Organoplatinum(IV) Complexes with Amide Groups: Supramolecular Structure as a Function of Ligand Flexibility

The oxidative addition of the benzyl bromide derivative 4-BrCH2C6H4(CH2)xC(=O)NH(CH2)y-4-C6H4-tBu (A), x = y = 0; (B), x = 0, y = 1; (C), x = 1, y = 0; (D), x = y = 1, to the dimethylplatinum(II) complex [PtMe2(bu2bipy)] (1), bu2bipy = 4,4′-di-tert-butyl-2,2′-bipyridine, gave the corresponding amide-substituted benzylplatinum(IV) complexes of the formula [PtBrMe2(4-CH2C6H4(CH2)xC(=O)NH(CH2)y-4-C6H4-tBu)(bu2bipy)], bu2bipy = 4,4′-di-tert-butyl-2,2′-bipyridine, 2–5. In the solid state, the complexes 2–5 undergo self-assembly to give the supramolecular polymers 2–4 or the dimers 5. Intermolecular N–H···Br-Pt hydrogen bonds are favored over the typical NH···O=C hydrogen bonds found in organic amides. The carbonyl group may be hydrogen-bonded to solvent or not involved in hydrogen bonding. The structures are dependent on the size and flexibility of the amide-substituted benzyl group. In solution, the complexes 3–5 exhibited an equilibrium between the neutral complexes and the bromo-bridged, ionic binuclear complexes [(μ-Br){PtBrMe2(4-CH2C6H4(CH2)xC(=O)NH(CH2)y-4-C6H4-tBu)(bu2bipy)}2]Br. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)