Ligand dissociation accelerated by spin state change: locating the minimum energy crossing point for phosphine exchange in CpMoCl2(PR3)2 complexes

The minimum energy crossing point between the doublet and quartet potential energy surfaces of CpMoCl2(PH3)2 is calculated to lie 4.8 kcal mol−1 lower in energy than the doublet dissociative intermediate CpMoCl2(PH3). Implications for the influence of spin state changes on the rates of organometallic reactions are discussed.