Mono- versus bidentate coordination of the NONOate [Et2N(N2O2)]- to copper(II) complexes of tetradentate ligands
作者:Jamie L. Schneider、Jason A. Halfen、Victor G. Young, Jr.、William B. Tolman
DOI:10.1039/a800561c
日期:——
Copper(II) complexes of [Et2N(N2O2)](-) with tetradentate, tripodal ligands composed of 1,4,7-triazacyclononanes with pyridine (L-Py), amide (L-HAmH) Or phenolate (L-R2, R = Me, or Bu-t phenolate substituents) groups as the fourth donor were prepared and characterized by spectroscopic and X-ray crystallographic methods. Bidentate O,O-coordination of [Et2N(N2O2)](-) was observed in the complexes supported by L-Py and L-HAmH, but the stronger phenolate donor in L-R2 induced novel monodentate coordination via the terminal oxygen atom, defined by X-ray crystallography for R = Bu-t. Comparison of the bonding parameters of [Et2N(N2O2)](-) when bound bidentate vel sus when bound monodentate revealed subtle but significant differences in the N-O distances. The amount and rate of nitric oxide (NO) release from the compounds was measured using a chemiluminescence detection method. Despite the differences in [Et2N(N2O2)](-) structural parameters resulting from the divergent coordination modes, insignificant variation of the rates of NO release therefrom were found.