1,2-二(对-甲苯基)-1,2-二甲基二硅桥连二环戊二烯基四羰基二铁的合成及热重排反应

Cl2MeSiSiMeCl2与环戊二烯基锂及对甲苯基溴化镁反应, 生成C5H5(p-Tol)MeSiSiMe(p-Tol)C5H5. 后者再与五羰基铁反应, 得到标题化合物[η5, η5-C5H4(p-Tol)MeSiSiMe(p-Tol)C5H4]Fe2(CO)2(μ-CO)2(3); 同时还得到两个单硅桥连副产物[η5, η5-(p-Tol)2MeSiSiMe(C5H4)2]Fe2(CO)2(μ-CO)2(4)和[η5, η5-(p-Tol)Me2SiSiMe(C5H4)2]Fe2(CO)2(μ-CO)2(5). 化合物3中顺式异构体(3a)占绝对优势, 可通过简单重结晶分离出纯品. 化合物3a在加热条件下发生分子内的硅硅键和铁铁键之间的复分解重排反应, 生成[η5-(p-Tol)MeSiC5H4Fe(CO)2]2(6). 该产物为顺反异构体的混合物(顺反异构体的摩尔比为4:3), 表明重排反应不涉及协同历程. 利用X射线衍射法测定了化合物4的分子结构.

Synthesis and Thermal Rearrangement of 1,2-Di(p-tolyl)-1,2-dimethyldisilanylene Bridged Bis(cyclopentadienyl)tetracarbonyldiiron

Cl2MeSiSiMeCl2(1) reacted with C5H5Li and subsequently with p-tolylmagnesium bromide to afford C5H5(p-Tol)MeSiSiMe(p-Tol)C5H5(2). The latter further reacted with Fe(CO)5 gave the title complex [η5, η5-C5H4(p-Tol)MeSiSiMe(p-Tol)C5H4]Fe2(CO)2(μ-CO)2(3). Meanwhile, two mono-silicon bridged by-products [η5, η5-(p-Tol)2MeSiSiMe(C5H4)2]Fe2(CO)2(μ-CO)2(4) and [η5, η5-(p-Tol)Me2SiSiMe(C5H4)2]Fe2(CO)2(μ-CO)2(5) were also obtained. Product 3 contains predominantly the cis isomer(3a), which was isolated inpure form by simple recrystallization. Compound 3a underwent the metathesis rearrangement reaction between Si—Si and Fe—Fe bonds under thermal conditions giving complex [η5-(p-Tol)MeSiC5H4Fe(CO)2]2(6). This product was a mixture of cis and trans isomers with a molar ratio about 4:3, demonstrating that the reaction does not involve a concerted process. The molecular structure of compound 4 was determined by X-ray diffraction method.