72176-49-9Relevant articles and documents
Organogermanium reactive intermediates. The direct detection and characterization of transient germylenes and digermenes in solution
Leigh, William J.,Harrington, Cameron R.,Vargas-Baca, Ignacio
, p. 16105 - 16116 (2007/10/03)
Diphenylgermylene (Ph2Ge) and its Ge=Ge doubly bonded dimer, tetraphenyldigermene (6a), have been characterized directly in solution for the first time by laser flash photolysis methods. The germylene is formed via (formal) cheletropic photocycloreversion of 3,4-dimethyl-1,1- diphenylgermacyclopent-3-ene (4a), which is shown to proceed in high chemical (>95%) and quantum yield (Φ = 0.62) by steady-state trapping experiments with methanol, acetic acid, isoprene, and triethylsilane. Flash photolysis of 4a in dry deoxygenated hexane at 23°C leads to the prompt formation of a transient assigned to Ph2Ge (∈max = 500 nm; ∈max = 1650 M-1 cm-1), which decays with second-order kinetics (τ ≈ 3 μs), with the concomitant growth of a second transient species that is assigned to digermene 6a (τ ≈ 40 μs; λmax = 440 nm). Analogous results are obtained from 1,1-dimesityl- and 1,1-dimethyl-3,4-dimethylgermacyclopent-3-ene (4b and 4c, respectively), which afford Mes2Ge (τ = 20 μs; λmax = 560 nm) and Me2Ge (τ ≈ 2 μs; λs; λmax = 480 nm), respectively, as well as the corresponding digermenes, tetramesityl- (6b; λmax = 410 nm) and tetramethyldigermene (6c; λmax = 370 nm). The results for the mesityl compound are compared to the analogous ones from laser flash photolysis of the known Mes2Ge/6b precursor, hexamesitylcyclotrigermane. The spectra of the three germylenes and two of the digermenes are in excellent agreement with calculated spectra, derived from time-dependent DFT calculations. Absolute rate constants for dimerization of Ph2Ge and Mes2Ge and for their reaction with n-butylamine and acetic acid in hexane at 23°C are also reported.
New (diarylgermyl)lithiums
Castel,Riviere,Satge,Ko
, p. 205 - 210 (2008/10/08)
The new (diarylgermyl)lithiums R2GeHLi (2; R = phenyl, mesityl) were prepared in good yields by hydrogermolysis reactions of tert-butyllithium in THF. The stability of compounds 2 depends on the nature of the R group and the solvent. For R = Ph, in the presence of an amine (Et3N or Et2NMe), the same reaction leads to the formation of the polygermanes H(GePh2)nH (n = 2-4). The characterization of compounds 2 by IR and 1H and 13C NMR spectroscopy and their complexation with a crown ether are also reported. They are characterized by deuterolysis and alkylation reaction (with MeI and Me2SO4). Their germylation reactions with Ge-Cl reagents constitute a convenient way for synthesizing organo-hydropolygermanes. Compounds 2 also react with acyl chlorides to give new germyl ketones, R2HGeCOR′, and the unexpectedly stable β-germyl diketone Ph2Ge(COMes)2.
Synthesis of the first germa-1-pyrazoline and its decomposition via a germirane intermediate
Egorov, M. P.,Kolesnikov, S. P.,Nefedov, O. M.,Krebs, A.
, p. C5 - C8 (2007/10/02)
The first germapyrazoline, 4-germa-1-pyrazoline (2), has been obtained by cycloaddition of diazomethane to the Ge=C bond of the germene (1).Thermal or photochemical decomposition of 2 via a germirane intermediate (4) gives 9-methyl-enefluorene and dimesitylgermylene, which can be trapped by 2,3-dimethylbutadiene.
