Dianionic Tris[oxalato(2—)]silicate and Tris[oxalato(2—)]germanate Complexes: Synthesis,Properties, and Structural Characterization in the Solid State and in Solution

Reaction of tetramethoxysilane with three molar equivalents of oxalic acid and two molar equivalents of 1‐(2‐hydroxyethyl)‐pyrrolidine or 1‐(2‐hydroxyethyl)piperidine in tetrahydrofuran yielded the λ⁶Si‐silicates 1‐(2‐hydroxyethyl)pyrrolidinium tris[oxalato(2—)]silicate ( 4 ) and 1‐(2‐hydroxyethyl)piperidinium tris[oxalato(2—)]silicate ( 5 ). The related germanium compounds 1‐(2‐hydroxyethyl)piperidinium tris[oxalato(2—)]germanate ( 6 ) and triethylammonium tris[oxalato(2—)]germanate ( 7 ) were synthesized analogously, starting from tetramethoxygermane and using three molar equivalents of oxalic acid and two molar equivalents of 1‐(2‐hydroxyethyl)piperidine or triethylamine. Compounds 4 — 7 were characterized by elemental analyses (C, H, N), single‐crystal X‐ray diffraction, solid‐state VACP/MAS NMR spectroscopy (²⁹Si), and solution NMR spectroscopy (¹H, ¹³C, ²⁹Si). The structural characterization was complemented by computational studies of the tris[oxalato(2—)]silicate dianion and the tris[oxalato(2—)]germanate dianion. In addition, the stability of compounds 4 — 7 in aqueous solution was studied by ¹³C NMR spectroscopy.     

Synthesis of Germanium Oligomer from Germanium Dioxide

Several crystalline germanium oligomers Ge_nO_2n+1· L₂·xH₂O (L = amino acid or amine) have been prepared and characterized by IR and NMR spectra, EA (elemental analysis), TGA (thermogravimetric analysis) and ICP-AES (inductively coupled plasma-atomic emission spectroscopy). Oligomers of this type are based on chains of germanium-oxygen single and double bonds and synthesized in aqueous solution from germanium dioxide and basic ligands having an amino group. Two basic amino acids and mono-, and bidentate amines chosen as ligands to react with germanium dioxide gave L-lysine germanate (1a, 1b, 1c), L-arginine germanate (2a, 2b, 2c), Cyclohexylammonium hexagermanate (3), N-methylcyclohexylammonium hexagermanate (4), N,N-dimethylcyclohexylammonium hexagermanate (5), 2-aminoethylammonium trigermanate (6), 2-N′-methylammo)-N-methylethylammonium pentagermanate (7), 2-(N′N′-dimethylamino)-N′N-dimethylethylammonium heptagermanate (8).     

Compound formation in the System PbGeO3?Pb5Ge3O11

Compound formation in the system PbGeO₃? Pb₅Ge₃O₁₁ was studied by thermal analysis and high-temperature X-ray diffraction. New modifications of PbGeO₃ and Pb₅Ge₃O₁₁ were prepared by the simultaneous hydrolysis of lead and germanium alkoxides, followed by washing and drying; the former has a hexagonal unit cell with a = 15.573 Å and c = 7.240 Å, and the latter has an orthorhombic crystal structure with a = 5.081 Å, b = 7.301 Å and c = 8.817 Å. They are transformed to the known monoclinic and hexagonal modifications at 575 to 610°C and 410 to 450°C, respectively. No compound of Pb₃Ge₂O₇ was confirmed. The structures of germanate groups in the lead germanate compounds are discussed on the basis of the infrared spectral data.     

Synthesis and crystal structure of a novel germanate: (NH4)4[(GeO2)3(GeO1.5F3)2].0.67H2O

The novel microporous germanate (NH4)4[(GeO2)3(GeO1.5F3)2].0.67H2O was prepared from an aqueous solution containing germanium dioxide, pyridine, hydrofluoric acid, and 2,6-diaminopyridine as a template. The solution was kept at 165 degrees C in a Teflon-lined autoclave for 4 days. Large crystals were produced and studied by X-ray powder diffraction, FTIR, thermal analysis, and elemental analysis. The structure was determined by single-crystal X-ray diffraction. The crystal is orthorhombic, space group Pbcn, with a = 7.0065(4) A, b = 11.7976(6) A, c = 19.5200(14) A, and Z = 4. The structure is a layered framework built up from GeO4 tetrahedral and GeO3F3 octahedral units. The polyhedral units are connected in such a way that they form a zeolite-like porous structure with three- and nine-membered rings. Half of the ammonium ions are located inside the nine-membered rings. The other half are above and below the three-membered rings. The connectivity of the germanium polyhedral units is interrupted along the c axis by ammonium ions and water molecules inserted between the layers.     

