Synthesis and reactivity of half-sandwich type cobalt, rhodium and iridium complexes containing trithiocarbonate, dithiocarbonate, N-cyanodithiocarbimate, 1,1-dicyanoethylene-2,2-dithiolate and 1,1-dicyanoethylene-2,2-diselenolate as chelating ligands

A series of half-sandwich type complexes with [(C5R5)Co(L)] (R = H, Me; L = PR3, P(OR)3, CNR), [(C5R5)RhPR3′] (R = H, Me) and [(C5H5)Ir(PiPr3)] as building blocks and trithiocarbonate, dithiocarbonate, N-cyanodithiocarbimate, 1,1-dicyanoethylene-2,2-dithiolate and 1,1-dicyanoethylene-2,2-diselenolate as chelating ligands was prepared. They were characterized by mass spectrometry and IR, UV, and NMR spectroscopic techniques. The trithiocarbonate derivatives [(C5R5)Co(PMe3)(S2CS)] (R = H, Me) were oxidized with [Fe(C5H5)2]X (X = BF4, PF6) to the cationic compounds [(C5R5)Co(PMe3)(S2CS)]X. The oxidation potentials of the half-sandwich type complexes were determined by cyclovoltammetry. The reaction of [(C5Me5)Co(PMe3)(S2CS)] with tetracyanoethylene (TCNE) led to a ligand fragment exchange and gave the cobalt 1,1-dicyanoethylene-2,2-dithiolate [(C5Me5)Co(PMe3){S2CC(CN)2}] in good yield.

Graphical abstractHalf-sandwich type complexes of cobalt, rhodium, iridium and trithiocarbonate, dithiocarbonate, N-cyanodithiocarbimate, 1,1-dicyanoethylene-2,2-dithiolate, and 1,1-dicyanoethylene-2,2-diselenolate as chelating ligands were prepared and their oxidation potentials determined by cyclovoltammetry. While attempts to obtain 1:1 adducts between the title compounds and tetracyanoethylene (TCNE) failed, an unusual reaction occurred between a cobalt trithiocarbonate complex and TCNE leading to a cobalt 1,1-dicyanoethylene-2,2-dithiolate derivative by a ligand fragment exchange.Figure optionsDownload full-size imageDownload as PowerPoint slide