Facile access to the eta2-alkyne-1-thio complexes [Tp'M(CO)2{eta2-(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{eta2-(BnS)CC(SBn)}](PF6), has been thoroughly investigated. Experimental evidence of the intermediates, [Tp'M(CO)2{eta2-(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}{eta2-(BnS)CC(SBn)}], is provided. Neutral eta2-alkyne-1-thio complexes [Tp'M(CO)2{eta2-(BnS)CC(S)}] bearing a free terminal sulfur atom have been established as monodentate ligands L in homoleptic pentanuclear [M'L4]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 eta2-CC-bound metal centers and the sulfur-coordinated metal ion.

The reaction of Cp 2 Ti(btmsa) [btmsa ) bis(trimethylsilyl)acetylene (Me 3 SiCtCSiMe 3 )] with bulky dichlorophosphines leads to the formation of diphosphenes or dichlorodiphosphines depending on the stoichiometry used. (Me 3 Si) 2 NN(SiMe 3 )PCl 2 (1) was transformed either into bis[tris(trimethylsilyl)hydrazino]dichlorodiphosphine (2) or bis[tris(trimethylsilyl)hydrazino]diphosphene (3) depending on whether an excess of 1 or Cp 2 Ti(btmsa) was used. Depending on the starting material ratios, Cp 2 TiCl 2 or (Cp 2 TiCl) 2 were obtained as byproducts besides 1 or 3. Compounds 2 and 3 were structurally characterized by X-ray diffraction. Furthermore, the known diphosphene Mes*PdPMes* (4) (Mes* ) 2,4,6-tri-tertbutylphenyl) and the dichlorodiphosphine Mes*(Cl)PP(Cl)Mes* (5) were prepared by reaction of Cp 2 Ti(btmsa) with Mes*PCl 2 . The reaction of Cp 2 Ti(btmsa) with the sterically less demanding PhPCl 2 resulted in the isolation of a triphosphinato complex. The diphosphine Ph 2 P-PPh 2 (6) was synthesized by reaction of Ph 2 PCl with Cp 2 Ti(btmsa).

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Rundherum mit Donor‐Elektronendichte ausgestattet ist das vieratomige Acetylendithiolat, das verschiedene Metalle als ambidenter Ligand elektronisch gekoppelt miteinander verknüpfen kann. Die flexible Abwinkelung der Schwefelatome im η2‐C,C′‐Acetylendithiolat‐Komplex [Tp′W(CO)2(η2‐C2S2)]− gestattet eine chelatartige Koordination beider Schwefeldonoren an das {(η5‐C5H5)Ru(PPh3)}‐Fragment (siehe Bild).

Acetylene disulfides RSC 2 SR, which are furnished with typical thiol protection groups R, were synthesized, fully characterized, and tested with respect to the aimed cleavage of R. While the alkyne RSC 2 SR with R = C 2 H 4 SiMe 3 is easily accessible, the corresponding disulfide with R = CPh 3 can be prepared only with difficulties, and attempts to use the SiMe 3 group lead to the isolation of a dithiacyclopentene derivative. The molecular structures of Ph 3 CSC 2 SCPh 3 and Ph 3 CSC 2 H, which were investigated by X-ray diffraction, show a remarkable combination of long and very short carbon-sulfur