Complexes of a dianionic bis(diphosphinomethanide) with lithium, sodium, potassium and zirconium. Effect of substitution on the Schlenk dimerisation of vinylidene phosphines
Abstract
The vinylidene phosphine (Prn2P)2CCH2
(1) undergoes Schlenk dimerisation on treatment with an excess of any of the alkali metals Li, Na or K to give the butane-1,4-diide complexes [(L)M{(Prn2P)2CCH2}]2
[(L)M =
(THF)2Li (6), (THF)3Na (7b), (DME)2K (8b)], after recrystallisation. Whereas the reaction between the analogous phenyl derivative (Ph2P)2CCH2 and K results in cleavage of a P–C bond, 1 reacts smoothly with K to give 8, with no evidence for P–C cleavage. Compound 6 is an excellent