Molekulares SSi(H)CI Matrix-IR-Untersuchungen und ab- initio SCF-Rechnungen

The Molecule S?Si(H)CI. Matrix IR Investigation and Initio SCF Calculation Molecular S?Si(H)CI is formed in an argon matrix after the Photochemically induced reaction of SiS with HCI. From the isotopic splittings (H/D and ³⁵,CI/³⁷CI) of the IR absorptions the C_s-structure of the species with silicon as the central atom can be deduced. By an normal coordinate analysis a value of 4.83 mdyn/Å is obtained for the SiS force constant. These experimental results are confirmed by ab initio SCF calculations of the IR spectrum.     

Crystal structure of germanium(II) dichloride solvated by tetrahydrofuran

The thermally highly unstable tetrahydrofuran solvate of germanium(II) dichloride (GeCl₂ · 2THF) was crystallized, and its crystal structure was determined. It consists of a chain of GeCl₂ units connected by secondary Cl···Ge contacts [3.846(2) Å] in which each Ge atom is coordinated to two molecules of THF. Two weak hydrogen bonds of the C H ··· Cl Ge type in GeCl₂ · 2THF were also detected both with lengths of 2.90(3) Å. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:361–363, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20105     

Halometallates of 1-methyl-4,4-dimercapto-piperidinium. Evidence of strong hydrogen bonds with participating thiol groups

Chlorometallates of transition and B subgroup elements are readily prepared and precipitated by reaction of the corresponding metallic salts with 1-methyl-4,4-dimercaptopiperidinium chloride. These chlorometallates investigated were [ZnCl₄]^2?, [CdCl₃]^?, [CoCl₄]^2?, [CuCl₅]^3? and [FeCl₄]^2?. Strong SH … Cl interactions, but not NH … Cl, have been evidenced by IR spectroscopy in the zinc, cadmium and cobalt complexes. The SH and NH absorptions are observed at ? 2480 cm^?1 and 3060 cm^?1, respectively. Partial deuteration of the [ZnCl₄]^2? complex with d₁-methanol, shifted these IR signals to 1800 and 2260 cm^?1, clearly evidencing a X-hydrogen type of bond. The SH … Cl interaction is smaller in the [FeCl₄]^2? complex, and practically nonexistent in the [CuCl₅^3? complex.     

Molekulares PO2Br Matrix-IR-Untersuchung und ab initio SCF-Rechnungen

Molecular PO₂Br. Matrix IR Investigations and ab initio SCF Calculations Monomeric PO₂Br produced by a photochemical reaction between the high-temperature molecule OPBr and O₃ in solid Ar has been studied by IR spectroscopy. IR spectra including ¹⁶O/¹⁵O-shifts of the planar molecule with C_2v symmetry show that the OPO angle is about 135° and that the PBr bond is unexpectedly strong (f(PBr) = 2.8 mdyn/Å). These results are confirmed by ab initio SCF calculations.     

Ab initio calculations of complexes of group IVA tetrachlorides: VI. Structure and dynamics of formation of a complex of GeCl<Subscript>4</Subscript> with tetramethylurea

RHF/6-31G(d) calculations of the GeCl₄←OC[N(CH₃)₂]₂ system were done with full geometry optimization and at varied Ge←O distances. The calculated structure of the complex GeCl₄←OC[N(CH₃)₂]₂ and its ³⁵Cl NQR parameters were consistent with the experimental data not at the fully optimized geometry of the system but at the Ge←O distance fixed at 2.0 Å, at which the total energy of the system is higher by 0.264 eV. With a decrease in the Ge←O distance from ∞ to 1.9 Å, the electron density of the Cl atoms increases as a result of the electron density transfer from the H atoms and polarization of the Ge-Cl bonds under the action of the electron-donor fragment. The O, C, and N atoms of this fragment are merely conductors of the electron density from the H atoms of the methyl groups to the Cl atoms of the electron acceptor.     