Behavior of tri(n-butyl)ammonium bis[citrato(3-)-O1,O3,O6]silicate in aqueous solution: analysis of a sol-gel process by small-angle neutron scattering

The racemic hexacoordinate silicon(IV) complex tri(n-butyl)ammonium bis[citrato(3-)-O1,O3,O6]silicate (1) was synthesized by treatment of Si(OMe)4 with 2 molar equiv of citric acid and 2 molar equiv of N(n-Bu)3. The corresponding germanium analogue, tri(n-butyl)ammonium bis[citrato(3-)-O1,O3,O6]germanate (5; structurally characterized by single-crystal X-ray diffraction), was obtained analogously, starting from Ge(OMe)4. Upon dissolution in water, the lambda6Si-silicate dianion of 1 hydrolyzes spontaneously (formation of Si(OH)4 and citric acid), whereas the lambda6Ge-germanate dianion of 5 was found to be stable in water. Aqueous "solutions" of 1, with concentrations that are significantly higher than the saturation concentration of Si(OH)4, look absolutely clear over a period of several weeks; however, in reality, these solutions are sols with very small particles that slowly grow with time and finally form a gel that precipitates. This sol-gel process was monitored by small-angle neutron scattering (SANS). For reasons of comparison, an aqueous solution of the hydrolytically stable germanium compound 5 was also studied by the SANS technique.     

Syntheses and Crystal Structures of Bis-Citrato,Bis-Citramalato and Bis-Malato Germanate(IV) Complexes

Bis-citrato 1a-d , bis-citramalato 2 and bis-malato 3 germanate(IV) complexes were synthesized from germanium dioxide and citric acid, citramalic acid and malic acid respectively and were identified with IR, NMR and elementary analysis. Crystal 1a is triclinic, space group P1 with a = 7.919(2), b = 7.968(3), c = 9.605(3) Å, α = 94.25(3), β = 108.03(2), γ= 113.05(3)°, Z = 1, and the final residue, R(F), is 0.033 for 2583 reflections. Crystal 2 is monoclinic, space group C2 with a = 10.226(4), b = 12.802(4), c = 6.141(1) Å, β = 100.75(2)°, Z = 2, and the final residue, R(F), is 0.034 for 934 reflections. Both 1a and 2 have slightly distorted octahedral structures with citrate or citramalate ions as a tridentate ligand that forms five-, six- and seven-membered rings with the central metal. There is a two-fold axis through the central atom of compound 2 instead of the inversion center of 1a . Same structures for these six complexes are indicated because the spectral patterns of the other four compounds, 1b-d and 3 , are similar to those of compounds 1a and 2 .     

Crystalline Anionic Germanate Covalent Organic Framework for High CO2 Selectivity and Fast Li Ion Conduction

The metalloid-centered covalent organic framework has attracted great interest from both its structure and application. Heavier elements have seldomly been incorporated in the covalent organic frameworks, even if they exhibit special structural features and properties. Herein, we reported the first crystalline germanate covalent organic framework with hexacoordinated germanate linked by an anthracene linker. The existence of counterion lithium ions in the framework provides a high CO₂ uptake of 88.5 cm³ g⁻¹ at 273 K and a high CO₂/N₂ selectivity of 101. A significantly improved lithium ion conductivity of 0.25 mS cm⁻¹ at room temperature was observed due to the soft germanium center.     

Synthesis, structural characterization, and thermal stability of a new layered germanate structure, Na4Ge16O28(OH)12

The new layered germanate structure Na4Ge16O28(OH)12 has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, FTIR, and SEM. The crystal lattice parameters are a = 7.3216(6) A, b = 14.3986(9) A, c = 7.7437(6) A, alpha = 90.0 degrees, beta = 100.179(7) degrees, gamma = 90.0 degrees, and V = 803.5(1) A3. The space group is C2/m with Z = 1. The germanium oxide sheets are connected non-covalently via electrostatic interactions with the sodium cations and H-bridging. At temperatures above 400 degrees C, the structure starts decomposing into sodium enneagermanate (Na4Ge9O20), germanium dioxide, and water as determined by powder X-ray diffraction, TGA, DTA, DSC, and GCMS.     

Determination of Germanium in Zinc by Differential Cathode Ray Polarography

Abstract

A differential cathode ray polarographic method is described for determining traces of germanium in zinc and its compounds. The germanium was previously extracted with carbon tetrachloride from the sample solution in hydrochloric acid. After reextraction with water the germanium content was determined polarographically in 1.4 M perchloric acid ? 5.10^?2 M pyrogallol. The detection limit was 0.0012 μg/ml, allowing to detect about 4 ppb of germanium in zinc using 5 g samples.     

