Germanium Analogues Research Articles

Heterocyclic systems containing tin(IV)—XIII [1]. Possible ceasing or inversion of the structural trans influence during the course of a bimolecular nucleophilic attack of a donor group in a series of Sn IV rings

In the series of the heterocycles X[(CH 2) 3] 2SnR 2 (16 newly synthesized compounds and two taken from the literature) and in the germanium analog Bu i N[(CH 2) 3] 2GeCl 2, the donor group X (= NMe, NBz, NBu i , NPr i , O, S) intramolecularly attacks the Lewis acidic atoms Sn or Ge. Eight structure determinations (and, in addition, 2 taken from the literature) are compared. The nucleophilic attack at Sn is stronger for the ligands R 2 =Cl 2 than for the more electronegative R 2 = (OSiPh 3) 2. Overall the familiar trans influence holds: simultaneous approach of X and weakening of the ligand R ( trans). In three cases of subtly graded donor strength a slight inversion or ceasing is observed: shorter distances X/3.Sn and simultaneously shorter distances Sn R( trans). Also in a series of 8 compounds with O/3.Si (Hal) interaction, taken from the literature, the dominant trans influence ceases to zero in the central part of the oxygen approach. Actually, the discussed ranges of inversion or ceasing of the trans influence are small and in terms of e.s.d.s at the borderline of statistical significance. Despite this objection, the existence of four alike cases is noticeable. As an explanation for this secondary effect, a bonding scheme is discussed in which the electronegativity of the ligands inhibits the nucleophilic attack and in which its drive originates from the π-basicity of the ligands into a σ *-LUMO at Sn or Ge. This bonding scheme is supported by semi-empirical MO calculations on the extended Hückel level for the Ge compound and its tetrahedral analogue Cl 2GeBu 2 n . In addition, a qualitative discussion of 119Sn NMR chemical shifts is given, which uses the same line of arguments as applied above on the basis of interactions of frontier orbitals.

Formation and oxidation reaction of polychalcogenadisilabicyclo[k.l.m.]alkanes and their germanium analogues

Polychalcogenadisilabicyclo[k.l.m]alkanes and their germanium analogues were systematically synthesized by the reaction of tris(trimethylsilyl)methylsilane (TsiSiH 3) or tris(trimethylsilyl)methylgermane with elemental sulfur or selenium. Structures of the resulting bicyclo[k.l.m]alkanes were confirmed by X-ray diffraction analysis or 77Se NMR spectroscopy. Oxidation of polythia-1,3-disilabicyclo-[k.l.m]alkanes with a peracid afforded the corresponding ring expansion products.

Strontium Metasilicate, SrSiO3

Strontium silicon trioxide has been synthesized for the first time and its structure solved. It is isostructural with the germanium analogue SrGeO3 reported by Hilmer [Sov. Phys. Crystallogr. (1963). 7, 573–576], but the true symmetry is monoclinic, rather than hexagonal as reported earlier. The structure has alternate layers of ternary rings of SiO4 groups and close-packed Sr atoms stacked along [001]. Viewed as a polytype, this compound has a six-layer structure and the calcium analogue, α-CaSiO3 [Yamanaka & Mori (1981). Acta Cryst. B37, 1010–1017] has a four-layer structure.

Synthesis, Structures and Reactions of Polychalcogenadisilabicyclo[l.m.n]alkanes and Their Germanium Analogues

Synthesis, Structures and Reactions of Polychalcogenadisilabicyclo[l.m.n]alkanes and Their Germanium Analogues

Synthesis, Structures and Reactions of Polychalcogenadisilabicyclo[l.m.n]alkanes and Their Germanium Analogues

1,3-Bis[tris(trimethylsilyl)methyl]-2,4,5-trichalcogena-1,3-disilabicyclo[1.1.1]pentanes display unusual short bridgehead Si---Si distances despite the absence of formal Si—Si bonds, and chalcogen---chalcogen interactions are observed by nmr, X-ray analysis and electronic spectroscopy.

Ultrasonic activation of SiO 2 and GeO 2 in basic solutions of diols

The sonication of silica gel in basic solutions of diols causes rapid breakdown of the inorganic polymer and the formation of monomeric silicon complexes. The triscatecholate complex Na 2[(C 6H 4O 2) 3Si] is formed cleanly and in good yield at room temperature. The germanium analogue Li 2[(C 6H 4O 2) 3Ge] may be formed similarly from GeO 2 but TiO 2 remains unaffected by ultrasound.

