Ruthenium terpyridine complexes with mono- And bi-dentate dithiolene ligands

The reaction of [Ru(CO)₂Cl(terpy)]PF₆ (terpy = 2,2′:6′:2″-terpyridine) with Na₂mnt (mnt = S₂C₂(CN)₂) initially produced [Ru(CO)₂(mnt-κS)(terpy-κ³NN′N ″)] 1a, which rearranged to [Ru(CO)₂(mnt-κ²SS′)(terpy-κ ²NN′)] 1b in solution. The molecular structures of 1a and 1b indicate that the rearrangement proceeds via a five-coordinated complex with monodentate mnt and bidentate terpy. The reaction of [Ru(CO)₂Cl(terpy)]PF₆ with 3,4-toluenedithiol (H₂tdt) gave [Ru(CO)₂(tdt-κ²SS′)(terpy-κ ²NN′)] 2b but [Ru(CO)₂(tdt-κS)(terpy-κ³NN′N ″)] 2a was not identified. Thus, ruthenium complexes with bidentate dithiolene and bidentate terpyridine seem to be more stable than those with monodentate dithiolene and tridentate terpyridine. Neither [Ru(CO)₂(pdt-κS)(terpy-κ³NN′N ″)] 3a nor [Ru-(CO)₂(pdt-κ²S)(terpy-κ² NN′)] 3b (pdt = PhC(S)C(S)Ph) was obtained in the reaction of [Ru(CO)₂Cl(terpy)]PF₆ with the Cs⁺ salt of pdt^2- in CH₃OH under N₂. The same reaction conducted under aerobic conditions afforded [Ru(CO)(C(O)OCH₃)(SC(Ph)C(Ph)SC(O)OMe)(terpy-κ³ NN′N″)] 3 resulting from double addition of CO₂ and CH₃OH to the terminal sulfur of pdt and a carbonyl carbon of 3a, respectively, followed by esterification of the resultant [Ru(CO)(C(O)OCH₃)(SC(Ph)C(Ph)SC(O)OH)(terpy-κ³ NN′N″)] in CH₃OH. The addition of CO₂ to the sulfur of 3a is ascribed to the strong basicity and weak chelating ability of pdt compared with those of mnt and tdt. A series of [RuX(dithiolene)(terpy)]ⁿ⁺ (X = dmso, Cl or OSO₂CF₃; n = 0 or 1) were also prepared.