Koch Alexander, Görls Helmar, Krieck Sven, Westerhausen Matthias
Friedrich Schiller University Jena, Institute of Inorganic and Analytical Chemistry, Humboldtstrasse 8, D-07743 Jena, Germany.
Dalton Trans. 2017 Jul 18;46(28):9058-9067. doi: 10.1039/c7dt01538k.
Lithiation of HN(SiMe) in hexane and crystallization in the presence of 2,2,5,5-tetramethyltetrahydrofuran (MeTHF) allows the isolation of crystalline tetrameric [LiN(SiMe)] (1) with an average Li-N distance of 208.9 pm. Deprotonation of a methylene-bridged bis(imidazolium) diiodide with NaN(SiMe) in tetrahydrofuran (THF) yields 1,1'-diisopropyl-3,3'-methylene-diimidazole-2,2'-diylidene (HC(NHC)) and layering of this orange reaction mixture with pentane yield [{HC(NHC)}{(thf)NaI}] (2). The reaction of this bis(imidazolium) diiodide with excess of KN(SiMe) in THF leads to the formation of [{HC(NHC)}KN(SiMe)] (3). Due to the fact that 2 and 3 are polymeric in the crystalline state, the bulkier 1,1'-bis(2,6-diisopropylphenyl)-3,3'-methylene-diimidazole-2,2'-diylidene (HC(NHC)) has been used. Thus, addition of HC(NHC) with the bulky 2,6-diisopropylphenyl (Dipp) groups to AN(SiMe) (A = Li, Na, K) in toluene yields mononuclear [{HC(NHC)}LiN(SiMe)] (4) and dinuclear [{HC(NHC)}AN(SiMe)] for sodium (5) and potassium (6). The rather short alkali metal-carbon bonds lie in the range of alkylmetal derivatives.
在己烷中对HN(SiMe)进行锂化，并在2,2,5,5-四甲基四氢呋喃（MeTHF）存在下结晶，可以分离出平均Li-N距离为208.9 pm的结晶四聚体[LiN(SiMe)]（1）。在四氢呋喃（THF）中用NaN(SiMe)使亚甲基桥连的双（咪唑鎓）二碘化物去质子化，得到1,1'-二异丙基-3,3'-亚甲基-二咪唑-2,2'-二亚基（HC(NHC)），将该橙色反应混合物与戊烷分层得到[{HC(NHC)}{(thf)NaI}]（2）。该双（咪唑鎓）二碘化物在THF中与过量的KN(SiMe)反应导致形成[{HC(NHC)}KN(SiMe)]（3）。由于2和3在结晶状态下是聚合物，因此使用了体积更大的1,1'-双（2,6-二异丙基苯基）-3,3'-亚甲基-二咪唑-2,2'-二亚基（HC(NHC)）。因此，在甲苯中将带有庞大的2,6-二异丙基苯基（Dipp）基团的HC(NHC)添加到AN(SiMe)（A = Li、Na、K）中，得到单核[{HC(NHC)}LiN(SiMe)]（4）以及钠（5）和钾（6）的双核[{HC(NHC)}AN(SiMe)]。相当短的碱金属-碳键处于烷基金属衍生物的范围内。
