Transition-metal binding sites and ligand parameters

A scale of ligand constants, PL, is defined according to equation (1). This scale is used to analyse the E½ox of PL=E½ox[Cr(CO)5L]–E½ox[Cr(CO)6](1) various closed-shell octahedral complexes [M3L], in terms of the linear approximation of equation (2), where Es is a E½ox[MsL]=Es+β. PL(2) measure of the electron-richness of the site Ms and β a measure of its polarisability. Other properties of [MsL] such as the type of ligand which binds to Ms, spectroscopic properties, and chemical reactivity are discussed in terms of the parameters PL, Es, and β. It is shown that equation (2) can be used in the identification of unknown [MsL] and conversely in the design of electron-rich or -poor [MsL].