Coordination chemistry of dimethylgold halides with bidentate phosphorus and arsenic ligands - Revisited

Dimethylgold(III) chloride and bromide, (Me(2)AuX)(2), react with bis(diphenylphosphanyl)methane (dppm, molar ratio 1:2) to give the P-monohapto complexes cis-Me(2)AuX(dppm) (la, b) in quantitative yields. The products are readily oxidized by air to yield the P-hapto P'-monoxides 2a, b. Treatment of la, b with AgNO3 affords an ionic nitrate [Me(2)Au(dppm)](2) [NO3-](2) (1c), which contains a dinuclear cation. A mixed bromide/nitrate (from Ib and half the equivalent amount of AgNO3) is thermally unstable and undergoes elimination of ethane to give an ionic tetranuclear gold(I) complex [(dPPm)(4)Au4Br2](2+) [NO3-](2) (3b). - Treatment of (Me(2)AuCl)(2) with CH2(AsPh(2))(2) (dpam, molar ratio 1:2) gives cis-Me(2)-AuCl(dpam) (Id), the arsenic analog of la, which is not sensitive to oxygen. - The reaction of bis(diphenylphosphanyl)-amine (dppa) yields 1:1 P-monohapto adducts Me(2)-AuX(dppa), which are in equilibrium with ionic chelated systems Me(2)Au(dppa)(+) X(-) (1e, f). Complex le is readily oxidized by air to the P-hapto P'-monoxide cis complex 2e. Treatment of le with AgNO3 gives the ionic nitrate Met. Au(dppa)(+) NO3- (1g). - All compounds were identified by standard analytical and spectroscopic techniques. The crystal structures of 2a, 3b, Id, and 2e were determined by single-crystal X-ray diffraction studies.