C-13 NUCLEAR MAGNETIC-RESONANCE STUDY OF COORDINATED THIOCYANATE, SELENOCYANATE, AND CYANATE

Carbon-13 chemical shifts have been measured for thiocyanate, cyanate, and selenocyanate in a variety of transition-metal complexes. The effects of cation and solvent changes upon the chemical shifts of the ionic pseudohalides have been determined. Changes in hybridization are more important than electron excitation energy changcs and substituent changes in determining chemical shifts, for both ionic and complexed species. The ordering of the ions in terms of increasing shielding is <OCN- <SeCN-. The ordering for thiocyanate and selenocyanate in terms of increasing shielding as a function of bonding mode is M-NCS(Se) < NCS(Se)- < M-S(Se)CN. The technique is therefore of considerable utility in the determination of the bonding mode adopted by these groups in solutions of the complexes. © 1979, American Chemical Society. All rights reserved.