Organoplatinum(IV) complexes with hydrogen bonds: From monomers to polymers

A series of organoplatinum(IV) complexes has been prepared, in which one of the alkyl groups contains a functional group that is capable of taking par t in hydrogen bonding. These complexes are formed by oxidative addition of reagents RCH2X to [PtMe2(bu(2)bipy)] (1; bu(2)-bipy = 4,4'-di-tert-butyl-2, 2'-bipyridine) and have the formula [PtXMe2(CH2R)(bu(2)bipy)] (2, R = CO2H, X = Br; 3, R = 4-C6H4CO2H, X = Br; 4, R = 4-C6H4CH2CO2H, X = Br; 6, R = C4 N2H3O2, X = Cl; 6, R = 4-C6H4NHCO2Me, X = Cl; 7, R = 2,4-C6H3(NHCO2Me)(2), X = Cl). These complexes may form dimers through OH ... O or NH ... O hydro gen bonding or polymers through NH ... X hydrogen bonding. Further derivati ves were prepared by reaction of the above complexes with AgBF4 in the pres ence of nicotinic acid or 4,4'-bipyridyl (bipy): namely, [PtMe2(CH2C6H4CO2H )(4-NC5H4CO2H)(bu(2)bipy)][BF4] (8) and [{PtMe2(CH2R)(bu(2)bipy)}(2)(mu-bip y)][BF4](2) (9a, R = C6H4CO2H; 10a, R = C6H4CH2CO2H) Complex 9a forms a pol ymer by OH ... O-hydrogen bonding, whereas 8 and 10a undergo hydrogen bondi ng with the solvent and/or the counterion. This work shows that extended st ructures can be designed with hydrogen bonding in organoplatinum compounds and that there is a fine balance between formation of dimers or polymers th rough OH ... O, NH ... O, or NH ... Cl bonding forms and formation of simpl er structures arising from hydrogen bonding to solvent molecules or counter ions.