Ge4Br4[Mn(CO)5]4 and Ge6Br2[Mn(CO)5]6: first germanium cluster compounds containing Mn(CO)5 ligands

Cluster compounds of germanium exhibiting germanium-germanium bonds, where the germanium atoms are additionally bound to transition metal ligands, are rare. Here a synthetic pathway to such cluster compounds is described, starting from metastable Ge I halide solutions leading to the two cluster compounds Ge4Br4[Mn(CO)5]4 and Ge6Br2[Mn(CO)5]6, being the first examples of germanium cluster compounds bearing Mn(CO)5 ligands. The Ge6 compound exhibits a novel arrangement of germanium atoms that has not been previously observed in ligand stabilized cluster compounds of germanium, neither with organic nor with transition metal ligands. The bonding situation inside the cluster compounds is discussed, together with a possible reaction pathway that opens the way to metalloid cluster compounds of germanium exhibiting Mn(CO)5 ligands.     

三苯基锗不饱和烃基酸衍生物的合成和性质

随着倍半锗氧类化合物的合成及应用研究的日益广泛 ,含 Ge_ O键的烃基锗衍生物的合成及应用也逐渐引起了人们的关注 .1 984年 ,L ukevics等 [1]合成了具有抗癌活性的介吗川类化合物 ,1 990年Kakimoto等 [2 ] 报道了具有杀菌活性的环状烃基羧酸的合成与应用 .但是三烃基锗的膦酸类衍生物的合成及生物活性研究均未见文献报道 .为了研究该类化合物的生理活性 [3～ 5] ,本文以三苯基氯化锗和炔基 (烯基 )膦酸钠为原料 ,在苯中反应 ,合成了一系列双 - O- (三苯基锗 )炔基 (烯基 )膦酸酯和单 - O-三苯基锗炔基 (烯基 )膦酸 ,部分化合物初步生理…     

三苯基锗不饱和烃基膦酸衍生物的合成和性质

随着倍半锗氧类化合物的合成及应用研究的日益广泛,含Ge_O键的烃基锗衍生物的合成及应用也逐渐引起了人们的关注.1984年,Lukevics等[1]合成了具有抗癌活性的介吗川类化合物,1990年Kakimoto等[2]报道了具有杀菌活性的环状烃基羧酸的合成与应用.     

A Multiply Functionalized Base‐Coordinated GeII Compound and Its Reversible Dimerization to the Digermene

Stable compounds with a Ge?Ge bond are usually prepared under relatively harsh reaction conditions that are incompatible with many functional groups. In particular, unsaturated functionalities are not tolerated owing to their facile reaction with low‐coordinate germanium compounds. We now report the synthesis of an imino‐functionalized germanium(II) species, stabilized by coordination of an N‐heterocyclic carbene (NHC), by reaction of an isonitrile with a heavier NHC‐coordinated vinylidene. Removal of the NHC by a Lewis acid results in dimerization to the corresponding digermene with a Ge?Ge bond. The reversibility of this process is demonstrated by addition of two equivalents of NHC to the isolated digermene.     

Luminol Chemiluminescence with Heteropoly Acids and its Application to the Determination of Arsenate,Germanate, Phosphate and Silicate by Ion Chromatography

A flow-injection chemiluminescence (CL) method has been proposed for sensitive determination of arsenate, germanate, phosphate and silicate, after separation by ion chromatography (IC). The post-column detection system involved formation of heteropoly acid in a H₂SO₄ medium before the CL reaction with luminol in an NaOH medium. For separation, heteropoly acid formation and the CL detection reaction, pH requirements were not compatible. When present as a heteropoly acid complex with molybdenum(VI), ger- manium(IV) and silicon(IV) caused CL emission from oxidation of luminol, and such a CL oxidation of luminol was observed analogously for arsenic(V) and phosphorus(V) but with the addition of metavanadate ion to the acid solution of molybdate. Good sensitivity for the three analytes arsenic(V), ger- manium(IV) and phosphorus(V) could be given by a single set of reagent conditions, chosen carefully. Another set was suitable for determining phosphorus(V) and silicon(IV). The minimum detectable concentrations of arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were 10, 50, 1 and 10 μg l⁻¹, respectively. Linear calibrations for arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were established over the respective concentration ranges of 10–1000, 50–25000, 1–1000 and 50–1 μg l⁻¹. The proposed IC–CL method was successfully applied to analyses of a seaweed reference material, rice wine and water samples.     

