S. Richelme

Spectres de vibration de composes organiques des elements de la colonne IV B : XII - Organopolygermanes☆

Abstract An investigation and interpretation is presented of the infra-red and Raman vibrational spectra of sixteen organic compounds with a GeGe bond. Some compounds of these series were specifically synthesized for this study. An assignment can be given to most observed bands. Particular attention is given to the discussion of the position of vibration frequencies υ(GeGe) and υ(GeH). From a comparison of the υ(SiH) and υ(GeH) frequencies it may be stated that the (p → d) π and (d-d) π interactions which can occur in some compounds are weaker in the case of digermanes than for disilanes.

Addition des phenyl- et phenylchloro-germanes sur les amines: N- et C-germylamines; germa-aziridines

Abstract In the addition reactions of germanes on imines, we observed the radical N -germylation in the case of triphenyl- and diphenylchloro-germanes; but in the case of chlorogermanes which show an “acidic character” as PhCl 2 GeH, we observed a dipolar C -germylation. The trichlorogermane gives only a dehydrochlorination reaction by abstraction of HCl (α-elimination) with formation of dichlorogermylene Transient germaziridines formed in the dehydrochlorination reaction of the transient species can be also characterized in the action of aminolithium compounds on chlorogermylalkychlorides: .

The intensity of GeH stretching modes in the IR spectra of organogermanium compounds R′2GeH2

Abstract The integrated intensity ( A ) of GeH stretching modes in the IR spectra of 20 compounds of the type R 2 GeH 2 , RXGeH 2 and X 2 GeH 2 containing substituents R which are incapable of d π  p π -interaction with the germanium atom, and substituents X which do form d π  p π -bonds with the germanium atom, has been studied. It has been shown that for R 2 GeH 2 compounds the values of A 1 2 are related to the sum of the Taft constants σ * of the three substituents R(Σσ * ) by the equation A 1 2 = 1.79 − 0.2 Σσ * . For compounds RXGeH 2 and X 2 GeH 2 the experimental values of intensity A 1 2 exp differ from A 1 2 ind as a result of the d π  p π -character of GeX bonds. The differences Δ A 1 2 = A 1 2 exp − A 1 2 ind describe the effect of d π  p π -interaction which increases with increasing effective positive charge on the germanium atom. Confirmation of the less pronounced ability of the germanium atom to undergo d π — p π -interaction in comparison with the silicon atom has been obtained.

Infrared study of intramolecular coordination in (chloromethyl)- and (dichloromethyl)-germanes

Abstract Frequencies (ν) and integrated intensities ( A ) of GeH stretching modes in the IR spectra of (diorgano)germanes containing GeCH 2 Cl and GeCHCl 2 fragments have been measured. Anomalous values of ν and A (compared to those expected from the inductive effect only) are explained by intramolecular coordination between chlorine and germanium atoms. The enthalpy of intramolecular coordination (Δ H ) has been determined by IR spectroscopy. The enthalpy of intramolecular coordination is shown to increase with the acceptor properties of the substituents bonded to the germanium atom in (dorgano)- and (triorgano)-germanes.

Application of electronic and ir spectroscopy to the determination of σp-, σ+p- and σoR-constants of some organosilicon and organogermanium substituents☆

Abstract The σ p - and σ + p - constants of some silicon- and germanium-containing substituents have been determined from electronic absorption spectroscopy data of charge-transfer (CT) complexes of phenylgermanes, benzylsilanes and benzylgermanes with tetracyanoethylene (TCNE). Resonance constants of corresponding substituents have been determined from the integrated intensity values of aromatic ring stretching modes (IR spectroscope data) of benzylsilanes and benzylgermanes. It is shown that the effect of d π p π interaction in phenylgermanes remains practically unchanged in the course of the transition from the ground state to the CT state. The high negative values of σ + p -constants for benzylorganosilicon and benzylorganogermanium substituents indicate the presence of considerable σ, π-conjugation in the CT state of benzylsilanes and benzylgermanes. This effect is also established for the ground state of the above mentioned compounds from their σ o R -values. The effect of σ,π-conjugation is displayed in greater degree in the ground state as well as in the CT state in benzylgermanes as compared with benzylsilanes.

Infrared study of intramolecular coordination in organogermanium compounds

Abstract Frequencies (ν) and integrated intensities A of GeH stretching modes in the IR-spectra of germanes, containing GeCH 2 Cl and GeCHCl 2 , have been measured. The doublet character of the ν(GeH) absorption bands has been explained by intramolecular coordination (α-effect) between the chlorine and germanium atoms. The influence of solvents (heptane, carbon tetrachloride, tetrahydrofuran, acetone) on the shape of the ν(GeH) absorption bands has been considered. The factors influencing the intensity of coordinated ν(GeH) absorption bands have been analysed. The enthalpy of intramolecular coordination (δ H ) has been determined by spectroscopy. It has been shown that the α-effect enthalpy increases with the increase of the acceptor properties of substituents bonded to the germanium atom.

Integrated intensity of GeH stretching modes and dπpπ interaction in trisubstituted germanes (Ri)3GeH

The integrated intensity (A) of GeH stretching modes in IR spectra of 30 trisubstituted germanes (Ri)3GeH, has been studied. For R3GeH compounds in which the R substituents do not form dπpπ bonds with the germanium atom, the correlation between A1/2 and the sum of inductive Σσ* constants of the Ri substituents has been established. The contributions made by conjugation effects of a germanium atom with the Ri substituents to the integrated intensity of v(GeH) bands are estimated. The formation of weak labile complexes of (p → d)σ triorganogermanes with carbon tetrachloride has been studied. The values of v(GeH) intensity are compared with the data on disubstituted germanes (Ri)2GeH2 and silane derivatives (Ri)3SiH.

Steric effects in the ir-spectra of silicon and germanium mesityl derivatives

Abstract Frequencies (v) and integrated intensities (A) of MH (M  Si, Ge) stretching modes in IR spectra of organosilicon and organogermanium compounds, containing phenyl, xylyl and mesityl substituents, have been measured. In contrast to phenyl and xylyl derivatives, the influence of mesityl substituents on v(MH) and A(MH) is shown to be determined not only by the inductive effect and dπpπ interaction, but also by the pronounced steric effects of mesityl groups.

Etude structurale de trialkylalcoxy-ou aryloxygermanes et d'oxydes de trialkylgermyle : I. Determination des polarisations atomiques de tetraalkylgermanes et d'oxydes de trialkylgermyle

Abstract The atomic polarizations of tetraalkylgermanes and oxides have been determined. The total molecular polarizations are measured by dipolarimetry at various temperatures; the electronic polarizations have been obtained from dispersion of the refractive index.

Etude structurale de trialkylalcoxy- ou aryloxygermanes et d'oxydes de trialkylgermyle : II. Influence du solvant sur les polarisations atomiques des oxydes de trialkylgermyle: Determination par dipolemetrie des angles GeOC et GeOGe

Abstract The dipole moments of trialkylalkoxygermanes, phenoxy- and p -chlorophenoxygermanes of the type R 3 GeOR′ with R = Me, Et, Pt, Bu, and R′ = Me, t-Bu, Ph, p -ClPh, and also the trialkylgermanyl oxide compounds of the type R 3 GeOGeR 3 with R = Me, Et, Pr, have been determined in both cyclohexane and benzene. As a result of studies at various temperatures (25,45,65°C) we were able to measure the atomic polarization. These data indicate an important variation with the nature of the solvent. It is observed that oxygen valence angles change with the nature of the substituents and that the moments of the R 3 GeO groups are modified only slightly irrespective of the nature of R or the solvent.