Principal properties of monodentate phosphorus ligands. predictive model for the carbonyl absorption frequencies in Ni(CO)3L complexes

Abstract

By use of the principal component analysis method, the principal properties of 45 different monodentate phosphorus ligands, each described by fifteen molecular descriptors, have been calculated. A principal component model composed of five principal components was determined according to cross-validation and accounted for 90% of the variance in the original data table. This model divided the P ligands into two classes, a small one which contained six polyhalogenated P ligands, and another which contained 39 different P ligands. Another principal component analysis was carried out on the large class of P ligands. This model described 90.5% of the total variance by using four principal components. Among these a subset of compounds were used for validating the relevance of the molecular descriptor variables. Two experimentally measured IR-frequencies, the carbonyl frequencies vA1 and VE were used as independent variables and correlated to the molecular descriptors using the partial least-squares regression (PLSR) method. The PLSR models showed that the calculated molecular descriptors contained relevant information concerning the investigated compounds to be used for deriving the principal properties of the monodentate phosphorus ligands. The PLSR models for the two different IR frequencies were used to predict the CO frequencies for P ligands where the IR frequencies have not been reported in the literature. © Acta Chemica Scandinavica 1997.