Coordinating ability of anions and solvents towards transition metals and lanthanides.

A scale that attempts to quantify the weakly coordinating character of a variety of solvents and anions is presented. For each group (solvent or anion), a coordinating ability index has been calculated, based on the probability of it being coordinated in the presence of a transition metal atom, compared to the probability of finding it as a solvation molecule or as non-coordinating counterion in a crystal structure. The corresponding index is also defined for the same groups in the presence of lanthanides, and the similarities and differences are discussed.