Unsaturated compounds of silicon and group homologues

9.1 – Organosilanes

Reaction of the bulkily substituted dichlorodiorganosilanes R1R2SiCl2 (R1 = Mesityl, R2 = Mesityl, tBu, OtBu, Xylyl, iBu) with LiPH2. dme in a 1 : 2 molar ratio in THF at -30°C leads to the new organo-substituted 1,3,2,4-diphosphadisiletanes 1a—e. Compounds 1c—e are isolated as mixtures of diastereomers. The crowded dichlorosilane Is(tBu)SiCl2 (Is = 2,4,6- triisopropylphenyl) reacts with LiPH2. dme above 10°C to yield the disubstituted products Is(tBu)Si(PH2)2 (2f) in 87% yield and only minor amounts of the corresponding four-membered ring [Is(tBu)SiPH]2 (1f), detected by 31P- and 29Si-NMR spectroscopy. Treatment of 2f with 2 equivalents of nBuLi in Et2O gives Is(tBu)Si(PHLi)2 (3f), which with Is(tBu)SiCl2 forms 1f. The reaction of difluorodiisitylsilane with LiPH2.dme in THF leads to different products, depending on the reaction temperature. At — 30°C Is2Si(PHLi)F (7g) is obtained as sole product, whereas at 28°C the air-stable diphosphino-substituted Is2Si(PH2)2 (2g) is formed. Elimination of LiF from 7g affords the tetraisityl-substituted P2Si2-cyclobutane 1g, and treatment with H2O and Me3SiCl leads to Is2Si(PH2)F (8g) and Is2Si(PHSiMe3)F (9g). The temperature-dependent 1H-NMR spectra of 1a — g exhibit two dynamic processes: hindered rotation of the aryl groups at silicon and inversion at phosphorus. — The solid state structures of 1a, 1b, 1g, and 2g are established by X-ray crystallography. Reaction of 1a with 2 equivalents of M(CO)5.thf (M = Cr, W) yields the P,P′-bis(pentacarbonylmetal) complexes 10a (M = Cr) and 11a (M = W). A single-crystal X-ray diffraction analysis of 10a is performed.



Concerning New 1,3,2,4-Diphosphadisiletanes and Diorganodi(phosphino)silane Derivatives

Zur Kenntnis neuer 1,3,2,4‐Diphosphadisiletan‐ und Diorganodi(phosphino)silan‐Derivate

Si based sheets have attracted tremendous attention due to their compatibility with the well-developed Si-based semiconductor industry. On the basis of state-of-the-art theoretical calculations, we systematically study the stability, electronic and optical properties of Si based porous sheets including g-Si4N3, g-Si3N4, g-Si3N3 and g-Si3P3. We find that the g-Si3N3 and g-Si3P3 sheets are thermally stable, while the g-Si4N3 and g-Si3N4 are unstable. Different from the silicene-like sheets of SiN and Si3N which are nonplanar and metallic, both the porous g-Si3N3 and g-Si3P3 sheets are planar and nonmetallic, and the former is an indirect band gap semiconductor with a band gap of 3.50 eV, while the latter is a direct band gap semiconductor with a gap of 1.93 eV. Analysis of the optical absorption spectrum reveals that the g-Si3P3 sheet may have applications in solar absorbers owing to its narrow direct band gap and wide range optical absorption in the visible light spectrum.

Electronic and optical properties of silicon based porous sheets

Synthesis and hydrolysis of a fluorosilyl-t-butylaminodichloroalane. Crystal structures of the cyclic compounds [(Me3SiNMe)2SiNCMe3]2 and (Me3CNHAlCl2)2

Lithio-aminofluorsilane werden in der Reaktion von Aminofluorsilanen mit Butyllithium erhalten. Die thermische LiF-Abspaltung aus Lithio-aminofluorsilanen ist ein einfacher Syntheseweg fur viergliedrige Silicium-Stickstoff-Ringe. Rontgenstrukturuntersuchungen wurden von 1,3-Bis(3,5-dimethylphenyl)-2,2,4,4-tetramethyl-1,3-diaza-2,4-disilacyclobutan und von 2,4-Di-tert.-butyl-2,4-difluor-1,3-bis(2,4,6-trimethylphenyl)-1,3-diaza-2,4-disiacyclobutan durchgefuhrt.

Darstellung und Molekülstruktur von 1,3-Diaza-2,4-disilacyclobutanen

Fluorosilylphosphanes of the type R2SiFPHR′ (R = CHMe2, CMe3, NMeSiMe3; R′ = H, C6H5; 1-4) are obtained in the reaction of difluorosilanes with lithiated phosphanes in a molar ratio 1:1. Diphosphasilanes (5, 6) and a difluorosilylphosphane (7) are isolated as by-products. 1-4 react with n-C4H9Li to give cyclic silylphosphanes, LiF, and C4H10 (8-11). Dilithiated 5 reacts with F2PN(CMe3)SiMe3 to form of a four-membered SiP3-ring 12. The 31P NMR spectra of 9 and 11 show signal coalescence for the cis-and trans-isomers at room temperature. The crystal structure of the cis-isomer of 11 has been determined. The substituted ring 13 is prepared in the reaction of lithiated 9 and Me2SiF2

Synthese von Silicium-Phosphor-Ringen: Struktur eines cis-2.2.4.4-Tetrakis(silylamino)-1.3-diphospha-2.4-disilacyclobutans

2,4,6-Trifluoro-1,3,5-trimethyl-2,4,6-triphenylcyclotrisilazane

http://journals.iucr.org/b/issues/1981/04/00/a20072/a20072.pdf

Difluorosilanediyl-1,1'-bis(2,2,4,4,6,6-hexamethylcyclotrisilazane)

http://journals.iucr.org/c/issues/1984/05/00/a23611/a23611.pdf

N. Vater

Papers

Darstellung und Molekülstruktur von 1,3-Diaza-2,4-disilacyclobutanen

Synthese von Silicium-Phosphor-Ringen: Struktur eines cis-2.2.4.4-Tetrakis(silylamino)-1.3-diphospha-2.4-disilacyclobutans

2,4,6-Trifluoro-1,3,5-trimethyl-2,4,6-triphenylcyclotrisilazane

Difluorosilanediyl-1,1'-bis(2,2,4,4,6,6-hexamethylcyclotrisilazane)

Structure of 1,3‐di‐tert‐butyl‐2,2,4,4‐tetraisopropylcyclodisilazane, C20H46N2Si2