SYNTHETIC, STRUCTURAL, MECHANISTIC, AND THEORETICAL MO STUDIES OF THE ALKALI-METAL CHEMISTRY OF DIBENZYLAMINE AND ITS TRANSFORMATION TO 1,3-DIPHENYL-2-AZAALLYL DERIVATIVES

被引:60
作者
ANDREWS, PC
ARMSTRONG, DR
BAKER, DR
MULVEY, RE
CLEGG, W
HORSBURGH, L
ONEIL, PA
REED, D
机构
[1] UNIV STRATHCLYDE,DEPT PURE & APPL CHEM,GLASGOW G1 1XL,LANARK,SCOTLAND
[2] UNIV NEWCASTLE UPON TYNE,DEPT CHEM,NEWCASTLE TYNE NE1 7RU,TYNE & WEAR,ENGLAND
[3] UNIV EDINBURGH,EDINBURGH EH9 3JJ,MIDLOTHIAN,SCOTLAND
关键词
D O I
10.1021/om00001a059
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
Dibenzylamido anions ((PhCH(2)N-) can be transformed into 1,3-diphenyl-2-azaallyl anions ({PhC(H)-N-C(H>Ph}(-)) by the assistance of PMDETA- ((Me(2)NCH(2)CH(2))(2)NMe) complexed Li+, Na+, or K+ cations. The heavier alkali-metal cations give only the trans,trans conformation of the azaallyl anion, in contrast to the lighter Li+ cation, which yields two crystalline conformers, the trans,trans and an unknown species, Ab initio MO geometry optimizations on model Li and Na complexes intimate that it is the relative tightness of the contact ion pair structures which dictates this distinction with Li+ having more influence on the conformation and stability of the anion than Na+, which forms a much looser contact ion pair more akin to the ''free'' anion, On the basis of kinetic H-1 NMR studies, combined with X-ray crystallographic data, the amido --> azaallyl conversion can be explained in terms of a two-step process involving beta-elimiqation of a metal hydride followed by hydride metalation of the produced imine PhCH(2)N=C(H)Ph. This process appears to be initiated by deaggregation of the metallodibenzylamine to an intermediate monomeric structure, accomplished by solvation. The nature and degree of solvation required depend on the particular M(+) cation involved. Three new crystal structures are revealed in the course of this study. All are based on familiar four-membered (N-M)(2) rings, but whereas the sodium complex [{(PhCH(2))(2)NNa.TMEDA}(2)] and the lithium complex [{(PhCH(2))(2)NLi.THF}(2)] are both discrete dimers, unique [{[(PhCH(2))(2)NLi](2).(dioxane)}infinity], isolated as its toluene hemisolvate, is a polymer composed of linked dimeric units and so is the first dibenzylamido alkali-metal species to have an infinitely extended structure.
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页码:427 / 439
页数:13
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