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 N_o 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 N_o 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.