Marszaukowski F, Wohnrath K, Boeré RT. Bulky 2,6-disubstituted aryl siloxanes and a disilanamine.
Acta Crystallogr E Crystallogr Commun 2020;
76:318-323. [PMID:
32148868 PMCID:
PMC7057366 DOI:
10.1107/s2056989020001413]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 01/31/2020] [Indexed: 12/01/2022]
Abstract
The crystal structures of 5-bromo-1,3-di-tert-butyl-2-[(tri-methyl-sil-yl)-oxy]benzene, C17H29BrOSi, (I), 1,3-di-tert-butyl-2-[(tri-methyl-sil-yl)-oxy]benzene, C17H30OSi, (II), and N-(2,6-diiso-propyl-phen-yl)-1,1,1-trimethyl-N-(tri-methyl-sil-yl)silanamine, C18H35NSi2, (III), are reported. Compound (I) crystallizes in space group P21/c with Z' = 1, (II) in Pnma with Z' = 0.5 and (III) in Cmcm with Z' = 0.25. Consequently, the mol-ecules of (II) are constrained by m and those of (III) by m2m site symmetries. Despite this, both (I) and (II) are distorted towards mild boat conformations, as is typical of 2,6-di-tert-butyl-substituted phenyl compounds, reflecting the high local steric pressure of the flanking alkyl groups. Compound (III) by contrast is planar and symmetric, and this lack of distortion is compatible with the lower steric pressure of the flanking 2,6-diisopropyl substituents.
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