Ruthenium complexes with a terminal hydrazido ligand. Synthesis, spectroscopy, and X-ray crystal structure

Abstract

Bis(1,1-diphenylhydrazido(1-))ruthenium(IV) porphyrins, [Ru(IV)(Por)(NHNPh 2) 2] (Por = TPP, TTP, 4-Cl-TPP, 4-MeO-TPP), were prepared in ~60% yields through the reaction of dioxoruthenium(VI) porphyrins, [Ru(VI)(Por)O 2], with 1,1-diphenylhydrazine in ethanol. This new type of ruthenium complex has been characterized by 1H NMR, IR, UV-vis, and FABMS with elemental analysis. The crystal structure of [Ru(IV)(TTP)(NHNPh 2) 2], which reveals an η 1-coordination mode for both hydrazido axial ligands, has been determined. The average Ru-NHNPh 2 distance and Ru-N-N angle were found to be 1.911(3) Å and 141.1(3)°, respectively. The porphyrin ring exhibits a ruffling distortion that is unprecedentedly large for ruthenium complexes with simple porphyrinato ligands (such as TTP). This is probably due to the steric effect of the axial hydrazido(1-) ligands.