Absorption,electrochemical, theoretical,and 73Ge NMR spectral characterization of the germanium neo-pentane analogue (Me3Ge)4Ge

The germanium-based neo-pentane analogue (Me₃Ge)₄Ge has been characterized by UV/visible spectroscopy, cyclic voltammetry, and ⁷³Ge NMR spectroscopy as well as by density functional theory (DFT) calculations. The absorption maximum for (Me₃Ge)₄Ge is blue-shifted relative to those for other related branched oligogermanes (Ph₃Ge)₃GeH and (Ph₃Ge)₃GePh, and this species is also the most difficult to oxidize among these three compounds. DFT calculations indicate the HOMO of (Me₃Ge)₄Ge is stabilized relative to those for both tetragermanes by ca. 0.5 eV and therefore the theoretical and experimental results are in agreement. The ⁷³Ge NMR spectrum of (Me₃Ge)₄Ge exhibits two resonances and the feature corresponding to the central formally zero-valent germanium atom is shifted far upfield and was observed at δ ?339 ppm.     

Reactivity of α-germyl nitriles with acetonitrile: Synthesis, structures, and generation of Ph3Ge[NHC(CH3)CHCN] and 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine from Ph3GeCH2CN

The formation of 3-aminocrotononitrile and 4-amino-2,6-dimethylaminopyrimidine has been observed during the course of the hydrogermolysis reaction between a germanium amide and a germanium hydride, either as the free amines or bound to germanium as ligands consisting of their conjugate bases. These species arise from the dimerization or trimerization of acetonitrile, and have only been detected when germanium amides having substantial steric bulk at the germanium center are employed in the reaction. The isolation of germanium-bound 3-aminocrotononitrile compounds suggests that α-germyl nitrile species R₃GeCH₂CN that result from the reaction of the germanium amides R₃GeNMe₂ with CH₃CN solvent also can further react with CH₃CN to generate the 3-aminocrotononitrile and 4-amido-2,6-dimethylaminopyrimidine species. The two germanes Ph₃Ge[NHC(CH₃)CHCN] and 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine have been prepared and structurally characterized, and the conversion of Ph₃GeCH₂CN to Ph₃Ge[NHC(CH₃)CHCN] and 2,6-dimethylamino-4-(triphenylgermylamino)pyrimidine as well as the conversion of Ph₃Ge[NHC(CH₃)CHCN] to 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine in acetonitrile solvent has been observed using ¹H NMR spectroscopy.     

On the Reactivity of Metal and Organometallic Halides and Pseudohalides Towards Stannosiloxane (Ph3Sn-O-SiPh3)

Abstract

Interactions of HgX₂ (X = Cl, Br, I, SCN, CN, NCO), SbCl₃, TeCl₄, and PhTeCl₃ with Ph₃Sn-O-SiPh₃ at room temperature have been found to proceed with the simultaneous cleavage of Sn-O and Si-O bonds, invariably yielding Ph₂SnO, Ph₃SiX, and the corresponding organo-mercury, -antimony, and -tellurium derivatives. The course of the reactions suggests the instability of the Sn-O-M (M = Hg, Sb, Te) system.

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Ge–Ge Bond-Forming Reactions from Bis(germyl)palladium Complexes with Chelating Diphosphine Ligands

Abstract

Ge–Ge bond-forming reactions of bis(germyl)palladium complexes with chelating diphosphine ligands have been investigated. Addition of excess dmpe (1,2-bis(dimethylphosphino)ethane) to the solution of Pt(GeHPh₂)₂(dmpe) (1) gave a mixture of oligogermanes in low yields, while a similar reaction of depe (1,2-bis(diethylphosphino)ethane) with Pt(GeHPh₂)₂(depe) (2) afforded H(GePh₂)₂H selectively in 93% NMR yield.

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Metalloid Cluster Compounds of Group 14: Bonding Properties and Subsequent Reactions

Abstract

Metalloid cluster compounds of group 14 of the general formulae E_nR_m with n > m (E = Si, Ge, Sn, Pb; R = ligand), where naked as well as ligand bound tetrel atoms are present, represent a novel class of cluster compounds in group 14 chemistry and can be seen as intermediates on the way to the elemental state. Therefore, interesting properties are expected for these compounds, which might complement results from nanotechnology. In this article, first results for germanium are discussed, together with novel build-up reactions on the way to novel materials based on metalloid cluster compounds.

