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Supramolecular 3-/4-Mercaptobenzoic Acid Complexes of Palladium(II) and Platinum(II) Stabilized by Hydrogen Bonding



The reaction of cis-[Pt(PEt3)2(OTf)2] with 4-mercaptobenzoic acid (4-H2mba) in the presence of sodium methoxide yielded trans-[Pt(SC6H4COOH-4)2(PEt3)2] (1), the simple addition of 3-/4-mercaptobenzoic acid to cis-[Pt(PEt3)2(OTf)2] and cis-[M(PP)2(OTf)2] gave the self-assembled complexes cis-[Pt(μ-SC6H4COOH-n)(PEt3)2]2(OTf)2 [n = 3 (2), 4 (3)] and [M(μ-SC6H4COOH-n)(PP)]2(OTf)2 [M/n/PP = Pd/3/dppe (4), Pd/4/dppe (5), Pt/4/dppp (6); dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,2-bis(diphenylphosphino)propane], respectively, and the reactions of cis-[PtCl2(PR3)2] (R = Et, Ph) and [PtCl2(dppm)] with 3-/4-mercaptobenzoic acids in the presence of triethylamine yielded 1, trans-[Pt(SC6H4COOH-4)2(PPh3)2] (7) and [Pt(SC6H4COOH-n)2(dppm)] [n = 3 (8), 4 (9); dppm = bis(diphenylphosphino)methane], respectively. The complexes 14 and 7 form supramolecular assemblies through intermolecular hydrogen bonding in the solid state. A one-dimensional zigzag chain of carboxy dimers is formed in the structures ofH2O and 7, whereas methanol-interrupted large-ring formation leads to a 2D network for (MeOH)2. In the cases of (H2O)2 and (H2O)2, water and counter-anions assisted the formation of 1D networks rather than dimers through carboxylic acid groups.