Synthesis and reactions of dimethyltin dithiooxalate: a convenient dithiooxalate transfer reagent

Abstract

Dimethyltin dithiooxalate has been synthesised by the reaction of dimethyltin dichloride with potassium dithiooxalate. It may be used as a dithiooxalate (dto) transfer reagent, reacting with [PtL2Cl2] (L2 = 1,4-cyclooctadiene or 4,4′-bis(tert-butyl)-2,2′-bipyridine) to eliminate SnMe2Cl2 and form the corresponding platinum dithiooxalate compounds [Pt(COD)(dto)] 1 and [Pt(tBu2bipy)(dto)] 2. Reaction with the ruthenium compound [Ru(Me2bipy)(PPh3)2Cl2] 3 (Me2bipy = 4,4′-dimethyl-2,2′-bipyridine) does not proceed analogously however, eliminating from the ruthenium one chloride and one triphenylphosphine ligand, and thus producing not SnMe2Cl2 but “[SnMe2Cl]+”. This moiety becomes chelated within the dithiooxalate to produce the new ‘Coucouvanis’ type compound [cis-Ru(Me2bipy)(PPh3)Cl(μ-dto)(SnMe2Cl)] 4. Reaction of 4 with DMSO causes the elimination of SnMe2Cl2 by abstracting the tin centre and the second chloride ligand, producing cis-[Ru(Me2bipy)(PPh3)(DMSO)(dto)] 5. Upon treating 3 with [p-NNC6H4F][BF4] the oxidation product [Ru(Me2bipy)(PPh3)2Cl2][BF4] 6 is formed. 6 reacts with SnMe2(dto) to produce a second bimetallic complex, [Ru(Me2bipy)(PPh3)2(μ-dto)(SnMe2Cl)][BF4] 7a. The nature of the reduction products of 4 and 7 is explored, and the X-ray crystal structures of 2 and 5 are presented.