三氯锗取代丙酰氢化噻唑-2-硫酮类化合物及其水解产物的合成

某些有机锗化物,例如β-羧乙基锗倍半氧化物及其衍生物能诱发干扰素,对癌症有一定疗效,日本专利报道丙酰胺基锗倍半氧化物及其衍生物也具有抗癌活性^[2,3],白明章等曾合成丙酰芳胺基锗倍半氧化物^[4]。     

Reduction of interferences in the determination of germanium by hydride generation and atomic emission spectrometry

Effects of interferences and methods for the reduction of interferences in the determination of germanium were studied. Simultaneous signal enhancement and reduction of interference were achieved using l-cysteine, l-cystine, penicillamine and thioglycerol. Amino acids such as glycine and alanine showed some capacity to reduce interferences, but this was both different in mechanism from, and inferior to, the reagents mentioned above. Histidine, on the other hand, proved to be superior to l-cysteine in its ability to reduce interferences from high levels of nickel. Sodium citrate, sodium oxalate, thiourea and thiosemicarbazide also reduced interferences to some extent. Mechanisms are proposed to explain reduction of interferences and enhancement of signals by the thiol-containing compounds and to explain the behaviour of amino acids as interference-reducing reagents.     

Reactivity of <Emphasis Type="Italic">N</Emphasis>-(chlorodimethylgermyl)methyl and <Emphasis Type="Italic">N</Emphasis>-(chlorodimethylsilyl)methyl derivatives of lactams and amides toward Grignard reagents

N-[(Chlorodimethylgermyl)methyl]lactams and -amides containing a five-coordinate germanium atom react with Grignard reagents chemoselectively by the Ge-Cl bond to form four-coordinate germanium compounds. The method of competitive reactions was used to establish that respective five-coordinate germanium and silicon compounds are almost equally reactive toward Grignard reagents but much more reactive than model four-coordinate germanium and silicon compounds.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 9, 2004, pp. 1462–1465.Original Russian Text Copyright © 2004 by Bylikin, Shipov, Kramarova, Artamkina, Negrebetskii, Baukov.This revised version was published online in April 2005 with a corrected cover date.     

Germania nanoparticles and nanocrystals at room temperature in water and aqueous lysine sols

Facile synthesis of nanometer-sized germania crystals and amorphous germania nanoparticles (ca. 1 nm) is investigated through hydrolysis of germanium tetraethoxide and subsequent condensation of germania in both pure water and aqueous lysine solutions. Germanium tetraethoxide rapidly hydrolyzes in pure water, leading to solvated germanate species at lower germania concentrations and the onset of nanometer-sized germania crystals at room temperature with increasing germania content. In the presence of the basic amino acid L-lysine, amorphous germania nanoparticles (ca. 1 nm) spontaneously form with increasing germania content and coexist with nanometer-sized germania crystals at higher germania concentrations. Lysine and germania concentration both influence crystallite size and morphology (i.e., polyhedral, cubic). The facile, room-temperature crystallization of germania in the presence and absence of lysine is striking. The fact that the crystal morphology shows no signs of nanoparticle aggregative assembly, as has been observed in the formation of other oxide crystals, suggests that crystal growth takes place by addition of dissolved species rather than nanoparticles, and could have implications for other oxide systems.     

Ge8R6: the ligands define the bonding situation within the cluster core

The disproportionation reaction of Ge(i) halides open up a way to cluster compounds with an average oxidation state of the germanium atoms inside the cluster core in between 0 and 1. Simultaneously compounds with germanium in an oxidation state greater than i are formed. During the reaction of Ge(i) bromide with one equivalent of LiR (R = 2,6-(tBuO)(2)C(6)H(3)) the cluster compound Ge(8)R(6) and the molecular Ge(iv) compound R(3)GeBr were isolated, representing the reduction and the oxidation product of the disproportionation reaction, respectively. The molecular structure of the Ge(8) cluster compound shows a highly different arrangement of the eight germanium atoms in the cluster core with respect to the only other Ge(8)R(6) cluster compound where amido ligands are bound to the germanium atoms. Quantum-chemical calculations reveal that the distinct arrangement of the germanium atoms can be traced back to a different bonding situation inside the cluster frameworks, which is induced by the different ligands attached to the germanium atoms. These experimental and theoretical results show that the ligands are not only necessary for protecting the cluster core against the exterior but also have a strong influence on the bonding situation and therefore on the electronic situation inside the cluster core. Hence, the ligand influences the electronic properties and consequently the physical properties which is now seen, for the first time, in metalloid germanium cluster compounds.     

Synthesis of Five Coordinate Spirocyclic Germanium(IV) Complexes Containing Diethanol Amine

Reaction of dihydroxo(2,2′-iminodiethanolato-AWO′) germanium(IV) (A) or dihydroxo(2,2′-methyliminodiethanolato-N,O.O′) germanium(IV) (B) with bidentate ligands, e.g. diol, α-hydroxy acid, oxalic acid, 2,6-pyridinedicarboxylic acid, or 2-aminophenol in a mixture of ethanol and xylene mixture yielded a series of unsymmetrical spiro-germanium complexes 1-6. These complexes were characterized by NMR, IR, mass spectra and elementary analysis. The ¹H NMR spectrums of all these compounds show the existence of an intramolecular N – Ge bond. X-ray analysis of compound 6 shows a short N–Ge bond (2.08 Å).