Tetrazolate rhodium(I) complexes. Crystal structures of the trinuclear complexes [Rh3(µ3-ttz)(µ-Cl)Cl(cod)2(CO)2](ttz = tetrazolate, cod = cyclo-octa-1,5-diene) and [Rh3(µ3-ttz)(µ-Cl)Cl(CO)6], an unusual example of metal–metal interactions

Abstract

Homo- and hetero-bridged binuclear complexes of general formulae [Rh2(µ-ttz)2(L2)2][ttz = tetrazolate, L2= diolefin or (CO)2] and [Rh2(µ-ttz)(µ-X)L2L′2][X = Cl, L2= L′2= diolefin; X = N3, L2= L′2= diolefin, L2= cyclo-octa-1,5-diene (cod), L′2=(CO)2] have been prepared. The heterobridged complexes, having unco-ordinated N atoms from the tetrazolate group, react with [Rh2(µ-Cl)2(L″2)2](2 : 1 molar ratio)[L″2= cod or (CO)2] to give trinuclear compounds of general formula [Rh3(µ3-ttz)(µ-X)ClL2L′2L″2](X = Cl or N3). The latter complexes can also be obtained by reaction of [Rh2(µ-ttz)2(L2)2] with [Rh2(µ-Cl)2(L′2)2](1 : 2 molar ratio). X-Ray crystallographic studies of the complexes [Rh3(µ3-ttz)(µ-Cl)Cl(cod)2(CO)2](12) and [Rh3(µ3-ttz)(µ-Cl)Cl(CO)6](13) show them to contain trinuclear units, with bridging Cl atoms and tetrazolate groups. In complex (13) the units pack in the crystal with infinite chains, through Rh ⋯ Rh interactions of 3.457(2), 3.229(2), and 3.399(2)Å. In compound (12) the complex consists only of two units, related by a symmetry centre with a Rh ⋯ Rh distance equal to 3.519(2)Å.