Cyanide orientational ordering and copper electric field gradients in CuCN.N2H4.

The measurement of residual dipolar coupling in (13)C and (15)N MAS spectra of CuCN.N(2)H(4) allows for the extraction of (63/65)Cu quadrupole coupling constants (C(Q)((63)Cu) = 26 +/- 4 MHz). Ab initio calculations were employed to determine electric field gradient and chemical shielding tensor orientations, which proved essential for the reliable analyses of residual dipolar coupled (13)C and (15)N MAS spectra. The (1)J((63)Cu,(13)C) and (1)J((63)Cu,(15)N) couplings (590 and -120 Hz, respectively) indicate that the cyanide ligands are static and their magnitudes reflect the deviation of the C-Cu-N angle when compared with other copper cyanides. The observed (13)C and (15)N spectra are most compatible with a structural model wherein the cyanides are fully orientationally ordered: [-Cu-C-N-Cu-C-N-].