Nature of the bonding in a carbene-phosphinidene: A main group analogue of a Fischer carbene complex? Isolation and characterisation of a bis(borane) adduct

The reaction of the carbene-phosphinidene (1,3-dimesitylimidazolin-2-ylidene)PPh 1 with BH3 . thf affords the corresponding P-bonded bis(borane) adduct, thus demonstrating the availability of two lone pairs on the phosphorus centre; base competition studies reveal that 1 is a strong phosphorus base and, by means of cyclic voltammetry, it is established that 1 undergoes facile oxidation.