The reaction of [Mo(CBr)(CO)<sub>2</sub>(Tp*)] (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate)
with [Fe<sub>2</sub>(μ-SLi)<sub>2</sub>(CO)<sub>6</sub>] affords,
inter alia, the unsymmetrical binuclear thioxoethenylidene complex
[Mo<sub>2</sub>(μ,σ(<i>C</i>):η<sup>2</sup>(<i>C</i>′<i>S</i>)-CCS)(CO)<sub>4</sub>(Tp*)<sub>2</sub>], which may be more directly obtained from [Mo(CBr)(CO)<sub>2</sub>(Tp*)] and Li<sub>2</sub>S. The reaction presumably proceeds
via the intermediacy of the bis(alkylidynyl)thioether complex S{CMo(CO)<sub>2</sub>(Tp*)}<sub>2</sub>, which was, however, not directly observed
but explored computationally and found to lie 78.6 kJ mol<sup>–1</sup> higher in energy than the final thioxoethenylidene product. Computational
interrogation of the molecules [M<sub>2</sub>(μ-C<sub>2</sub>S)(CO)<sub>2</sub>(Tp*)<sub>2</sub>] (M = Mo, W, Re, Os) reveals
three plausible coordination modes for a thioxoethenylidene bridge
which involve a progressive strengthening of the C–C bond and
weakening of the M–C and M–S bonds, as might be expected
from simple effective atomic number considerations