A Computational Study of the Energetics and Lattice Dynamics of Germanium Containing Zeolitic Solids

Lattice energy minimization techniques have been used to predict the stability of germanium analogues of common zeolite structures. The calculations suggest that complete solid solutions may occur for SiO 2 and GeO 2 in the quartz, mordenite, silicalite-I, and zeolite-Y structures, with only small deviations from ideality and lattice parameter variations consistent with Vegard's law. Nonrandom distributions of Si and Ge over tetrahedral (T) sites, however, lead to deviations from the predicted linearity of the variations of the lattice parameter with composition. Calculated infrared spectra are also presented for the four structures with varying Si:Ge ratios. Again, it is predicted that with nonrandom Si/Ge distributions, there are substantial changes in the calculated vibrational spectra.

Group 14 metalated 6-amino-1-azafulvene dimers. Evidence for a double intramolecular nitrogen-tin interaction

The structures of group 14 C-metalated 6-amino-1-azafulvene dimers have been investigated in solution and in the solid state by NMR spectroscopy. For one of these compounds, 5,10-bis(dimethylamino)-3,8-bis(trimethylstannyl)-5H,10H-dipyrrolo[1,2-a: 1',2'-d]-pyrazine (2c), the molecular structure in the solid state has been determined by X-ray diffractometry. The two tin centers have a distorted-trigonal-bipyramidal co-ordination geometry with the more electronegative N ligand at a pseudoaxial position, resulting in one of the longest known Sn - N interactions: 3.101 (5) A°. Moreover, the temperature-dependent 13C CP-MAS NMR spectrum of this compound shows an appreciable narrowing of the Me3Sn signal between 296 and 333 K. By comparison with nonmetalated analogs or with isomer 5c, the nonreactivity of compound 2c toward hydrolytic decomposition into corresponding 5-(trimethylstannyl)-pyrrole-2-carbaldehyde (3c) may be the result of stabilization of the dimeric form 2c by a double Sn - N interaction. In silicon and germanium analogs (2a, 2b) the Si(Ge) - N interaction is weaker.

Bis(4-fluorophenyl)methyl(1 H-1,2,4-triazol-1-yl-methyl)-germane, a germanium analogue of the agricultural fungicide flusilazole: Synthesis and biol

Bis(4-fluorophenyl)methyl(1 H-1,2,4-triazol-1-yl-methyl)germane ( 2), a germanium analogue of the agricultural fungicide flusilazole ( 1), has been synthesized from Cl 3GeCH 2Cl ( 3) by both a three-step and a four-step synthesis ( 3 → ( p-F-C 6H 4) 2Ge(CH 2Cl)Br ( 4) → ( p-F-C 6H 4) 2Ge (CH 2Cl)CH 3 ( 5) → 2; 5 → ( p-F-C 6H 4) 2Ge(CH 2I)CH 3 ( 6) → 2). The fungicidal properties of 2 have been compared with those of the parent silicon compound 1 (studies on Si/Ge bioisosterism). In various test systems, the Si/Ge analogues 1 and 2 showed comparable fungicidal properties (in activity against plant pathogenic fungi: in ag

Generation, low-temperature stabilization, structure, and reactivity of intermediates with low-coordinated carbon, silicon, and germanium atoms

The mechanisms of thermal and photochemical transformations of organic and organometallic compounds which pass through formation of different reactive intermediates were investigated by low-temperature matrix IR spectroscopy. Low-temperature matrix stabilization of the intermediates, the primary products of these reactions, was conducted at 10–15 K. The spectral and structural parameters of the free radicals (CCl3, CCl2Br, CClBr2, CH2CH=CH2, CF2CF=CF2, CH2-C≡CH, CH2C≡N, CH2Ph, CF2C6F5), halocarbenes and their silicon and germanium analogs, and unstable molecules with double-bond silicon and germanium atoms were obtained as a result.

Generation, low-temperature stabilization, structure and reactivity of intermediates with low-coordinated carbon, silicon and germanium atoms

Abstract

15N CPMAS NMR Study of th Structure and Reactions of Phthalocyaninatopolysiloxane and its Precursors in the Solid State

Communication: The high conductivities of the iodine doped title compound (see figure) and its germanium analogue have attracted considerable interest. Structural analysis by X‐ray crystallography has not been possible, and solid state 13C NMR has yielded complex spectra which are often difficult to assign. 15N CPMAS NMR spectroscopy of 15N enriched samples provides a powerful tool for the study of the structure and reactivity of these species. magnified image

Laser photolysis of aryl-substituted digermanes. Generation of germyl radicals and germylenes

The photochemistry of organosilicon compounds having a /sigma/(Si-Si)-/pi/(C-C) conjugated system has been the subject of considerable interest in recent years. However, there have been few reports on photochemical studies of the germanium analogue. The authors describe herein the first laser photolysis studies on the aryl-substituted digermanes (Ph/sub n/Me/sub 3-n/Ge)/sub 2/ (1-3, n = 1-3, respectively). Photolysis of the phenylated digermanes causes germanium-germanium bond homolysis which leads to the formation of a germyl radical and probably a germylene.

