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

Abstract

The measurement of residual dipolar coupling in ¹³C and ¹⁵N MAS spectra of CuCN·N₂H₄ allows for the extraction of ^63/65Cu quadrupole coupling constants (C_Q(⁶³Cu) = 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 ¹³C and ¹⁵N MAS spectra. The ¹J(⁶³Cu,¹³C) and ¹J(⁶³Cu,¹⁵N) 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 ¹³C and ¹⁵N spectra are most compatible with a structural model wherein the cyanides are fully orientationally ordered: [–Cu–C–N–Cu–C–N–].