The self-assembly of organoplatinum(IV) complexes to give supramolecular polymers and network materials is described, using the ligand ethyl 5 0 -[(ethoxycarbonyl)amino]-2,2 0 -bipyridine-5-carboxylate (1), which contains the EtOC(dO)NH-hydrogen bonding donor group. Ligand 1 reacts with [Pt 2 Me 4 (μ-SMe 2 ) 2 ] to give [PtMe 2 (1)] (2), which forms a supramolecular polymer in the solid state through formation of intermolecular NH 3 3 3 OdC hydrogen bonds with further selfassembly to a sheet structure through π-stacking. Oxidative addition of bromomethyl compounds RCH 2 Br to complex 2 gave the corresponding organoplatinum(IV) complexes [PtBrMe 2 (CH 2 R)(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 3 3 3 OdC hydrogen bonds, some complexes formed hydrogen bonds to solvent molecules NH 3 3 3 O (solvent) or to coordinated bromide NH 3 3 3 BrPt or a combination of π-stacking with CH 3 3 3 Br hydrogen bonding. New forms of self-assembly in organometallic compounds were identified, one involving polymerization through intermolecular NH 3 3 3 Br 3 3 3 HN supramolecular chelation and one involving a combination of NH 3 3 3 OdC and CH 3 3 3 Br hydrogen bonding along with π-stacking to form a network composed of multiply intercalated sheets.

The oxidative addition of 4-BrCH(2)C(6)H(4)-C(=O)NH-t-Bu to [PtMe(2)(bu(2)bipy)], bu(2)bipy = 4,4'-di-tert-butyl-2,2'-bipyridine, gave [PtBrMe(2)(CH(2)C(6)H(4)-C(=O)NH-t-Bu)(bu(2)bipy)], which reacted with AgX and a bridging ligand LL to give binuclear complexes [{PtMe(2)(CH(2)C(6)H(4)-C(=O)NH-t-Bu)(bu(2)bipy)}(2)(mu-LL)]X(2), LL = 1,4-pyrazine or 4,4'-bipyridine, X = BF(4) or PF(6). The complexes all take part in hydrogen bonding through either NHO[double bond]C, NHFB or NHFP interactions and, in the case with LL = 4,4'-bipyridine, X = PF(6), a supramolecular structure containing tubes is formed.

Oxidative addition reactions of R,R′-dibromo-o-xylene, -m-xylene, and -p-xylene to two units of [PtMe 2 (bu 2 bipy)], bu 2 bipy ) 4,4′-di-t-butyl-2,2′-bipyridine, give the corresponding binuclear organoplatinum(IV) complexes with bridging xylenediyl groups, [C 6 H 4 {CH 2 PtBrMe 2 (bu 2 bipy)} 2 ]. Oxidative addition of C 6 -1,3,5-Me 3 -2,4,6-(CH 2 Br) 3 to three units of [PtMe 2 (bu 2 bipy)] gave the triplatinum(IV) complex [C 6 -1,3,5-Me 3 -2,4,6-{CH 2 PtBrMe 2 (bu 2 bipy)} 2 ]. In the sterically congested complexes 1,2-[C 6 H 4 {CH 2 PtBrMe 2 (bu 2 bipy)} 2 ] and [C 6 -1,3,5-Me 3 -2,4,6-{CH 2 PtBrMe 2 (bu 2 bipy)} 2 ], there is restricted rotation of the xylylplatinum groups. Bromide abstraction from the binuclear bromoplatinum(IV) complexes with AgPF 6 , 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 PO 2 F 2 -, HPO 3 F -, or H 2 PO 4 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.

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)

The synthesis and self-assembly of organoplatinum(IV) complexes containing both a carboxylic acid and an amide group is described. The complex [PtMe2(1)], in which the ligand 1 is the unsymmetrical 2,2′-bipyridine derivative ethyl 5′-[(ethoxycarbonyl)amino]-2,2′-bipyridine-5-carboxylate, undergoes oxidative addition to give chiral and racemic (C/A=clockwise/anticlockwise) organoplatinum(IV) complexes. The most predictable form of self-assembly was through π-stacking, which always connected pairs of molecules of opposite chirality (C/A). The complex [PtMe2(1)] reacted with bromoacetic acid to give [PtBrMe2(CH2CO2H)(1)], which exists as a mixture of three isomers, of which the trans isomer forms a supramolecular network material through a combination of intermolecular NH···OC, OH···O, OH···Br, and CH···Br hydrogen bonding, with support through π-stacking between bipyridyl groups 1. The platinum(IV) complexes [PtBrMe2(4-CH2C6H4(CH2) n CO2H)(1)], n=0 or 1, form a supramolecular polymer (n=0) or double-stranded polymer (n=1) through a combination of hydrogen bonding and π-stacking. Reaction of these organoplatinum(IV) complexes with AgPF6 and the pyridine-derived ligand L=3,5-C5H3N(CO2H)2 gave the corresponding cationic complexes [PtMe2(CH2C6H4(CH2) n CO2H)(1)L]+, as the hexafluorophosphate salts. Hydrolysis of the ion [PF6]− to form [PO2F2]− occurred during recrystallization, and the supramolecular structures were dominated by hydrogen bonding between carboxylic acid groups and the [PO2F2]− ions through units CO2H···OPF2O···HO2C. The self-assembly occurs selectively, and individual supramolecular polymer chains may contain C−C−C-C, A−A−A−A, or C−A−C−A groupings.