1,1-Ethylenedithiolato Complexes of Palladium(II) and Platinum(II) with Isocyanide and Carbene Ligands

The reactions of [Tl2{S2CC{C(O)Me}2}]n with [MCl2(NCPh)2] and CNR (1:1:2) give complexes [M{η2-S2CC{C(O)Me}2}(CNR)2] [R = tBu, M = Pd (1a), Pt (1b); R = C6H3Me2-2,6 (Xy), M = Pd (2a), Pt (2b)]. Compound
1b reacts with AgClO4 (1:1) to give [{Pt(CNtBu)2}2Ag2{μ2,η2-(S,S‘)-{S2CC{C(O)Me}2}2}](ClO4)2 (3). The reactions
of 1 or 2 with diethylamine give mixed isocyanide carbene complexes [M{η2-S2CC{C(O)Me}2}(CNR){C(NEt2)(NHR)}] [R = tBu, M = Pd (4a), Pt (4b); R = Xy, M = Pd (5a), Pt (5b)] regardless of the molar ratio
of the reagents. The same complexes react with an excess of ammonia to give [M{η2-(S,S‘)-S2CC{C(O)Me}2}(CNtBu){C(NH2)(NHtBu)}] [M = Pd (6a), Pt (6b)] or [M{η2-(S,S‘)-S2CC{C(O)Me}2}{C(NH2)(NHXy)}2] [M = Pd
(7a), Pt (7b)] probably depending on steric factors. The crystal structures of 2b, 4a, and 4b have been determined.
Compounds 4a and 4b are isostructural. They all display distorted square planar metal environments and chelating
planar E,Z-2,2-diacetyl-1,1-ethylenedithiolato ligands that coordinate through the sulfur atoms.