ChemInform Abstract: The Synthesis and Some Applications of New 1,3‐Dilithiopropanes: Dimethylbis(α‐lithiobenzyl)silane and Its Germanium Analogue.

AbstractBenzyl bromide (I) is converted into the thioether (III) and then lithiated.

The synthesis and some applications of new 1,3-dilithiopropanes: dimethylbis(α-lithiobenzyl)silane and its germanium analogue

The dimethylbis(α-lithiobenzyl)silanes and -germanes were prepared by the reaction of dimethylbis(α-thiophenylbenzyl)silane or -germane with lithium dispersion and their reactions with Me 3M′Cl (M = Ge, Sn) investigated. The lithium compounds proved to be useful in the synthesis of 2,4-diphenyl-substituted 1,3-disila-, 1,3-digerma- and 1-germa-3-silacyclobutanes.

Enantioselective reduction of acetyldimethylphenylsilane by Trigonopsis variabilis (DSM 70714)

Growing and resting cells of the yeast Trigonopsis variabilis (DSM 70714) can be used for the enantioselective reduction of the organosilicon compound acetyldimethylphenylsilane (1) to give optically active (R)-(1-hydroxyethyl)dimethylphenylsilane [(R)-2] in good yields. The enantiomeric purity of the isolated product was determined to be 62–86% ee depending on the substrate concentration used. Both substrate and product caused an inhibition of the reaction at concentrations higher than 0.35 and 0.5 g/l, respectively. Besides, higher substrate and product concentrations led to increased formation of the by-product 1,1,3,3-tetramethyl-1,3-diphenyldisiloxane. Considering the limiting substrate and product concentrations, it was possible to use the same biomass at least 5 times without significant loss of enzyme activity. 3-Methyl-3-phenyl-2-butanone (5) and acetyldimethylphenylgermane (7), which represent carbon and germanium analogues of 1, were also found to be accepted as substrates by Trigonopsis variabilis (DSM 70714). The reduction rates of the silicon (1) and germanium compound (7) were much higher than the transformation rate of the corresponding carbon analogue 5.

Carbene complexes: XX. Electron-rich carbeneiron(0) trigonal bipyramidal carbonyls and their germanium(II) and tin(II) analogues [Fe(CO)3(L)(L′)] (L = [formula omitted]Me, L′ = PEt3, 3 CO's equatorial; or L = M(OAr)2 (equatorial: M = Ge OR Sn, Ar = C6H2But2-2,6-Me-4), L′ = CO)

The first bis(aryloxo)-main Group 14 metal(II)-transition-metal complexes eq-[Fe(CO)4){M(OAr)2}] (eq- denotes equatorial, Ar = C6H2But2-2,6-Me-4, and M = Ge (II) or Sn (III)) have been prepared, from [Fe2(CO)9] and the appropriate aryloxide M(OAr)2. X-ray structures of the complexes II and III show them to have the unusual (for a trigonal bipyramidal (tbp) [Fe(CO)4L] complex) eq-distorted tbp configuration. The related carbene complex [Fe(CO)3(LMe)(PEt3)] (I) [LMe = CN(Me)(CH2)2NMe] has the tbp-rans-configuration in the crystal. The stereochemical integrity of each of I–III is maintained in solution. The exceptionally short Fe-Ge and Fe-Sn distances, and the relatively small deviation from coplanarity of the MO2 plane and the Fe(CO)axM planes are consistent with the ligands M(OAr)2 being good π-acceptors but poor σ-donors in complexes II or III. By contrast, the X-ray data for complex I support the view the LMe is a strong σ-donor but weak π-acceptor. For a series of tbp-trans-[Fe(CO)3(L)(L′)] complexes, a comparison of Fe-Ccarb and Fe-P distances shows that the trans-influence of a ligand L falls in the sequence L = CO ρ PR3 ρ LMe.

