Clegg William, Graham David V, Herd Emma, Hevia Eva, Kennedy Alan R, McCall Matthew D, Russo Luca
School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
Inorg Chem. 2009 Jun 15;48(12):5320-7. doi: 10.1021/ic900313b.
A systematic study of the interlocking co-complexation reactions between the primary lithium amide LiNHDipp (Dipp = 2,6-diisopropylphenyl) and dimethylzinc in the presence of different donor ligands is presented which concludes that the final outcome of these reactions is largely dictated by the type of structure that is formed when the donor is coordinated to the lithium amide. When chelating diamine TMEDA (N,N,N',N'-tetramethylethylenediamine) is employed [{Li(2)(NHDipp)(2)(TMEDA)}(infinity)] (1) is obtained, where Li(2)N(2) rings are connected by TMEDA bridges generating a polymeric chain arrangement which does not form a co-complex with Me(2)Zn even in the presence of an excess of TMEDA. The tridentate ligand PMDETA (N,N,N',N'',N''-pentamethyldiethylenetriamine) when reacted with LiNHDipp forms monomeric (PMDETA)Li(NHDipp) which successfully forms a mixed-metal co-complex with Me(2)Zn affording dialkyl(amido)zincate [(PMDETA)LiZn(NHDipp)(Me)(2)] (2). When the co-complexation reaction is carried out in the presence of monodentate tetrahydrofuran (THF), zincate [(THF)(3)LiZn(NHDipp)(Me)(2)] (3) is obtained which was found to partially decompose in hexane solution after long periods of time at room temperature (2 weeks) to afford the unprecedented "zinc-rich" zincate [(THF)(3)LiZn(2)(Me)(3)(NHDipp)(2)] (5). This compound presents a unique structure in the solid state previously unknown in organozincate chemistry with a trinuclear Li...Zn...Zn chain arrangement where the metals are connected by only two amido bridges and therefore both zinc centers exhibit trigonal planar geometries. 5 can be prepared in good yields by the rational reaction of LiNHDipp with a 2:1:3 mixture of Me(2)Zn, NH(2)Dipp and THF. The different solid-state structural motifs of compounds 1, 2, 4, and 5 have been revealed by X-ray crystallographic studies. Multinuclear NMR ((1)H, (13)C and (7)Li) spectroscopic data recorded in C(6)D(6) solution are also reported for compounds 1-6. Mixed-metal compounds 2 and 5 constitute the first examples of crystallographically characterized alkyl(amido)zincates containing a primary amide.
本文介绍了在不同供体配体存在下，伯胺基锂LiNHDipp（Dipp = 2,6 - 二异丙基苯基）与二甲基锌之间连锁共络合反应的系统研究，得出这些反应的最终结果很大程度上取决于供体与胺基锂配位时形成的结构类型。当使用螯合二胺TMEDA（N,N,N',N'-四甲基乙二胺）时，得到[{Li(2)(NHDipp)(2)(TMEDA)}(infinity)]（1），其中Li(2)N(2)环通过TMEDA桥连接形成聚合物链排列，即使在过量TMEDA存在下也不与Me(2)Zn形成共络合物。三齿配体PMDETA（N,N,N',N'',N''-五甲基二亚乙基三胺）与LiNHDipp反应形成单体[(PMDETA)Li(NHDipp)]（4），其成功与Me(2)Zn形成混合金属共络合物，得到二烷基（酰胺基）锌酸盐[(PMDETA)LiZn(NHDipp)(Me)(2)]（2）。当在单齿四氢呋喃（THF）存在下进行共络合反应时，得到锌酸盐[(THF)(3)LiZn(NHDipp)(Me)(2)]（3），发现在室温下（2周）长时间后，其在己烷溶液中会部分分解，得到前所未有的“富锌”锌酸盐[(THF)(3)LiZn(2)(Me)(3)(NHDipp)(2)]（5）。该化合物在固态下呈现出有机锌酸盐化学中以前未知的独特结构，具有三核Li...Zn...Zn链排列，其中金属仅通过两个酰胺桥连接，因此两个锌中心均呈现三角平面几何构型。通过LiNHDipp与Me(2)Zn、NH(2)Dipp和THF的2:1:3混合物合理反应，可高产率制备5。通过X射线晶体学研究揭示了化合物1、2、4和5不同的固态结构基序。还报道了在C(6)D(6)溶液中记录的化合物1 - 6的多核NMR（(1)H、(13)C和(7)Li）光谱数据。混合金属化合物2和5是含有伯酰胺且经晶体学表征的烷基（酰胺基）锌酸盐的首个实例。
