Tetrahedral molecular geometry

About: Tetrahedral molecular geometry is a research topic. Over the lifetime, 1795 publications have been published within this topic receiving 30706 citations.

Titanium Amino Alcohol Complexes from α-Titanic Acid: X-Ray Crystal Structure of Titanium Bis[2,2´-(methylimino)diethanolate]

Abstract: A method for producing amino alcohol complexes of titanium from hydrated titania (α-titanic acid) is described. Thus hydrated titania was completely converted into triethanolamine and diethanolamine complexes during reaction at 120°C for 6 h. This represents a synthetic method for titanium sol–gel precursors which are free from chlorine-containing impurities. Products were characterized with assistance from 1 H and 13 C nuclear magnetic resonance spectroscopy, and electrospray mass spectrometry. A single-crystal X-ray structure of titanium bis[2,2´- (methyl-imino)ethanolate], tetragonal, space group P4 – 2 1 c, is presented. The titanium centre is coordinated by an N2O4 donor set which can be most closely described as a bifacially capped tetrahedral geometry.

Ab initio calculations on potential intermediates in metal reductions of carbonyl compounds. Stereochemical considerations

Abstract: Conformational preferences of ketyls, hydroxyalkyl radicals, and hydroxyalkyl carbanions derived from propionaldehyde and cyclohexanone have been studied with ab initio molecular orbital calculations. Each species is significantly pyramidalized toward a tetrahedral geometry, and there is staggering about the single bonds to the pyramidal center. For the 1-hydroxypropyl radical, there is little conformational preference about the C 1 -C 2 bond

Nucleophilic displacement at the benzoyl centre: a study of the change in geometry at the carbonyl carbon atom

Abstract: The second-order rate constants for the reaction between hydroxide ion and phenoxide ion with 4-nitrophenyl esters of substituted benzoic acids in 10% acetonitrile–water (v/v) solution obey Hammett σ correlations. The values of the Hammett ρ of 1.67 (kArO) and 2.14 (kOH) are consistent with a large change in hybridization at the central carbon by comparison with the ρ value for a standard reaction where a full sp2 to sp3 change occurs. The transition state for the concerted reaction thus has a substantially tetrahedral geometry. The observation of the anti-Hammond effect whereby the ρ value for the hydroxide ion exceeds that of the less reactive phenoxide ion is consistent with a concerted, ANDN, mechanism for these reactions. A stepwise mechanism, AN + DN, is unlikely to yield a measurable break in the Hammett correlation for a change in the benzoyl substituent if the partitioning of the putative tetrahedral intermediate involves forward and reverse reactions with Hammett correlations possessing similar ρ values.