Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXV Synthesis, Spectroscopy and Structural Systematics of Some 1 : 3 Adducts of Copper(I) Compounds with Triphenylarsine, [(Ph3As)3CuX], X = Cl, Br, I, ONO2

Abstract

Crystallization of some copper(I) salts, CuX, with triphenylarsine in 1 : 3 stoichiometry from acetonitrile has yielded an array of adducts, [(Ph₃As)₃CuX], characterized by room-temperature single crystal X-ray structure determinations. [(Ph₃As)₃CuCl] (1) has been characterized in two unsolvated phases, α and β, the second form previously recorded as monoclinic, P2₁/n, Z = 8. The ‘α’ phase, like the bromide (2) and iodide (3), adopts the trigonal P3 array, widespread among many [(Ph₃E)₃MX] adducts with a ≈ 19, c ≈ 11 Å; conventional R on F was 0·037, 0·041, 0·056 for N_o 3458, 3259, 3434 independent ‘observed’ (I > 3σ(I)) reflections for these three adducts respectively. A further form, γ, is a toluene hemisolvate, monoclinic, P2₁/c, a 21·490(5), b 10·218(7), c 24·901(6) Å, β 117·53(2)°, Z = 4, R 0·057 for N_o 7207. The nitrate (4), obtained as a monosolvate from methanol, is monoclinic, P2₁/n, a 15 ·115(9), b 23·201(9), c 14·170(14) Å, β 92·56(7)°, Z = 4, R 0·049 for N_o 5476. In all compounds, the copper atom is four-coordinate, E₃CuX, the nitrate in (4) being -ONO₂ unidentate. The CuX bond lengthsr(CuX) in [(Ph₃E)₃CuX] (X = Cl, Br, I) show a decrease from the Ph3P to the corre₃sponding Ph3As compound, and this is consistent with the observed increase in the v(CuX) wavenumbers in the far-infrared spectra. These trends are both consistent with an increase in the CuX bond strength from the Ph₃P to the Ph₃As complexes, and possible reasons for this are discussed.