Supramolecular Organoplatinum(IV) Chemistry: Sequential Introduction of Amide Hydrogen Bonding Groups

The self-assembly of organoplatinum(IV) complexes to give supramolecular polymers and network materials is described, using the ligand ethyl 5′-[(ethoxycarbonyl)amino]-2,2′-bipyridine-5-carboxylate (1), which contains the EtOC(O)NH− hydrogen bonding donor group. Ligand 1 reacts with [Pt2Me4(μ-SMe2)2] to give [PtMe2(1)] (2), which forms a supramolecular polymer in the solid state through formation of intermolecular NH···OC hydrogen bonds with further self-assembly to a sheet structure through π-stacking. Oxidative addition of bromomethyl compounds RCH2Br to complex 2 gave the corresponding organoplatinum(IV) complexes [PtBrMe2(CH2R)(1)], in which the group R could contain a further hydrogen bonding carboxamide group, and the organoplatinum(IV) complexes with two hydrogen-bond donor groups could form either supramolecular polymers or sheet structures through hydrogen bonding. As well as the anticipated NH···OC hydrogen bonds, some complexes formed hydrogen bonds to solvent molecules NH···O(solvent) or to coordinated bromide NH···BrPt or a combination of π-stacking with CH···Br hydrogen bonding. New forms of self-assembly in organometallic compounds were identified, one involving polymerization through intermolecular NH···Br···HN supramolecular chelation and one involving a combination of NH···OC and CH···Br hydrogen bonding along with π-stacking to form a network composed of multiply intercalated sheets.