Acetylenedithiolate as directional bridging ligand in cobalt(I) alkyne platinum dithiolato bimetallic complexes

The eta(2)-C,C-acetylenedithiolate (acdt2-) complex K[(triphos)Co(acdt)], K-5, {triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane} was obtained by consecutive removal of S-protection groups in [(triphos)Co(1)]PF6, 3-PF6 (1 = 1-Trimethylsilyl-7-phenyl-3,6-dithiahept-4-ine). Reaction of K-5 with selected Pt(II) salts resulted in the formation of the new heterobimetallic complexes [(phen)Pt(5)]BPh4, 6-BPh4, (phen = 1,10-phenanthroline) and [(dppe)Pt(5)]BPh4, 7-BPh4, {dppe = 1,2-bis(diphenylphosphino)ethane}, which were fully characterized. X-ray diffraction studies showed that Co and Pt are linked by acdt2- in the eta(2)-C,C-2-S,S-bridging mode. The electronic structure of 6-BPh4 and 7-BPh4 was investigated by electronic absorption spectroscopy, cyclic voltammetry and X-band EPR spectroscopy of neutral 7. In addition, NMR spectroscopy, X-ray diffraction and reactivity studies with the alkyne complexes [(PMe3)3Co(1)]-PF6, 2-PF6, with 3-PF6 and the intermediate product [(triphos)Co{eta(2)-(S)C2(SCH2Ph)}], 4, uncovered the flexibility of the CoC2S2-moiety within the persisting complex scaffold throughout the synthetic scheme.