STUDY OF QUADRUPOLE-PERTURBED QUARTETS IN THE SOLID-STATE MAGIC-ANGLE SPINNING P-31 NMR-SPECTRA OF PHOSPHINE CU(I) COMPLEXES - CU-63 ELECTRIC-FIELD GRADIENTS AND ANISOTROPY IN THE P-31,CU-63 SCALAR COUPLING

High-resolution solid-state P-31 NMR spectra of phosphine-containing Cu(I) complexes show field-dependent, distorted quartets in which the line separations are not constant. This phenomenon is due to the combination of scalar J(P-31,Cu-63) coupling with incompletely averaged dipolar and anisotropic J interactions. A simple analysis is presented on literature data involving a series of compounds of the P(n)CuX(m) type (P = triphenylphosphine and derivatives, X = halide) having different Cu coordination numbers and core geometries. It is concluded that the quartet distortion is related to structural data (P-Cu bond distances and ligand-Cu-ligand angles) and interesting molecular data (Cu-63 quadrupole coupling constants and anisotropy (DELTA-J) in the P-31,Cu-63 scalar coupling constant). In cases in which most of these data are available, DELTA-J can be obtained and shows a fairly constant value of ca. +0.6 kHz. Extension to other cases leads to the calculation of chi(Cu-63), both magnitude and sign. This information is discussed in light of a simple EFG analysis for the copper atom based on s-p hybridization schemes involving vacant Cu+ 4p orbitals.