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Phénylhalogénohydrodigermanes

The symmetric and unsymmetric phenylchlorohydrodigermanes can be isolated or characterized via partial halogenation of the Ge? H bonds of the symmetrical phenylhydrodigermanes Ph₂(H)GeGe(H)₂Ph, Ph(H)₂GeGe(H)₂Ph by chloromethyl methyl ether and carbontetrachloride. Some of these phenylchlorohydrodigermanes are formed by insertion of phenylchlorogermylene (PhGeCl) on the Ge? H or Ge? Cl bonds of the phenylchlorohydrogermanes. The hydrolysis of the monochloro phenylhydrodigermanes Ph₂(Cl)GeGe(H)₂ and Ph(Cl)(H)GeGe(H)₂Ph leads to the phenyl phenylhydrogermyl digermoxanes [Ph₂(H)GeGePh₂]₂O and [Ph(H)₂GeGe(H)Ph]₂O. Treatment of these oxides with the concentrated aqueous solutions of hydracides leads to the monofluorinated, brominated and iodinated phenylhydrodigermanes Ph₂(H)GeGe(X)Ph₂ and Ph(H)₂GeGe(H)(X)Ph (X) = F, Br, I). Phenylchlorohydrodigermanes decompose thermally by α-elimination on one germanium atom with formation of germylene and phenylchlorohydrogermane. The physico-chemical IR. and NMR. study of these phenylhalogenohydrodigermanes indicates that, if the vGe? H frequency variations are mostly linked to the inductive effects of the substituents on the same germanium, the variations of the chemical shifts of the Ge? H protons seem to be due to many factors and especially to the inductive effect of the substituents on the germanium and the magnetic anisotropy of the Ge? X bonds.     

The germanium(II) ate complex [Ph3PiPr][Ge(OCOMe)3]: the first structurally characterized compound containing a discrete [E14(II)O3](−) (E14(II) = Si,Ge, Sn or Pb) anion

An X‐ray diffraction study reveals an unusual structure of the new thermally stable germanium(II) ate complex [Ph₃PⁱPr][Ge(OAc)₃] (4) containing a discrete [Ge(OAc)₃]^(?) anion containing monodentate acetate ligands with a trigonal pyramidal germanium centre. Copyright © 2005 John Wiley & Sons, Ltd.     

Über polygermane: XIV. Polygermane als nebenprodukte der Grignard-reaktion von PhMgBr mit GeCl4

The synthesis of GePh₄ and Ge₂Ph₆ by Grignard reaction in THF or ether/toluene leads to the by-products Ge₃Ph₈ (up to 11%) and Ge₄Ph₁₀ (up to 18%) which is dependant on using an excess of Mg. A quantitative analysis of the resulting products by HPLC and a semipreparative separation by column, flash, and HPL chromatography is described. The crystal structures of Ge₃Ph₈ (R = 0.075) and Ge₄Ph₁₀ · 2C₆H₆ (R = 0.054) have been determined. Ge₄Ph₁₀ has C_i symmetry and both chain conformations are well staggered (49–70° for Ge₃Ph₈, 53–66° for Ge₄Ph₁₀). The GeGe distances and GeGeGe angles are 244 pm and 121° (Ge₃Ph₈), and 246 pm and 118° (Ge₄Ph₁₀).     

Über polygermane: XV. Darstellung von phenylierten trigermanen in HMPT

The optimum conditions for the synthesis of the trigermanes Ge₃Ph₈ and Ge₃Me₂Ph₆ according to R₂GeCl₂ + 2 Ph₃GeAk (Ak = Li, K) in HMPT have been determined. The main difficulty is to repress a nucleophilic attack of Ph₃Ge⁻ at newly formed GeGe bonds. The mass spectrum of Ge₃Me₂Ph₆ shows rearrangements of the GePh₃ and Ph/Me groups. The ¹³C NMR phenyl signals of di-, tri- and tetra-germanes are nearly identical. Ge₃Ph₈ and Ge₄Ph₁₀ transform to the plastically-crystalline state before melting (ΔH 45.3 and 54.9 kJ mol⁻¹). The crystal structure of Ge₃Me₂Ph₆ has been determined. The molecule has C₂ symmetry (GeGe 242.9(1) pm, GeGeGe 120.3(1)°).     

