An Unusal Case of Facile Non‐Degenerate PC Bond Making and Breaking

Oxidation of Li/X phosphinidenoid complex 2 , obtained via selective deprotonation from the P ‐H precursor 1 , with [Ph 3 C]BF 4 led to the formation of two P ‐F substituted diorganophosphane complexes 6 , 7 ; the latter tautomer 7 formed via H‐shift from 6 . In contrast, oxidation of 2 with [( p ‐Tol) 3 C]BF 4 led to three major and one minor intermediates at low temperature, which we tentatively assign to two pairs of P‐C atropisomers 10a , a′ and 10c , c′ and which differ by the relative orientations of their CH(SiMe 3 ) 2 and W(CO) 5 groups. Conversion of all isomers led finally to complex 11 having a ligand with a long PC bond to the central trityl* carbon atom, firmly established by single‐crystal X‐ray analysis. DFT calculations at the B3LYP/def2‐TZVPP//BP86/def2‐TZVP level of theory on real molecular entities revealed the structures of the in situ formed combined singlet diradicals ( 4 + 5 and 5 + 9 ) and the nature of intermediates on the way to the final product, complex 11 . Remarkable is that all isomers of 11 possess relative energies in the narrow energy regime of about 20 kcal mol −1 . A preliminary study revealed that complex 11 undergoes selective PC bond cleavage at 75 °C in toluene solution.