Reactivity of CO2 towards Mo[N(R)Ph]3.
The Laplaza/Cummins L(3)Mo (L = N(R)Ar) system is a very important complex for activating small molecules such as N(2). Previous experimental work has shown that CS(2) binds to the L(3)Mo system and forms an Mo-CS-Mo intermediate, while the environmentally important CO(2) molecule is unreactive. The aim of this paper is to explain why there is this contrast in reactivity. We have used density functional methods to show that at first glance the reaction of 3L(3)Mo + CO(2) should proceed smoothly to give L(3)Mo-O + L(3)Mo-CO-MoL(3). However initial coordination of the CO(2) molecule to L(3)Mo does not take place because of the bending of CO(2), the energy required to cross from the doublet to the quartet state, and the lower metal-CO(2) binding energy compared to metal-CS(2). The subsequent formation of the L(3)Mo-CO-MoL(3) intermediate is similarly unfeasible due to steric and entropic effects. We have provided a molecular orbital rationalization for these effects and have also shown that it is important to take account of steric factors in order to get an accurate understanding of the energetic picture.
Brookes
Nigel J
NJ
School of Chemistry, University of Tasmania, Private Bag 75, Hobart, Tas 7001, Australia.
Ariafard
Alireza
A
Stranger
Robert
R
Yates
Brian F
BF