X-ray crystallographic study of some pentacoordinated organogermanium compounds

Takeuchi, Yoshito; Pa̋rkányi, László; Kàlmán, Alajos; Nishikawa, Miki; Tanaka, Katsumi; Mori, Wasuke; Kinoshita, Masashi

doi:10.1016/j.jorganchem.2003.08.021

Cited by 8 publications

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References 10 publications

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“…For germanium bischelates 4 − 6 , the observed free energies Δ G ⧧ = 10.0−13.6 kcal·mol -1 (Table ) of enantiomerization for trigonal-bipyramidal intermediates are of the same order of magnitude as that observed for pseudorotation in pentacoordinated germanium complexes 19 with two bidentate chelate ligands, Δ G ⧧ = 12.3 (R = t -Bu) and 12.4 kcal·mol -1 (R = Ph), and substantially lower than those of 20 with tridentate ligand, 19.1 (R = Me) and 21.3 kcal·mol -1 (R = Ph)…”

Section: Resultsmentioning

confidence: 72%

Stereochemical Flexibility of Bis(amidomethyl)dichlorogermanes. A Novel Dissociative Mechanism of Ligand Exchange in Neutral Hexacoordinated Bischelate Complexes

et al. 2005

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A novel dissociative mechanism of (L,L)-ligand-site exchange in neutral hexacoordinated cis-(M←O) complexes of the type L2MX2 (M = Ge and Sn; X = Hal) is proposed. All the activation parameters of enantiomerization for (C,O)-chelate bis(amidomethyl)dichlorogermanes 4−6 have been determined by the dynamic NMR method. The fairly positive values of entropy for exchange in 4−6 (up to 17 cal·mol-1·K-1) suggest an interconversion of chelate ligands followed by a dissociative−associative mechanism. The correlation of activation barriers ΔG ⧧ 298 in hexacoordinate L2GeCl2 species (4−6) with intramolecular Ge←O distances in the crystals of analogous pentacoordinate LGeMe2Cl complexes with the same chelate ligand was found. A two-step process for intramolecular exchange including the dissociation of the coordinate Ge←O bond and pseudorotation in a pentacoordinate intermediate is considered as a model for the enantiomerization. It is shown that the main factor controlling the stereodynamic process in dichalogermanes 1−8 is pseudorotation B⇆B* for the pentacoordinate intermediate, while in the analogous tin complexes 9−12 it is the Sn←O bond rupture A⇆B in the primary hexacoordinate state.

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Section: Resultsmentioning

confidence: 72%

Stereochemical Flexibility of Bis(amidomethyl)dichlorogermanes. A Novel Dissociative Mechanism of Ligand Exchange in Neutral Hexacoordinated Bischelate Complexes

et al. 2005

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Germanium: Organometallic Chemistry

Holl¹,

Peck²

2005

Encyclopedia of Inorganic Chemistry

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This article provides an overview of the organometallic chemistry from 1994 to 2004. Major advances in the formation and breaking of GeC bonds are discussed, as are advances in the physical characterization of these compounds. Recent advances in the formation of organogermanium species containing multiple bonds to germanium and the formation of germanium‐centered radicals and cations are delineated. Applications to the synthesis of germanium‐containing polymers are overviewed.

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Germanimum: Organometallic Chemistry

Holl¹,

Peck²

2005

Encyclopedia of Inorganic Chemistry

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This article provides an overview of germanium organometallic chemistry from 1994 to 2007. Major advances in the formation and breaking of GeC bonds are discussed as are advances in the physical characterization of these compounds. Recent advances in the formation of organogermanium species containing multiple bonds to germanium and the formation of germanium‐centered radicals and cations are delineated. Applications to the synthesis of germanium‐containing polymers are overviewed.

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X-ray crystallographic study of some pentacoordinated organogermanium compounds

Cited by 8 publications

References 10 publications

Stereochemical Flexibility of Bis(amidomethyl)dichlorogermanes. A Novel Dissociative Mechanism of Ligand Exchange in Neutral Hexacoordinated Bischelate Complexes

Stereochemical Flexibility of Bis(amidomethyl)dichlorogermanes. A Novel Dissociative Mechanism of Ligand Exchange in Neutral Hexacoordinated Bischelate Complexes

Germanium: Organometallic Chemistry

Germanimum: Organometallic Chemistry

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