Facile access to the eta(2)-alkyne-1-thio complexes [Tp'M(CO)(2) {eta(2)-(BnS) CC( S)}] (Tp' = hydrotris(3,5-dimethylpyrazolyl)borate; Bn = benzyl; M = Mo, W) by reductive removal of one benzyl group in the corresponding bis( benzylthio)acetylene complexes, [Tp ' M(CO)(2) {eta(2)-(BnS) CC(SBn)}](PF6), has been thoroughly investigated. Experimental evidence of the intermediates, [Tp' M(CO)(2) {eta(2)-(BnS) CC(SBn)}] (M = Mo, W), and the fate of the cleaved benzyl group by isolation of the byproduct, [Tp' W(CO) {C(O) Bn} {eta(2)-(BnS) CC(SBn)}], is provided. Neutral eta(2)-alkyne-1-thio complexes [Tp'M(CO)(2) {eta(2)-(BnS) CC(S)}] bearing a free terminal sulfur atom have been established as monodentate ligands L in homoleptic pentanuclear [M'L-4](2+) complexes with nickel( II) and palladium( II). Comparison of the NMR and IR spectroscopic as well as cyclovoltammetric data of the heterobimetallic complexes with the free thio-alkyne complexes reveals a strong electronic coupling of the redox-active eta(2)-CC-bound metal centers and the sulfur-coordinated metal ion.