The addition compound Cl(3)SiSiCl(3)·TMEDA was formed quantitatively by treatment of Cl(3)SiSiCl(3) with tetramethylethylenediamine (TMEDA) in pentane at room temperature. The crystal structure of Cl(3)SiSiCl(3)·TMEDA displays one tetrahedrally and one octahedrally bonded Si atom (monoclinic, P2(1)/n). (29)Si CP/MAS NMR spectroscopy confirms this structure. Density functional theory (DFT) calculations have shown that the structure of the meridional isomer of Cl(3)SiSiCl(3)·TMEDA is 6.3 kcal lower in energy than that of facial coordinate species. Dissolving of Cl(3)SiSiCl(3)·TMEDA in CH(2)Cl(2) resulted in an immediate reaction by which oligochlorosilanes Si(n)Cl(2n) (n = 4, 6, 8, 10; precipitate) and the Cl(-)-complexed dianions [Si(n)Cl(2n+2)](2-) (n = 6, 8, 10, 12; CH(2)Cl(2) extract) were formed. The constitutions of these compounds were confirmed by MALDI mass spectrometry. Additionally, single crystals of [Me(3)NCH(2)CH(2)NMe(2)](2)[Si(6)Cl(14)] and [Me(3)NCH(2)CH(2)NMe(2)](2)[Si(8)Cl(18)] were obtained from the CH(2)Cl(2) extract. We found that Cl(3)SiSiCl(3)·TMEDA reacts with MeCl, forming MeSiCl(3) and the products that had been formed in the reaction of Cl(3)SiSiCl(3)·TMEDA with CH(2)Cl(2). X-ray structure analysis indicates that the structures of [Me(3)NCH(2)CH(2)NMe(2)](2)[Si(6)Cl(14)] (monoclinic, P2(1)/n) and [Me(3)NCH(2)CH(2)NMe(2)](2)[Si(8)Cl(18)] (monoclinic, P2(1)/n) contain dianions adopting an "inverse sandwich" structure with inverse polarity and [Me(3)NCH(2)CH(2)NMe(2)](+) as countercations. Single crystals of SiCl(4)·TMEDA (monoclinic, Cc) could be isolated by thermolysis reaction of Cl(3)SiSiCl(3)·TMEDA (50 °C) in tetrahydrofuran (THF).
A one-pot synthesis of the tetrasilatetrahedrane (tBu 3 Si) 4 Si 4 was achieved by the reaction of HSiCl 3 and Na[SitBu 3 ]. In this reaction the silane tBu 3 SiH was obtained along with (tBu 3 Si) 4 Si 4 and tBu 3 SiSitBu 3 . The tetrasilatetrahedrane (tBu 3 Si) 4 Si 4 was also obtained via a one-pot approach by treatment of Cl 3 SiSiCl 3 or Cl 3 SiSiCl 2 SiCl 3 with Na-[SitBu 3 ]. In the reaction of HSiCl 3 with Na[SitBu 3 ], two molecules of the tetrasilatetrahedrane (tBu 3 Si) 4 Si 4 crystallize together with one molecule of tBu 3 SiSitBu 3 and one molecule of benzene. Single crystals suitable for X-ray diffraction composed of one molecule of (tBu 3 Si) 4 Si 4 and two molecules of benzene were obtained by recrystallization from benzene.
Unexpected Disproportionation of Tetramethylethylenediamine-Supported Perchlorodisilane Cl3SiSiCl3. -Reactions of (I) with tetramethylethylenediamine are studied and the crystal structures of (II), (III), (IV), and (VI) are determined by single crystal XRD. Compounds (II) and (IV) crystallize in the monoclinic space group P21/n with Z = 4, (III) in the monoclinic space group P21/n with Z = 2, and (VI) in the monoclinic space group Cc with Z = 16. The crystal structure of (II) displays one tetrahedrally and one octahedrally bonded Si atom. -(TILLMANN, J.; MEYER-WEGNER, F.; NADJ, A.; BECKER-BALDUS, J.; SINKE, T.; BOLTE, M.; HOLTHAUSEN, M. C.; WAGNER, M.; LERNER*, H.-W.; Inorg. Chem. 51 (2012) 15, 8599-8606, http://dx.
We present here the crystal structures of two acetylene derivatives cocrystallized with benzene, namely bis(trimethylsilyl)acetylene benzene solvate, C(8)H(18)Si(2).C(6)H(6), (I), and diphenylacetylene benzene solvate, C(14)H(10).C(6)H(6), (II). In (I), both molecules belong to the symmetry point group C(2h) and are located about special positions with site symmetry 2/m. In (II), both molecules show crystallographic inversion symmetry. In both structures, there are C-H...pi contacts between aromatic H atoms and the pi-electrons of the triple bond. In addition to these, in (II) there are C-H...pi contacts between aromatic H atoms and the pi-electron cloud of the benzene molecules.
The reaction of 4-chloro-1,2-dimethyl-4-supersilylsila-1-cyclopentene (2 a) with Li[NiPr2] at -78 °C results in the formation of the formal 1,4-addition product of the silacyclopentadiene derivative 3,4-dimethyl-1-supersilylsila-1,3-cyclopentadiene (4 a) with 2,3-dimethyl-4-supersilylsila-1,3-cyclopentadiene (5 a). In addition the respective adducts of the Diels-Alder reactions of 4 a+4 a and 4 a+5 a were obtained. Compound 4 a, which displays an s-cis-silacyclopentadiene configuration, reacts with cyclohexene to form the racemate of the [4+2] cycloadduct of 4 a and cyclohexene (9). In the reaction between 4 a and 2,3-dimethylbutadiene, however, 4 a acted as silene as well as silacyclopentadiene to yield the [2+4] and [4+2] cycloadducts 10 and 11, respectively. The constitutions of 9, 10, and 11 were confirmed by NMR spectroscopy and their crystal structures were determined. Reaction of 4-chloro-1,2-dimethyl-4-tert-butyl-4-silacyclopent-1-ene (2 c) with KC8 yielded the corresponding disilane (12), which was characterized by X-ray crystal structure analysis (triclinic, P1). DFT calculations are used to unveil the mechanistic scenario underlying the observed reactivity.
Molecules of the title compound, [HgBr(C9H11)], are located on a crystallographic twofold rotation axis. Due to the molecular symmetry, the HgII atom is linearly coordinated by the ipso-C of the mesityl group and the Br atom. In the crystal, molecules lie in planes parallel to (001).
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