Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXIX Syntheses, Spectroscopy and Structural Systematics of Some (Solvated) 1 : 2 Binuclear Adducts of Copper(I) Compounds with Triphenylarsine, [(Ph3As)2Cu(μ-X)2Cu(AsPh3)2], X = Cl, Br, ONO2

Abstract

1 : 2 Adducts of copper(I) chloride and bromide with triphenylarsine have been obtained as chloroform- solvated dimers [(Ph3As)2Cu(µ-X)2Cu(AsPh3)2].2CHCl3, characterized by room-temperature single- crystal X-ray studies, monoclinic C 2/c, a ≈ 21·4, b ≈ 17·9, c ≈ 19·3 Å, β ≈ 92°, Z = 4 dimers, conventional R on F being 0·041 and 0·055 for No 3922 and 3130 independent ‘observed’ (I > 3σ(I)) reflections; the halogen atoms of the dimers are disposed on crystallographic 2 axes, together with the associated hydrogen-bonded pair of disordered chloroform molecules. The structures form an interesting contrast with those of their silver(I)/phosphorus analogues, of similar symmetry but with a and c interchanged, as is the metal · · · metal axis orientation which, in each case, lies parallel to the long crystallographic axis. An unsolvated nitrate [(Ph3As)2Cu(µ-O-ONO2)2Cu(AsPh3)2], monoclinic, P 21/c, a 14·867(8), b 23·518(8), c 21·86(1) Å, β 122·24(4)°, Z = 4 dimers, R 0·056 for No 3447, is also recorded, the structure being similar to that of its silver(I) bromide analogue. The far-infrared spectra of [(Ph3As)2Cu(µ-X)2Cu(AsPh3)2].2CHCl3 (X = Cl, Br) show v(CuX) bands at 195 and 153 cm-1 respectively. Shifts in the wavenumbers of the CHCl3 vibrations which involve the hydrogen atom (or the deuterium atom in the corresponding CDC13 compounds) are in the direction expected for hydrogen bonding of the chloroform to the halide ligand, and the magnitudes of the shifts in these and the corresponding Ph3P/AgX complexes appear to be sensitive to the degree of ionic character of the M-X bonds. A combined differential scanning calorimetry/infrared study suggests that the chloroform disolvates are converted into unsolvated compounds which have the same halogen-bridged dimeric structures as the parent compounds, with v(CuX) = 184, 141 cm-1 for X = Cl, Br respectively.