The synthesis and molecular structures of the crystalline 1-aza-2-phospha(V)allyllithium compounds [Li(LL′)(OEt_2)_2] and [Li(LL′)]_2[LL′=CH(SiMe_3)P(Ph)_2=NSiMe_3] and the preparation and characterisation of the new phosphinimines CH(R~1)(R~2)

摘要

Reaction of CH_2(SiMe_3)P(Ph)_2=NSiMe_3(HLL′)I with LiBu~n afforded, after recrystallisation from diethyl ether, [Li{CH(SiMe-3)P(Ph)_2=NSiMe_3}(OEt_2)_2]. Removal of the co-ordinating Et_2O molecules in vacuo and subsequent recrystallisation from hexane yielded the solvent -free dimeric lithium complex [Li{CH(SiMe_3)P(Ph)_2=NSiMe_3}]_2. The crystal structures of the crystalline compounds [Li(LL′)(OEt_2)_2] and the fused dinulear [Li(LL′)]_2 are reported. Each contains a planar Li(LL′) ring.The Li(2)-N bond of the Li(LL′) moiety of the latter is also part of a six membered Li(2)-N-Li(1)-N-P-C ring, planar except for Li(2); the two Li atoms are bridged by a second [LL′]-ligand, so that the bridgehead lithium atom Li(2) is bound to the allyl carbon of each [LL′]~- ligand, wheeas Li(1) is bound to two nitrogen atoms. In toluene-d_8, this compound shows singlet ~7Li-{~1H} and NMR spectral signals, even at low temperatures. Its reaction with Me_3SiO_3SCF_3 afforded the phosphinimine CH(SiMe_3)_2P(Ph)_2=NSiMe_3(HLL")II, a potential precursor for a new 1-aza-2-phospha(V)allyl ligands, as was shown by its straight-forward lithiation to yield Li(LL"). The novel phosphinimine CH_2{SiMe_2(NEt_2)}P(Ph)_2=NSiMe_3 (HLL~(///)) III was synthesized by reaction of Li[CH_2P(Ph)_2=NSiMe_3] with Et_2NSi(Me)_2Cl and, similar to the lithiation of II, reaction of III with LiBu~n afforded Li(LL~(///)) in high yield.