Takanashi Kazunori, Lee Vladimir Ya, Matsuno Tadahiro, Ichinohe Masaaki, Sekiguchi Akira
Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
J Am Chem Soc. 2005 Apr 27;127(16):5768-9. doi: 10.1021/ja050938y.
The anionic complex of [tetrakis(di-tert-butylmethylsilyl) tetrasilacyclobutadiene]dicarbonylcobalt, [(R4Si4)Co(CO)2]-.K+ (R = SiMetBu2) 2-.K+, was synthesized by the reaction of tetrasilacyclobutadiene dianion dipotassium salt [R4Si4]2-.2K+ 1 with an excess of CpCo(CO)2 in THF. X-ray analysis of 2-.[K+(diglyme)2(THF)] showed an almost planar Si4 ring of rectangular shape with an in-plane arrangement of the silyl substituents. 2- was also prepared as a free anion with the [K+[2.2.2]cryptand] counterion by complexation with [2.2.2]cryptand and as a dimer {2-.[K+(THF)3]}2 without complexing reagents in THF. Such a tetrasilacyclobutadiene fragment represents a new type of ligand for Co complexes, being the first example of a cyclobutadiene containing only heavier group 14 elements.
通过四硅环丁二烯二价阴离子二钾盐[R₄Si₄]²⁻·2K⁺ 1与过量的环戊二烯基二羰基钴CpCo(CO)₂在四氢呋喃（THF）中反应，合成了[四（二叔丁基甲基硅基）四硅环丁二烯]二羰基钴的阴离子配合物[(R₄Si₄)Co(CO)₂]⁻·K⁺（R = SiMetBu₂）2⁻·K⁺。对2⁻·[K⁺(二甘醇二甲醚)₂(THF)]的X射线分析表明，Si₄环几乎呈平面矩形，硅基取代基呈面内排列。2⁻也可通过与[2.2.2]穴醚络合制备为带有[K⁺[2.2.2]穴醚]抗衡离子的游离阴离子，并且在四氢呋喃中不使用络合试剂时可制备为二聚体{2⁻·[K⁺(THF)₃]}₂。这样的四硅环丁二烯片段代表了一种新型的钴配合物配体，是仅含有较重14族元素的环丁二烯的首个实例。
