1,4‐Di‐tert‐butyl‐2,6‐bis(trimethylsilyl)silabenzene, the First Silabenzene Stable in Solution at −100°C

Abstract

Bulky substituents do not always provide for a kinetic stabilization. Otherwise one could not explain the fact that the title compound 2 is stable only below −100°C. 2 can be generated by photochemical cleavage of N2 from 1 in a Trapp mixture at −110°C and characterized spectroscopically. 2 reacts with methanol to give the adduct 3.

Synthesis and Properties of an Overcrowded Silabenzene Stable at Ambient Temperature

“…Furthermore, measurement of 29 Si NMR in THF/C 6 D 6 (6/1) induced no significant change of the chemical shift (d 93.4), suggesting that 1 is not coordinated by THF. These stabilities of 1 are clearly different from those Märkl [4] previously reported for 2,6-bis(trimethylsilyl)-1,4-di-tert-butylsilabenzene, demonstrating the excellent steric protection afforded by the Tbt group. Unfortunately, isolation of 1 has not been achieved yet since separation of the mixture of 1 and 10 requires exposure to air.…”

“…[4] We report here a new dimension of this application, that is, an intermolecular Pauson ± Khand reaction in supercritical ethylene. Ethylene is one of the most abundant raw materials in the petrochemical industry.…”

“…[2] Although aromatic character of silabenzene has been theoretically predicted and some silabenzenes were observed spectroscopically in the gas phase and in low-temperature matrices, [3] their high reactivity prevented the syntheses of silabenzenes as stable molecules. Märkl et al [4] previously reported the synthesis of 2,6-bis(trimethylsilyl)-1,4-di-tert-butylsilabenzene, but it was reported as stable only below À 100 8C in solution (THF/Et 2 O/petroleum ether, 4/1/1) and, judging from its relatively high field 29 Si NMR chemical shift (d 26.8), stabilized by the coordination of a Lewis-base solvent (see below). In contrast, we have recently succeeded in the synthesis of the first stable silabenzenoid compound, 2-silanaphthalene, [5] by protecting its reactive silicon center with an extremely bulky substituent group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (ªTbtº).…”

Heteroatom chemistry in Asia: Past, present, and future

“…After the attempted synthesis of a silabenzene by Märkel et al [40], Tokitoh and Okazaki et al opened the chemistry of neutral aromatic compounds containing heavier group 14 elements. As the first example, 2-silanaphthalene 28 (Scheme 10) was synthesized by taking advantage of kinetic stabilization by the Tbt group [41].…”

Heavy Analogs of Aromatic Compounds

“…25 The transient 9-silaanthracene derivatives 9 were also stabilized and directly detected in an argon matrix at low temperatures by UV and fluorescence spectroscopy, and in the gas phase of a mass spectrometer by the neutralizationreionization mass spectrometry technique. 27 In the absence of trapping reagents, 4d was stable in solution up to ca. 27 In the absence of trapping reagents, 4d was stable in solution up to ca.…”