The Structure of Solid Copper(I) Cyanide:  A Multinuclear Magnetic and Quadrupole Resonance Study

Abstract

Carbon-13 and nitrogen-15 nuclear magnetic resonance (NMR) spectra of solid copper(I) cyanide present a clear picture of its molecular structure as comprising linear, polymeric chains: [−Cu−N−C−] n . Copper-63/65 nuclear quadrupole resonance reveals that the cyanide ligands are subject to “head-tail” disorder. Magic-angle spinning NMR spectra are analyzed by accounting for the quadrupolar effects of neighboring copper nuclei to yield one-bond indirect spin−spin coupling constants, 1 J ( 63 Cu, 13 C) ≈ +725 Hz and 1 J ( 63 Cu, 15 N) ≈ −250 Hz, and effective dipolar coupling constants, R eff ( 63 Cu, 13 C) ≈ +1200 Hz and R eff ( 63 Cu, 15 N) ≈ −460 Hz. The dipolar coupling data correspond to internuclear separations of r Cu,C ≈ 1.88 Å and r Cu,N ≈ 1.92 Å. The observation of axially symmetric 15 N and 13 C chemical shielding tensors in NMR spectra of nonspinning samples provides compelling evidence for the structural linearity of CuCN chains. Conclusions based on experimental data are supported by ab initio calculations of chemical shielding and electric field gradients.