Computational study of the double C–Cl bond activation of dichloromethane and phosphine alkylation at [CoCl(PR3)3]

Andrés G. Algarra, Pierre Braunstein*, Stuart A. Macgregor

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Density functional theory calculations have been employed to model the double C–Cl bond activation of CH2Cl2 at [CoCl(PR3)3] to give [CoCl3(CH2PR3)(PR3)2]. Calculations incorporating dichloromethane solution (PCM approach) on a [CoCl(PMe3)3] model system showed the two C–Cl cleavage steps to involve different mechanisms. The first C–Cl cleavage step occurs on the triplet surface and proceeds via Cl abstraction with a barrier of 19.1 kcal mol−1. Radical recombination would then give singlet mer, trans-[CoCl2(CH2Cl)(PMe3)3] with an overall free energy change of +1.8 kcal mol−1. Alternative C–Cl activation processes based on nucleophilic attack by the Co centre at dichloromethane with loss of Cl have significantly higher barriers. The second C–Cl cleavage occurs via nucleophilic attack of PMe3 at the CH2Cl ligand with formation of a new P–C bond and displacement of Cl. This may either occur in an intermolecular fashion (after prior PMe3 dissociation) or intramolecularly. Both processes have similar barriers of ca. 12 kcal mol−1. The comproportionation of [CoCl3(CH2PMe3)(PMe3)2] with [CoCl(PMe3)3] to give [CoCl2(CH2PMe3)(PMe3)], [CoCl2(PMe3)2] and 2 PMe3 is computed to be strongly exergonic, consistent with the observation of this process in analogous experimental systems.

Original languageEnglish
Pages (from-to)4208-4217
Number of pages10
JournalJournal of the Chemical Society. Dalton Transactions
Issue number12
Publication statusPublished - 26 Feb 2013


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