Unusual Solvent-Promoted Smiles Rearrangement of Two Different Phosphorus-Containing Organolithium Compounds to the Same Lithium Phosphide. Crystal Structure of MeP{C6H4-2-CH(C6H4-2-CH2NMe2)NMe2}Li(THF)2

Treatment of the tertiary phosphines RP(C 6 H 4 -2-CH 2 NMe 2 ) 2 (R = Me, 1; R = i -Pr, 4 ) with n -BuLi in THF yields the lithium phosphides [RP{C 6 H 4 -2-CH(C 6 H 4 -2-CH 2 NMe 2 )NMe 2 }]Li(THF) 2 (R = Me, 5; R = i -Pr, 6 ) as the sole phosphorus-containing products. Compound 5 is also obtained when either the lithium phosphinomethanide Li{CH 2 P(C 6 H 4 -2-CH 2 NMe 2 ) 2 } ( 3 ) or the benzyllithium complex [MeP(C 6 H 4 -2-CH 2 NMe 2 ){C 6 H 4 -2-CH(Li)NMe 2 }] 2 ( 2 ) is dissolved in THF. Conversion of 2 to 5 is extremely rapid, whereas conversion of 3 to 5 takes several days at room temperature. The deuterium-labeled compound Li{CH 2 P(C 6 H 4 -2-CD 2 NMe 2 ) 2 } ( 3a ) isomerizes in THF to DCH 2 P(C 6 H 4 -2-CD(C 6 H 4 -2-CD 2 NMe 2 )NMe 2 }Li(THF) 2 ( 5a ) and shows a strong kinetic isotope effect in comparison to the isomerization of 3 . Compounds 5 and 6 have been characterized by multinuclear NMR spectroscopy and X-ray crystallography, and a mechanism for their formation from 1 − 4 is proposed.