Structural and vibrational spectroscopic studies of complexes of trimethylphosphine with copper(I) and silver(I) halides

Abstract

New copper(I) halide–trimethylphosphine adducts were prepared by reaction of CuX with PMe3 in benzene suspension, and characterized by room-temperature single-crystal X-ray studies and vibrational spectroscopy. [(Me3P)2Cu(µ-I)2Cu(PMe3)2], monoclinic, space group P21/c, a= 9.296(2), b= 16.206(7), c= 9.577(3)A, β= 113.76(2)°, Z= 2 dimers, conventional R on |F| 0.040 for 1369 ‘observed’[I > 3σ(I)] reflections at convergence; [{Cu4Cl4(PMe3)3}∞], rhombohedral, space group R3c, a= 17.776(2), c= 11.708(7)A(hexagonal setting), Z= 6, R= 0.045 for 820 observed reflections. The latter is a novel one-dimensional polymer of quasi-cubanoid Cu4Cl4 units disposed with their body diagonals coincident with the crystallographic 3-axis and linked by Cu–Cl bonds between the four-co-ordinate apical atoms of successive Cu4Cl4 units. Unlike the related [{Cu4I4(NEt3)3}∞] polymer, however, the off-axis copper atoms are planar three- rather than four-co-ordinate, having (µ-Cl)2CuP environments. The far-IR and Raman spectra of the compounds, and of the 1 : 1 Agl–PMe3 complex with the proposed tetrameric ‘cubane’ structure [Ag4I4(PMe3)4], have been recorded and assigned. The frequencies and activities of the v(MX) modes correlate well with the observed or proposed structures, and a comparison of the Raman spectra for the series of three compounds allows the first rational assignment of v(MP) modes for multinuclear complexes of this type.