SYNTHESIS, CRYSTAL-STRUCTURES AND DYNAMIC NMR-STUDIES OF NOVEL TRINUCLEAR COPPER(I) HALIDE-COMPLEXES WITH 2,5-BIS[(DIPHENYLPHOSPHINO)-METHYL]THIOPHENE

Novel trinuclear copper(I) halide complexes with 2,5-bis[(diphenylphos phino)methyl]thiophene (dpmt), [Cu-3(mu(3)-X)(mu-X)(2)(mu-dpmt)(2)] (X = I 1, Br 2 or Cl 3), have been synthesized and structurally characte rised. They have unusual three-runged ladder structures with one tripl e-bridging and two double-bridging halide atoms. Two of the Cu-I are t etrahedrally co-ordinated and one, in the middle of the structure unit , has trigonal co-ordination geometry. The trinuclear Cu-3(mu(3)-X)(mu -X)(2) framework shows some changes with halide anion X due to the siz e effect and intramolecular non-bonding Cu ... Cu and X ... X interact ions. The NMR studies showed that the trinuclear framework is retained in solution for 1 (X = I), is in equilibrium with Cu-3(mu-X)(3) for 2 (X = Br) and changes to Cu-3(mu-Cl)(3) for 3 (X = Cl), an effect attr ibutable to the decrease of halide size from iodide to chloride. The f rameworks in the solutions of 2 and 3 exhibit fluxional behaviour invo lving bromine and chlorine mobility respectively.