Variations in the Coordination Sphere of Ruthenacyclic Carbamoyl Complexes: Mapping Their Suitability for Direct Conjugation

The reactivity of a series of ruthenacyclic carbamoyl derivatives <b>4x</b>, which are structural mimics of the [Fe]-hydrogenase metal cofactor, have been assessed in relation to their suitability for direct conjugation onto peptides. Substitution of a bromido ligand is specific for thiolates and selenolates, offering direct conjugation and precise control of the conjugation site. The ligand <i>trans</i> to the carbamoyl moiety is labile and, in certain solvents, may be uncoordinated. Steric effects from substitution at the 6-position of the aminopyridyl ring, or of the thiolato ligand in the thiolated derivatives, influence isomerization and dimerization, as well as efficacy and selectivity in catalytic organosilane hydrolysis.