Über polygermane: XVI. Synthese α,ω-dichlorierter polygermane Cl(Ph2Ge)nCl (n = 2,3,4) durch germylen-einschub

The germylene Ph₂Ge of Ph₂GeHCl and Net₃ inserts in excess Ph₂GeHCl and forms polygermanes Cl(Ph₂Ge)_nH. This one-pot reaction and subsequent chlorination to Cl(Ph₂Ge)_nCl has been optimized. Increasing amounts of NEt₃ step up the yields of higher polygermanes. The ¹³C NMR phenyl signals for C(ipso) shift to low field with increasing chain length. The crystal structures of Cl(Ph₂Ge)_3,4Cl (R = 0.072 and 0.087) have been determined. The position of Cl(Ph₂Ge)₄Cl is split off by disorder (main molecule 82%, side molecule 18%). Two crystallographically different molecules of the trigermane are present; the ClGe₃Cl chain contains anti-gauche and gauche-gauche conformation respectively (distances GeGe 241.3–243.7 pm, angles GeGeGe 110.4 and 116.7°). The ClGe₄Cl chain is centrosymmetric and has all-anti conformation (distances GeGe 245.0 and 244.2 and 244.2 pm, angle GeGeGe 116.2°).     

A One-Pot Synthesis of Functionalized 2,3-Dihydrothiazoles from Isothiocyanates,Primary Alkylamines,and Phenacyl Bromides

Abstract

A simple, one-pot synthesis of N-(4-aryl-3-alkylthiazol-2(3H)-ylidene)anilines and N-(4-aryl-3-alkylthiazol-2(3H)-ylidene)benzamides via the reaction of primary alkylamines, α-bromoketones, and phenylisothiocyanate or benzoylisothiocyanate is described.

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Phosphorus Containing Ions with Unconventional Structure: El-Fragmentation of Et3P(S)

Abstract

Gas phase ion structures often do not correlate with those of their corresponding neutrals and many ions with unconventional structures have been found to be stable in the gas phase in contrast to their neutral counterparts. Thus, radical ions (a) and (b)

are formed under EI-conditions by consecutive elimination of C₂H₄ from ionized triethylphosphanesulfide Et₃P(S). (a) contains tricoordinated phosphorus while the structure of (b) corresponds to an ionized adduct of H₂S and the “phosphinidene” Et - P. The structures have been determined on the basis of collisional activation and metastable ion spectra as well as H/D-exchange reactions. Results of semiempirical MO-calculations (MNDO) are reported.     

Organogermanium(II) Hydrides as a Source of Highly Soluble LiH

The reactions of monomeric C,N-chelated organogermanium(II) hydride L(H)Ge ⋅ BH₃ with organolithium salts RLi yielded lithium hydrogermanatoborates (Li(THF)₂{BH₃[L(H)GeR]})₂. Compound (Li(THF)₂{BH₃[L(H)GePh]})₂ was used as a source of LiH for the reduction of organic C=O or C=N bonds in nonpolar solvents accompanied by the elimination of a neutral complex L(Ph)Ge ⋅ BH₃. The interaction of (Li(THF)₂{BH₃[L(H)GePh]})₂ with the polar C=O bond was further investigated by computational studies revealing a plausible geometry of a pre-reactive intermediate. The experimental and theoretical studies suggest that, although the Li atom of (Li(THF)₂{BH₃[L(H)GePh]})₂ coordinates the C=O bond, the GeH fragment is the active species in the reduction reaction. Finally, benzaldehyde was reduced by a mixture of L(H)Ge ⋅ BH₃ with PhLi in nonpolar solvents.     

