Lewis-base adducts of Group 11 metal(I) compounds. Part 27. Solid-state phosphorus-31 cross-polarization magic-angle spinning nuclear magnetic resonance, far-infrared, and structural studies on the mononuclear 2 : 1 adducts of triphenylphosphine with copper(I) and gold(I) halides

Abstract

Single-crystal X-ray diffraction structure determinations, high resolution solid-state cross-polarization magic-angle spinning ³¹P n.m.r., and far-i.r. spectral data are reported for the mononuclear 2 : 1 adducts of triphenylphosphine with copper(I) and gold(I) halides, [M(PPh₃)₂X]. Crystal data are reported for [Cu(PPh₃)₂Cl]·0.5C₆H₆, [Cu(PPh₃)₂l], [Au(PPh₃)₂Cl](unsolvated), [Au(PPh₃)₂Br], and [Au(PPh₃)₂l]. In each structure the PPh₃ ligands adopt an eclipsed conformation about M–P with respect to M–X, with X–M–P–C(11) conformational angles ranging from 0.5 to 18.3°. Within each halide series, M–P distances and P–M–P angles are independent of halogen [CuCl: 2.272(2), 2.260(2)Å, 125.48(7)°; Cul: 2.273(2)Å, 126.9(1)°; AuCl (unsolvated): 2.336(4), 2.317(4)Å, 135.7(1); AuBr: 2.323(2)Å, 132.45(8)°; and Aul: 2.333(2)Å, 132.13(7)°]. Considerable asymmetry (490–560 Hz) in the solid-state ³¹P n.m.r. quartets obtained for M = Cu reflects the lower symmetry of the copper environment relative to four-co-ordinate tetrahedral compounds. Solid-state ³¹P chemical shift data for M = Au are independent of halogen (Cl, 37; Br, 38; I, 36 p.p.m.). The far-i.r. spectrum of [Cu(PPh₃)₂l] reveals a strong band at 184 cm^–1 which is assigned to the Cul terminal stretching mode.