993-84-0Relevant articles and documents
The effect of substituents on the structure and reactivity of organogermanium anions
Pigarev, S. D.,Bravo-Zhivotovskii, D. A.,Kalikhman, I. D.,Vyazankin, N. S.,Voronkov, M. G.
, p. 29 - 42 (2007/10/02)
The replacement of the ethyl group in Et3GeH by a phenyl group was shown by equilibrium metallation to halve the pKa value compared with analogous CH acids.NMR showed that the decreased acceptor effect of the phenyl group in the PhEt2Ge- anion is caused by a considerably reduced contribution of the mesomeric effect to anion stabilization compared with what happens in the corresponding carbanions.At the same time, the stabilization of the organogermanium anion increases the role of ?-polarization of the aromatic substituent and this contribution is comparable with the mesomeric effect value.A stabilizing effect of organosilicon and organogermanium substituents due to a high degree of polarizability has been shown by concurrent methanolysis of Et3GeLi and REt2GeLi (R=Me3Si, Et3Si, Me3Ge, Et3Ge, t-Bu, Ph).An unexpected reaction of the trimethylsilyl anion with the Me3SiGeEt2- anion leading to diethylgermane dianion, Et2Ge2- has been revealed.The existence of this process supports the suggested absence of (d-p)? interaction in germanium anions with organo-silicon and -germanium substituents.
