Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXX Synthesis, Spectroscopy and Structural Systematics of 1 : 2 Binuclear Adducts of Copper(I) Halides with Triphenylstibine, [(Ph3Sb)2Cu(-X)2Cu(SbPh3)2], X = Cl, Br, I

Abstract

Crystallization of 1 : 2 mixtures of the copper(I) halides CuX, X = Cl, Br, I, with triphenylstibine from acetonitrile yields adducts of 1 : 2 CuX/SbPh₃ stoichiometry, confirmed by single-crystal X-ray structure determinations. The three complexes are isomorphous, monoclinic, P 2₁/c, a ≈ 24·3, b ≈ 14·2, c ≈ 20 Å, β 110°, Z = 4 dimers; conventional R on F were 0·047, 0·044 and 0·045 for N_o 11247, 4673 and 10418 independent ‘observe’ (I > 3σ(I)) reflections respectively. The complexes, also isomorphous with some related species, e.g. 1 : 2 AgBr,I/AsPh₃, are dimers: [(Ph₃Sb)₂Cu(µ-X)₂Cu(SbPh₃)₂]. The chloride is also recorded as a chloroform disolvate, isomorphous with its arsine analogue, being monoclinic, C 2/c, a 21·486(9), b 17· 925(9), c 19·972(7) Å, β 91·31(3)°, Z = 4 dimers, R 0·057 for N_o 3756. The far-infrared spectra of [(Ph₃Sb)₂Cu(µ-X)₂Cu(SbPh₃)₂] (X = Br, I) showed no clear v(CuX) bands, in contrast to the situation reported previously for the corresponding Ph₃As compounds. A possible v(CuCl) band is observed in the X = Cl complex at 219 cm^-1 , but this occurs in a region where there is also significant absorption in the other two compounds. The absence of strong v(CuX) bands in these complexes is consistent with the situation observed previously for the 3 : 1 compounds [(Ph₃Sb)₃CuX].