Trapping of a Late-Metal Terminal Sulfido Intermediate with Phenyl Isothiocyanate

Nickel-sulfur bonds play key roles in catalysis and biological systems. In most metal complexes, sulfur acts as a bridge joining metal centers, rather than as a terminal sulfide ligand. The addition of phenyl isothiocyanate to Ni(dcpe)(Ph)(SH) afforded the dithiocarbamate complex Ni(dcpe)(kappa(2)-S2C=NPh) with the loss of benzene. The reaction was monitored by UV-visible spectroscopy under pseudo-first-order rate conditions and showed limited dependence on isothiocyanate concentration, suggesting that the reaction proceeds through an intermediate terminal sulfido nickel complex. The values of Delta H-double dagger and Delta S-double dagger for the reaction were found to be 18.6 +/- 1.5 kcal/mol and -17.8 +/- 4.7 eu, respectively. Full characterization of Ni(dcpe)(kappa(2)-S2C=NPh), including a single-crystal X-ray structure determination, was achieved.

Automated summary

Nickel-sulfur bonds are important in catalysis and biological systems. This study synthesized and characterized a new nickel complex, providing insight into its reaction mechanism.