An electrospray mass spectrometry-directed survey of the coordination chemistry of the metalloligand [Pt2(μ-S)2(PPh3)4] with platinum(II) and palladium(II) chloride substrates: influence of metal–ligand lability on product type

The reactivity of the metalloligand [Pt2(μ-S)2(PPh3)4] towards a wide range of platinum(II) and palladium(II) chloride complex substrates [L2MCl2] has been explored, using the technique of electrospray ionisation mass spectrometry to directly analyse reaction solutions. In the majority of cases, products are formed by addition of the ML22+ fragment to the {Pt2S2} core, giving trinuclear species [Pt2(μ-S)2(PPh3)4ML2]2+. The adducts with Pt(diene) [diene=cyclo-octa-1,5-diene (cod), norbornadiene], Pd(cod), Pd(bipy) (bipy=2,2′-bipyridine), Pt(PMe3)2 and Pt(PTA)2 (PTA=phosphatriaza-adamantane) moieties were synthesised and characterised on the macroscopic scale, with [Pt2(μ-S)2(PPh3)4Pt(cod)] (BF4)2 and [Pt2(μ-S)2(PPh3)4Pd(bipy)] (PF6)2 also characterised by X-ray diffraction studies. No metal scrambling was found to occur, as has been observed in some previous cases involving the related complexes [Pt2(μ-Se)2(PPh3)4] and [Pt2(μ-S)2(dppe)2] (dppe=Ph2PCH2CH2PPh2). With cis-[PtCl2(SOMe2)2] the species [Pt2(μ-S)2(PPh3)4PtCl(SOMe2)]+ was formed, as a result of the lability of the SOMe2 ligand. With palladium(II)-phosphine systems, the observed product species is dependent on the phosphine; the bulky PPh3 ligand in [PdCl2(PPh3)2] leads primarily to the analogous known species [Pt2(μ-S)2(PPh3)4PdCl(PPh3)]+, and a small amount of the metal-scrambled species [PtPd2S2(PPh3)5Cl]+. In contrast, [PdCl2(PTA)2], containing the small PTA ligand gave [Pt2(μ-S)2(PPh3)4Pd(PTA)2]2+.