Subvalent Group 4B metal alkyls and amides. Part 8. Germanium and tin carbene analogues MR2[M = Ge or Sn, R = CH(SiMe3)2]: syntheses and structures in the gas phase (electron diffraction); molecular-orbital calculations for MH2 and GeMe2

Bis[bis(trimethylsilyl)methyl]germanium, GeR2[R = CH(SiMe3)2], is conveniently prepared from GeCl2(diox)(diox = 1,4-dioxane)(for which an improved synthesis, from GeCl4 and SnHBun3, is reported) and 2MgCl(R)(OEt2), MgR2(diox)0.5, or MgR2(OEt2) in OEt2. The corresponding tin(II) alkyl is accessible from SnCl4 and successively 2LiR (to yield SnCl2R2) and Li2(cot)(cot = cyclooctatetraene) in OEt2. Gas-phase electron diffraction (g.e.d.) patterns, recorded with nozzle temperatures of 155 °C for GeR2 and 120 °C for SnR2, show that the gas consists of V-shaped monomers. Least-squares refinements of models of C2 symmetry yielded the bond distances Ge–C 203.8(15) and Sn–C 222(2) pm and the angles CGeC 107(2) and CSnC 97(2)°. In GeR2 the –CH(SiMe3)2 ligands are oriented so that the HCiMCiH moiety (Ci= inner, or methine, C) has a nearly planar syn,syn conformation but in SnR2 the dihedral angles CiMCiH are ca. 15°. Ab initio molecular-orbital calculations with a better than DZ (double zeta) basis were carried out on the model compounds MH2 and GeMe2, and yielded the optimal bond distances Ge–H 158, Ge–C 202, and Sn–H 177 pm, and valence angles HGeH 93, CGeC 97, and HSnH 93°. Correlation of experimental and calculated structures shows that MII–H and MII–C bond distances are significantly larger (by 4–10 pm) than their MIV–H and MIV–C counterparts, and valence angles at M increase in the series GeH2= SnH2 < GeMe2= SnMe2 < GeR2 < SnR2. Both the long bond distances and the less-than-tetrahedral valence angles are rationalised by assuming the metal lone pair to occupy atomic orbitals of predominant s character and the M–H and M–C σ-bonding orbitals to be formed from metal atomic orbitals of predominant p character.

A comparison of garnet-ilmenite-perovskite phase equilibria in germanate and silicate systems at high pressures

Phase equilibria have been investigated in the system CaGeO 3MgGeO 2Al 2O 3 and on germanium analogues of basalt and a pyrolite-related system at pressures between 2 and 11 GPa and at temperatures between 850 and 1200°C. Solid solubility relationships between garnet, ilmenite and perovskite-type phases were determined and compared with those in the corresponding silicate systems. There are some interesting similarities where the germanate equilibria are able to provide insight into the phase chemistry of corresponding silicate systems. However, there are also some significant differences that limit the ability of germanate models to predict the probable behaviour of corresponding silicate systems at higher pressures.

Structures of sodium alumino- and gallosilicate glasses and their germanium analogs

Polarized Raman spectra of SiO 2 and GeO 2 glasses are related on the basis of frequencies, band-shapes, and polarization characteristics. The spectra are consistent with structures composed of continuous networks of SiO 4 and GeO 4 tetrahedra. The presence of depolarized TO and LO components of the antisymmetric stretching mode in the high frequency region of both spectra indicates that these single component glasses retain some degree of intermediate range order. Features in the polarized spectra of NaAlSi 3O 8, NaAlSi 2O 6, and NaAlSiO 4 glasses and their Ga- (for Al) and/or Ge- (for Si) substituted counterparts are also consistent with the assignment of three-dimensional tetrahedral framework (TDTF) structures to these glasses. The gallosilicate and alumino- and gallogermanate glasses provide structural analogs for the framework aluminosilicate glasses of geological significance. The high-frequency antisymmetric stretching features in the Raman spectra of the TDTF aluminosilicate glasses and their Ga- and/or Ge-substituted analogs show an overlapping doublet of bands whose frequencies vary continuously with glass composition. Both the intensity and position of the higher frequency component are more strongly dependent on Al(Ga) content than is the lower frequency component. Some coupling of the antisymmetric stretching modes of Si(Ge)O 4 tetrahedra and Al(Ga)O 4 tetrahedra is indicated. The higher frequency component of the doublet is more strongly polarized than the lower frequency component, which results from the splitting of the antisymmetric stretching (F) mode of Si(Ge)O 4 tetrahedra. This splitting results from the lowering of the average of Si(Ge)O 4 tetrahedra site symmetries because of the presence of Al(Ga)O 4 units in the glass network.