Synthesis of Poly(amidoamine) Dendrimer with a Diphenyl Diselenide Core

Abstract

We succeeded in the synthesis of a novel poly(amidoamine) dendrimer having diphenyl diselenide at the core. Modification of the dendrimer diselenide by the reaction with glucono-δ-lactone in methanol gave a water-soluble dendrimer diselenide having chiral terminal groups. The structures of dendrimers were satisfactorily confirmed by MAIDI-TOF MS spectrometry, elemental analysis, and NMR spectroscopy. Interestingly, induced circular dichroism (ICD) of the interaction between the diphenyl diselenide core and D-gluconamide periphery of the dendrimer was observed at 300 nm.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

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Synthesis and Spectroscopic Evaluation of Novel N-, S-, and O-Substituted 1,4-Naphthoquinone Derivatives

Abstract

Novel O- S,O- S,S- N,N- and N,S-substituted naphthoquinone compounds were prepared by reaction of 2,3-dichloro-1,4-naphthoquinone and the corresponding nucleophiles in the presence of chloroform and triethylamine or ethanol solution of Na₂CO₃. The structures of the novel naphthoquinone compounds were characterized by micro analysis, FT-IR, UV/Vis, ¹H NMR, ¹³C NMR, MS, and fluorescence spectroscopy.

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Germanium(II)‐, Zinn(II)‐ und Blei(II)‐Derivate des polycyclischen Alumosiloxans [Ph2SiO]8[Al(O)OH]4

Germanium(II)‐, Tin(II)‐ and Lead(II)‐Derivatives of the polycyclic Alumosiloxane [Ph₂SiO]₈[Al(O)OH]₄ Five new derivatives of the polycyclic alumosiloxane [Ph₂SiO]₈[Al(O)OH]₄ have been synthesized by replacement of the protic hydrogen atoms on the hydroxy‐groups attached to the aluminium atoms by the divalent group 14 elements germanium, tin and lead. The compounds can be divided in those with one metal atom per alumosiloxane moiety, [Ph₂SiO]₈[Al(O)OH]₂[AlO₂]M (M=Ge, Sn), and those with complete substitution of the protic hydrogen atoms by metal atoms like [Ph₂SiO]₈[AlO₂]₄M₂ (M= Sn, Pb). Always one element of the series Ge, Sn, Pb is missing in the two types of compounds. Crystal structure analyses of [Ph₂SiO]₈[Al(O)OH]₂[AlO₂]₂M · 2 C₄H₈O₂ (M= Ge ( 1 ), Sn ( 2a )), [Ph₂SiO]₈[Al(O)OH]₂[AlO₂]₂Sn · 2 THF ( 2b ) and [Ph₂SiO]₈[AlO₂]₄M₂ (M= Sn ( 3 ), Pb ( 4 )) have been performed elucidating either polycyclic basket‐type ( 1 , 2a , 2b ) or closed polyhedral structures ( 3 , 4 ).     

NBO,NMR Analysis,and Hybrid DFT Study of Structural and Configurational Properties of Di-tert-butyl-, bis(trimethysilyl)-, Bis(trimethgermyl)-, and Bis(trimethylstannyl)- cyclopenta-1,3-dienes

Abstract

The alkyl 1,2-shift in di-tert-butylcyclopenta-1,3-diene (1) and the metallotropic 1,2-shifts in bis(trimethylsilyl)cyclopenta-1,3-diene (2), bis(trimethylgermyl)cyclopenta-1,3-diene (3), and bis(trimethylstannyl)cyclopenta-1,3-diene (4) have been investigated by means of natural bond orbital (NBO), nuclear magnetic resonance (NMR) analysis, and hybrid density functional theory based methods. The B3LYP/DZVP results showed that the M(CH₃)₃ group [M = C (1), Si (2), Ge (3), and Sn (4)] migration barrier heights around cyclopentadienyl rings decrease from di-tert-butylcyclopenta-1,3-diene to its stannane derivative. Also, based on the results obtained, the stabilities of the 5,5-isomers in comparison to the 1,5- and 2,5-isomers increase from di-tert-butylcyclopenta-1,3-diene to its stannane derivative. The results suggest that in these compounds the metallotropic shifts are controlled by the stabilization energies associated with σ→π* electron delocalizations and the increase of the σ_C5-M→π*_C1-C2 electron delocalizations facilitates the M(CH₃)₃ group migrations around cyclopentadienyl rings. Based on the aromatic stabilization energy (ASE) values calculated, the aromaticity increases from the 5,5-isomers of di-tert-butylcyclopenta-1,3-diene to its stannane derivative but the variation of the nucleus-independent chemical shift, NICS(0) and NICS(1), values calculated are not in accordance with the ASE values calculated and the σ_C5-M→π*_C1-C2

electron delocalizations. The correlations between the sigmatropic shift barrier heights, σ→π* electron delocalizations, ASE, and NICS values were investigated.

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