Nuclear quadrupolar coupling constants in the cyanoborohydride ion: T 1 measurements and ab initio molecular orbital calculations

The 11 B and 2 H spin–lattice relaxation times, T 1 , were measured for sodium cyanoborohydride (BH 3 CN − ) and sodium cyanoborodeuteride (BD 3 CN − ) in methanol–ethylene glycol solution as a function of temperature. Both 11 B and 2 H T 1 minima were observed, yielding 11 B and 2 H nuclear quadrupolar coupling constants, χ, of 766 and 104 kHz, respectively. Measurement of the 14 N T 1 at 300 K gave a χ( 14 N) value of 2.8 MHz. Electric field gradients were calculated using ab initio molecular orbital theory, in order to obtain theoretical 11 B, 14 N and 2 H χ values. The values of 847 kHz, −3.25 MHz and 141 kHz for 11 B, 14 N and 2 H, respectively, are larger than those found in solution.