Interpretation of Tolman electronic parameters in the light of natural orbitals for chemical valence.
Understanding the nature and the strength of metal-ligand interactions in d- and f-block metal complexes has always been a central issue for both synthetic and theoretical chemists. These interactions are usually described according to the well accepted Dewar-Chatt-Duncanson model, and thus over the years numerous research groups directed their efforts to shed light on the role of σ- and π-contributions. Among others, the electronic parameter introduced by Tolman in the 1970s represents a milestone in this field. Herein we present a quantitative description of the nickel-phosphine bond in Tolman's nickel(0) carbonyl complexes. The combination of Natural Orbitals for Chemical Valence with Energy Decomposition Analysis resulted in the definition of a new parameter (Tphos) which comprises all the energetic contributions needed to describe the nickel-phosphine bond and thus stands as a reliable descriptor of the electronic properties of phosphines. Moreover, steric effects of phosphines (i.e. Tolman's cone angles) have been considered too, and a linear relation including Ni-P bond distances, Tphosand cone angle has been found.
Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell'Insubria, Via Valleggio, 9, 22100 Como, Italy. stefano.brenna@uninsubria.it.
G Attilio
http://orcid.org/0000-0002-7427-9919
GA
Ardizzoia
Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell'Insubria, Via Valleggio, 9, 22100 Como, Italy. stefano.brenna@uninsubria.it.
Stefano
http://orcid.org/0000-0002-2873-2436
S
Brenna