An investigation of the coordination chemistry of the mercaptocarboxylate ligands 3-mercaptopropionate and 5-mercapto-1H-tetrazole-1-acetate

Abstract

Complexes of the mercaptocarboxylate ligands 5-mercapto-1H-tetrazole-1-acetate (MTA) and 3-mercaptopropionate (MPA) with platinum(II), palladium(II), nickel(II), gold(I) and mercury(II) centres have been synthesised and characterised. In the presence of ancillary phosphine ligands, the platinum, palladium and nickel complexes contain bidentate S,O-chelating ligands, while in MTA complexes of PhHg+ and Ph3PAu+, the ligand is monodentate and S-bonded. However, in marked contrast, the palladium MTA and MPA complexes containing a 1,10-phenanthroline (phen) ligand are dinuclear, thiolate-bridged, zwitterionic complexes i.e. [Pd2(μ-MTA)2(phen)2] and [Pd2(μ-MPA)2(phen)2]·7H2O. Interestingly, the complexes of both ligands displayed fragmentation patterns of CO2 loss and CS bond cleavage while the MTA systems also gave peaks for N2 loss from the tetrazole ring in ESI MS. X-ray structure determinations of [Pt(MPA)(PPh3)2] and [Pd2(μ-MPA)2(phen)2]·7H2O are also reported.