Application of the E-C approach to understanding the bond energies thermodynamics of late-metal amido, aryloxo and alkoxo complexes: an alternative to p pi/d pi repulsion
Pl. Holland et al., Application of the E-C approach to understanding the bond energies thermodynamics of late-metal amido, aryloxo and alkoxo complexes: an alternative to p pi/d pi repulsion, COMM INOR C, 21(1-3), 1999, pp. 115-129
The concept of p pi/d pi repulsion in alkoxo and amido complexes of the lat
e transition metals has been critically examined, especially as it relates
to recent work by the authors on a series of nickel complexes, The thermody
namic preferences of late-metal M-X bonds (X = NR2, OR) can be explained by
an alternative model which uses bond polarity as a starting point and E-C
theory for quantification, In this model, the greater electrostatic charact
er of the M-X bond (relative to the H-X bond) is sufficient to explain obse
rved thermodynamic trends in ligand exchange reactions, without the inclusi
on of pi-effects. The implications of adopting the polar bonding model have
been examined, including discussion of metal alkyl complexes as well as ox
o and imido complexes. In general, this polar model appears to lead to grea
ter consistency with observation and deeper understanding, although more da
ta are necessary to clearly determine the best way of describing bonds betw
een late metals and X ligands.