Planar Silicon and Germanium Heterocyclotriynes and Their Isomorphous Nickel(0) Complexes

Abstract

The syntheses of three strained silicon or germanium heterocyclotriynes, from the dilithium dianion of 2,2‘-diethynyltolane (Li2(OBET)) and the dialkyldichlorosilanes or dialkyldichlorogermane, are described. Reactions of the heterocyclynes with Ni(COD)2 give the nickel(0) complexes in very high yield. The heterocyclynes and their nickel complexes have been characterized by a variety of spectral techniques, and the X-ray crystal structures of compounds Si(i-Pr)2(OBET), Ni[Si(i-Pr)2(OBET)], SiPh2(OBET), Ni[SiPh2(OBET)], GePh2(OBET), and Ni[GePh2(OBET)] are reported. The heterocyclynes and their nickel complexes possess isomorphous structures.

Carbo-siloles, Part 2: Synthesis and Stereochemical Resolution of a Carbo-silolane Redox Equivalent

“…The angle between the Si-phenyl substituent planes of 8F (63 degrees) falls close to the range (79-84 degrees) observed in related crystallographic structures of hexaphenylsilole 16 or oligoacetylenic silanes. 17,18 The calculated bonds lengths are also in quite good agreement with related available X-ray diffraction data (Table I), thus validating the calculation level used for 8F and 10F. As previously recognized, 19 the calculated bond distances are just slightly longer than those suggested by X-ray diffraction data.…”

“…By contrast to the calculated planar SCHEME 5 Set of representative [5]pericyclynes and sila analogues studied either experimentally (2aF, 11), or computationally (8F, 9, 10F). a From reference [17]. b From reference [18].…”

Syntheses, Optical Properties and Photoactivated Insecticidal Activities of Cyclic Arylethynylsilanes

“…In order to avoid the hydrolysis of cyclic arylethynylsilanes, all these products were purified without aqueous workup. [9][10][11] Scheme 1 Synthesis of cyclic arylethynylsilanes 1a-1b Scheme 2 Synthesis of cyclic arylethynylsilanes 1c-1d…”

“…[1][2][3][4][5][6][7][8] Ethynyl-substituted tolans such as bis(2ethynylphenyl)ethyne (6) and bis(2,6-diethynylphenyl)ethyne (8) possess the geometry necessary to give cyclic structures when their di-and tetraanions are bonded to silicon atoms. [9][10][11][12] Delocalization of electrons is expected to be enhanced by the conjugated structures of cyclic arylethynylsilanes.…”

Dichlorodiisopropylsilane

“…30,31 Compared to Me 2 SiCl 2 , i-Pr 2 SiCl 2 gives much more robust protection due to the bulkiness of the two isopropyl groups, which slow hydrolysis of the Si-O bonds; compared to t-Bu 2 SiCl 2 , the reaction between i-Pr 2 SiCl 2 and a diol is smoother and usually gives higher yield; in addition, diols protected with i-Pr 2 SiCl 2 are easier to deprotect than those protected with t-Bu 2 SiCl 2 . Equation 11 shows an example of 1,3-diol protection using i-Pr 2 SiCl 2 ; stirring compound 12 with i-Pr 2 SiCl 2 in the presence of imidazole gave 13 in excellent yield. The i-Pr 2 Si group was later removed by HF-pyridine in THF at 0 • C for 3 h. 29…”