Structural and spectroscopic studies on three- and two-co-ordinate copper(I) halide tribenzylphosphine complexes

Three-co-ordinate, monomeric 1 : 2 complexes of tribenzylphosphine (PBz(3)) with copper(I) halides, [Cu(PBz(3))(2)X] (X = Cl, Br or I), have been synt hesized and characterized by single crystal structure determinations, solid state P-31 CPMAS NMR spectroscopy and low frequency vibrational spectrosco py. The two PBz(3) ligands show different conformational structures and thi s is reflected in a distorted 'P2CuX' geometry for each complex. Solid stat e P-31 CPMAS spectra show asymmetric quartets with (1)J(P-31-Cu-63) ranging from 1.23 to 1.46 kHz and asymmetry parameters, d nu (Cu), ranging from 8 x 10(9) to 13 x 10(9) Hz(2). Reported also are the synthesis, structure, so lid state P-31 NMR and far-IR spectra of the two-co-ordinate complex [Cu(PB z(3))(2)][CuCl2] and the crystal structure of the dimeric 1 : 1 chloride co mplex, [Cu-2(PBz(3))(2)Cl-2]. 3C(6)H(6), this latter structure being the fi rst of this type reported for the PBz(3) ligand. Attempts to synthesize a 1 : 1 chloro complex using acetonitrile, rather than chloroform, as solvent led to the formation of tribenzylphosphine oxide. The conversion of [Cu-2(P Bz(3))(2)Cl-2]. 3C(6)H(6) into [Cu(PBz(3))(2)][CuCl2] upon removal of benze ne of solvation was followed by far-IR spectroscopy. The vibrational spectr a of the bulk 1 : 1 and 1 : 2 complexes are consistent with the crystal str uctures. Bands due to the nu (CuX) modes of the neutral complexes and those due to the [CuX2](-) ions in the ionic complexes have been assigned, and t he relationship between the spectra and the structures of the compounds is discussed.