An electrospray mass spectrometry-directed survey of the coordination chemistry of the metalloligand [Pt 2(μ-S) 2(PPh 3) 4] with platinum(II) and palladium(II) chloride substrates: influence of metal–ligand lability on product type

Abstract

The reactivity of the metalloligand [Pt 2(μ-S) 2(PPh 3) 4] towards a wide range of platinum(II) and palladium(II) chloride complex substrates [L 2MCl 2] 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 ML 2 2+ fragment to the {Pt 2S 2} core, giving trinuclear species [Pt 2(μ-S) 2(PPh 3) 4ML 2] 2+. The adducts with Pt(diene) [diene=cyclo-octa-1,5-diene (cod), norbornadiene], Pd(cod), Pd(bipy) (bipy=2,2 ′-bipyridine), Pt(PMe 3) 2 and Pt(PTA) 2 (PTA=phosphatriaza-adamantane) moieties were synthesised and characterised on the macroscopic scale, with [Pt 2(μ-S) 2(PPh 3) 4Pt(cod)] (BF 4) 2 and [Pt 2(μ-S) 2(PPh 3) 4Pd(bipy)] (PF 6) 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 [Pt 2(μ-Se) 2(PPh 3) 4] and [Pt 2(μ-S) 2(dppe) 2] (dppe=Ph 2PCH 2CH 2PPh 2). With cis-[PtCl 2(SOMe 2) 2] the species [Pt 2(μ-S) 2(PPh 3) 4PtCl(SOMe 2)] + was formed, as a result of the lability of the SOMe 2 ligand. With palladium(II)-phosphine systems, the observed product species is dependent on the phosphine; the bulky PPh 3 ligand in [PdCl 2(PPh 3) 2] leads primarily to the analogous known species [Pt 2(μ-S) 2(PPh 3) 4PdCl(PPh 3)] +, and a small amount of the metal-scrambled species [PtPd 2S 2(PPh 3) 5Cl] +. In contrast, [PdCl 2(PTA) 2], containing the small PTA ligand gave [Pt 2(μ-S) 2(PPh 3) 4Pd(PTA) 2] 2+.