Electronegativity and chemical hardness of organoelement groups

The experimental approaches to estimation of comparative electronegativity and chemical hardness of organometallic groups have been proposed. Qualitative data on the electronegativity of L nM groups were obtained from 19F NMR study of model systems 4-FC6H4QMLn (Q = CC, N(R), O, C(O)O, S), (4-FC6H4)3 SnML n and (4-FC6H4)3SnQML n (Q = O, S), containing a great variety of different organometallic groups containing transition or heavy main-group metals. The data on chemical hardness of L nM groups were obtained from NMR study of distribution of different L nM groups between hard and soft anions. The following basic results have been obtained. (1) The relative electronegativity and chemical hardness of L nM groups can change in parallel or not with the electronegativity and hardness of the central metal atom. (2) The substituents in Ar can substantially modify electronegativity and hardness of Ar nM groups; the influence of Ar groups has an inductive nature; the increase in electron-donating ability of aryl ligands enhances the hardness of Ar nM cations. (3) The relative electronegativity and hardness of L nM groups in L nMX are invariant and do not depend on X.