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.