarizes these results and correlations (108, 109). 

---