Tricarbonylmanganese(I) and -rhenium(I) Complexes of Imidazol-Based Phosphane Ligands: Influence of the Substitution Pattern on the CO Release Properties

Tricarbonylmanganese(I) and -rhenium(I) complexes of the imidazolylphosphane ligands tris(imidazol-2-yl)phosphane (2-TIPH), tris(N-methylimidazol-2-yl)phosphane (2-TIPNMe), and tris[2-isopropylimidazol-4(5)-yl]phosphane (4-TIPiPr) as well as the phosphane oxide (4-TIPOiPr) and sulfide (4-TIPSiPr) ligands were prepared. These tris(imidazolyl) ligands act as N,N,N-tripodal chelating ligands. The solid-state structures of the manganese complexes [(2-TIPNMe)Mn(CO)(3)]-OTf and [(4-TIPSiPr)Mn(CO)(3)]OTf as well as the rhenium compound [(4-TIPOiPr)Re(CO)(3)]OTF were determined by X-ray diffraction. The potential of these complexes as photoactivatable CO-releasing molecules (CORMs) was studied with the UV/Vis spectroscopy-based myoglobin assay. Within the series of compounds prepared, the substitution pattern of the imidazolyl groups was found to significantly influence the CO-release efficiency and stoichiometry. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009).