ChemInform Abstract: STABLE SOLID SILAETHYLENES

Abstract

Die Photolyse der Acylsilane (I), dargestellt aus Tris‐ [trimethylsilyl]‐silyl‐Li und entsprechenden Säurechloriden, führt zu den Silaethylenen (II), deren Stabilität vom Substituenten R bestimmt wird.

1,2-Siloxetanes: formation, structure, and rearrangements.

“…Some of this crowding has been reduced by folding the ring by 20.1°about the Si(l)-C( 2) axis. This fold angle is comparable to the fold angle ( 17 2) and phenyl ring (22) toward "equatorial" positions on the ring and away from the adamantyl group while forcing the groups Me3Si( 3) and the phenyl ring (21) together on the opposite side of the siloxetane ring. This results in large differences between the Si(3,4)-Si(l)-0(1),C(1) bond angles (up to 25.8°) and differences up to 14.8°between the C(211,221)-C(2)-0- (1),C(1) angles (Table III), with the smaller angles involving the oxygen.…”

“…Furthermore, steric interactions involving the OSiMe3 group are somewhat reduced as the Si(4)-0(2)-C(l) angle [148.2 (6)°] is significantly enlarged over comparable COSi angles in the less sterically crowded com-pound 16 above [135.2 ( 6)°] and in an adamantylsilene [134.20]. 21 Notably the Si(4)-0( 2) distance [1.635 (6) Á] is slightly shorter than that in 16 [1.660 (7) Á], and this is consistent with the trend of decreasing Si-0 bond lengths with increasing Si-O-Si bond angles observed in several disiloxanes.22…”

“…In the remaining Me3Si and Ad groups evidence of the steric strain in the molecule can be seen in the substantial differences in the Si-Si-Me and C(l)-C(ll)-C(Ad) angles, although the Si-SiMe3 (and C(l)-Ad) distances appear normal and are somewhat shorter than those observed in A [2.43 Á]. Thus, the difference between largest and smallest angles is 12.0°( Si( 2)), 14.4°( Si(3)), 6.6°( Si(4)), and 5.6°( C(ll)), with the largest angles at Si(2) and Si (3) [119°] such that the interactions C( 22)-Ad and C(33)-Ph (21) are reduced (Figure 1).…”

The silicon-carbon double bond: a healthy rivalry between theory and experiment

“…The importance of 11 this achievement by Brook and coworkers has been greatly enhanced by preliminary single-crystal X-ray studies. 12 In their first communication 11 on the subject Brook, Abdesaken, Gutekunst, Gutekunst, and Kallury reported the synthesis of (7) (2) Both the infrared and ultraviolet (electronic) spectra of silaethylene were observed by Maier and coworkers, but no assignments were presented.…”

Reaktionen des Bis(tert-butyl-methyl)ketazins mit Halogensilanen

“…Versetzt man das in n-Hexan lithiierte Bis(tert-butyl-methyl)ketazin bei 0 °C mit Di- Adduktbindung zum Silicium die 29 Si-Verschiebung in Richtung Hochfeld beeinflussen. Zudem weisen auch die stabilen Silaethene von BROOK [59] und WIBERG [60] stark unterschiedliche 13 C-und 29 von WIBERG [62] isolierten Silaethen-Aminadduktes (δ 29 Arbeitskreis MELLER [9] ist bekannt, dass bei der Umsetzung von dilithiierten Ketazinen mit Trihalogenboranen ein Gemisch aus drei verschiedenen Produkten entsteht: Bei den Hydrazonen sind Umlithiierungsreaktionen im Arbeitskreis KLINGEBIEL [63,64] beschrieben worden:…”