作者:Constantin Sicking、Andreas Mix、Beate Neumann、Hans-Georg Stammler、Norbert W. Mitzel
DOI:10.1039/c1dt10943j
日期:——
The structure of 1,3,5-trimethyl-1,3,5-triaza-cyclohexane (TMTAC) was determined by single crystal X-ray diffraction and compared with earlier gas-phase data. It shows a preference for an aee-conformation in all phases. Lithiated TMTAC, [(RLi)2·(RH)] (1) (R = 2,4,6-trimethyl-2,4,6-triaza-cyclohex-1-yl), was reacted with Et3SiCl, Ph3SiCl and PhMe2SiCl to afford the substituted silanes Et3SiR (1), Ph3SiR (2) and PhMe2SiR (3) in moderate yields. They were characterised by NMR spectroscopy (1H, 13C, 29Si). 1 reacts with Me2SiCl2 and Ph2SiCl2 to give Me2SiR2 (5) and Ph2SiR2 (6) which were characterised by NMR spectroscopy. 5 was also identified by crystal structure determination. Analogous triple substitution could not be observed by employing trichlorosilanes. Quantumchemical calculations explain this by sterical overcrowding of the silicon atom. The reaction of 1 with SiCl4 did not yield fourfold substitution but a formal insertion product of SiCl2 into a C–N bond of the TMTAC ring (2,4,6-trimethyl-2,4,6-triaza-1,1-dichloro-1-sila-cycloheptane, 7) in very small quantities. It was identified by X-ray crystallography and shows an intramolecular Si⋯N dative bond. The reactions of (3) and (5) with n-butyl lithium afforded lithiation of the silicon bound methyl groups in both cases. The products, 8 and 9, were characterised by NMR spectroscopy (1H, 13C, 29Si), 8 was also characterised by X-ray crystallography.
通过单晶X射线衍射确定了1,3,5-三甲基-1,3,5-三氮杂环己烷(TMTAC)的结构,并与早期的气相数据进行了比较。它在所有相态中都倾向于aee-构象。锂化的TMTAC,[(RLi)2·(RH)](1)(R = 2,4,6-三甲基-2,4,6-三氮杂环己-1-基),与Et3SiCl、Ph3SiCl和PhMe2SiCl反应,以中等产率得到了取代硅烷Et3SiR(1)、Ph3SiR(2)和PhMe2SiR(3)。它们通过NMR光谱(1H,13C,29Si)进行了表征。1与Me2SiCl2和Ph2SiCl2反应,得到Me2SiR2(5)和Ph2SiR2(6),这些产物通过NMR光谱进行了表征。5还通过晶体结构确定进行了鉴定。使用三氯硅烷无法观察到类似的三分取代。量子化学计算解释这是由于硅原子的空间拥挤。1与SiCl4的反应没有产生四重取代,而是以极少量形成了一个形式上的插入产物,即将SiCl2插入到TMTAC环的C-N键中(2,4,6-三甲基-2,4,6-三氮杂-1,1-二氯-1-硅杂环庚烷,7)。它通过X射线结晶学进行了鉴定,并显示出分子内Si⋯N键的配位作用。3和5与n-丁基锂的反应在两种情况下都使硅键合的甲基团锂化。产物8和9通过NMR光谱(1H,13C,29Si)进行了表征,8还通过X射线结晶学进行了表征。