Binuclear Organoplatinum(IV) Complexes with Bridging Xylenediyl Groups: Formation of Supramolecular Polymers through Hydrogen Bonding

Oxidative addition reactions of α,α′-dibromo-o-xylene, -m-xylene, and -p-xylene to two units of [PtMe2(bu2bipy)], bu2bipy = 4,4′-di-t-butyl-2,2′-bipyridine, give the corresponding binuclear organoplatinum(IV) complexes with bridging xylenediyl groups, [C6H4{CH2PtBrMe2(bu2bipy)}2]. Oxidative addition of C6-1,3,5-Me3-2,4,6-(CH2Br)3 to three units of [PtMe2(bu2bipy)] gave the triplatinum(IV) complex [C6-1,3,5-Me3-2,4,6-{CH2PtBrMe2(bu2bipy)}2]. In the sterically congested complexes 1,2-[C6H4{CH2PtBrMe2(bu2bipy)}2] and [C6-1,3,5-Me3-2,4,6-{CH2PtBrMe2(bu2bipy)}2], there is restricted rotation of the xylylplatinum groups. Bromide abstraction from the binuclear bromoplatinum(IV) complexes with AgPF6, followed by the addition of a pyridine ligand with one or two carboxylic acid functional groups, gave binuclear organoplatinum(IV) compounds containing at least two carboxylic acid groups, with the potential to polymerize through intermolecular hydrogen-bonding interaction in the solid state. During crystallization of the platinum(IV) complexes, hydrolysis of the hexafluorophosphate anions occurred to give PO2F2−, HPO3F−, or H2PO4− anions, and these were found to take part in hydrogen bonding with the carboxylic acid groups or to displace the functionalized pyridine ligand. Several binuclear organoplatinum(IV) complexes and supramolecular polymers were structurally characterized.