Reactivity of bis(diphenylphosphines)digold(I) dications with azotate neutral heterocycles:: X-ray crystal structure of eclipsed [μ-dppmAu2(pzH)2]2+•2ClO4-•H2O and staggered [μ-dppeAu2(pzH)2]2+•2ClO4- complexes

Dinuclear gold(I) dicationic complexes were prepared reacting [mu-dpp(CH2)(n)Au-2](2+) (dpp(CH2)(n) = bis(diphenylphosphine)alkane; n = 1, 2, 3) with azotate neutral heterocycles. Using 3,5-dimethylpyrazole (pzH) as ancillary ligand and ClO4- as counterion, insoluble polymeric species were obtained by a kinetic control of the reactions; extractions by hot chloroform yield the corresponding monomeric derivatives [mu-dpp(CH2)(n)Au-2(pzH)(2)](2+) . 2ClO(4)(-) (I, IIa, III). In one case using NO3- instead of ClO4- anion the monomeric specie (IIb) was directly obtained. Using as neutral coordinating ligand bis(imidazo-2-yl)methane (BIMH2), ten- and 11-membered heterobridged cyclic derivatives [mu-dpp(CH2)(n)Au(2)mu-BIMH2](2+) . 2ClO(4)(-) (IV, V) were also obtained. P-31-NMR spectrum of (IV) revealed partial and complete opening of the cycle in solution. The X-ray crystal structures of [mu-dppmAu(2)(pzH)(2)](2+) . 2ClO(4)(-) . H2O (I) and [mu-dppeAu(2)(pzH)(2)](2+) . 2ClO(4)(-) (IIa) are reported ((I): monoclinic, space group P2(1)/n, a = 12.253(4), b = 19.417(3), c = 19.152(2) Angstrom, beta = 97.90(2)degrees, Z = 4; (IIa): monoclinic, space group P2(1)/n, a = 10.997(3), b = 13.629(2), c = 14.812(2) Angstrom, beta = 104.63(1)degrees, Z = 2). The short intramolecular Au ... Au distance of 3.133(2) Angstrom found in complex (I) indicates a metal-metal interaction. (C) 1999 Elsevier Science S.A. All rights reserved.