Nickel as a Lewis Base in a T‐Shaped Nickel(0) Germylene Complex Incorporating a Flexible Bis(NHC) Ligand

Flexible, chelating bis(NHC) ligand 2 , able to accommodate both cis‐ and trans‐coordination modes, was used to synthesize ( 2 )Ni(η²‐cod), 3 . In reaction with GeCl₂, it produced ( 2 )NiGeCl₂, 4 , featuring a T‐shaped Ni⁰ and a pyramidal Ge center. Complex 4 could also be prepared from [( 2 )GeCl]Cl, 5 , and Ni(cod)₂, in a reaction that formally involved Ni–Ge transmetalation, followed by coordination of the extruded GeCl₂ moiety to Ni. A computational analysis showed that 4 possesses considerable multiconfigurational character and the Ni→Ge bond is formed through σ‐donation from the Ni 4s, 4p, and 3d orbitals to Ge. (NHC)₂Ni(cod) complexes 9 and 10 , as well as (NHC)₂GeCl₂ derivative 11 , incorporating ligands that cannot accommodate a wide bite angle, failed to produce isolable Ni–Ge complexes. The isolation of ( 2 )Ni(η²‐Py), 12 , provides further evidence for the reluctance of the ( 2 )Ni⁰ fragment to act as a σ‐Lewis acid.     

AB initio SCF LCAO MO study of the HOH…Cl− hydrogen bond

Ab initio SCF LCAO MO calculations for the [H₂O…Cl]^? complex have been performed. The energy of the linear hydrogen bond has been found to be lower than the energy of the bifurcated one. The difference of the energies is about 3 kcal/mole. The calculated equilibrium distance between the oxygen and chlorine atoms equals 5.75 au. The interaction energy of the chlorine anion and the rigid water molecule amounts to ?19 kcal/mole. The optimization of the OH bond length in the complex (linear hydrogen bond) leads to an interaction energy of ?19.5 kcal/mole (the experimental value equals ?13.1 kcal/mole). As a result of the hydrogen bond formation the OH bond length increases by 0.08 au.     

Ab initio Study of Anharmonic Force Field and Spectroscopic Constants for Germanium Dichloride

Ab initio study of the equilibrium structure, spectroscopy constants, and anharmonic force field for several isotopomers of germanium dichloride (⁷⁰GeCl₂, ⁷²GeCl₂, and ⁷⁶GeCl₂) have been carried out at the MP2 and CCSD(T) levels of theory using cc-pVTZ basis set. The calculated geometries, rotational constants, vibration-rotation interaction constants, harmonic frequencies, anharmonic constants, quartic and sextic centrifugal distortion constants, cubic and quartic force constants are compared with experimental data. For small mass differences of the Ge isotopes, the isotopic effects for germanium dichloride are much weaker. The agreements are satisfactory for these two methods, but the deviations of CCSD(T) results are slightly larger than that of MP2, because of CCSD(T)'s inadequate treatment of electron correlation in hypervalent Cl atom.     

A Bis(silylenyl)pyridine Zero‐Valent Germanium Complex and Its Remarkable Reactivity

The synthesis, reactivity, and electronic structure of the unique germylone iron carbonyl complex [SiNSi]Ge⁰ →Fe(CO)₄ is reported. The compound was obtained in 49 % yield from the reaction of the bis(N‐heterocyclic silylenyl)pyridine pincer ligand SiNSi (1,6‐C₅NH₃‐[EtNSi(N^tBu)₂CPh]₂) with GeCl₂?(dioxane) to give the corresponding chlorogermyliumylidene chloride precursor [SiNSi]Ge^IICl⁺ Cl^? , which was further reduced with K₂Fe(CO)₄. Single‐crystal X‐ray diffraction analysis of [SiNSi]Ge →Fe(CO)₄ revealed that the Ge⁰ center adopts a trigonal‐pyramidal geometry with a Si‐Ge‐Si angle of 95.66(2)°. Remarkably, one of the Si^II donor atoms in the complex is five‐coordinated because of additional (pyridine)N→Si coordination. Unexpectedly, the reaction of [SiNSi]Ge →Fe(CO)₄ with GeCl₂?(dioxane) (one molar equivalent) yielded the first push–pull germylone–germylene donor–acceptor complex, [SiNSi]Ge →GeCl₂→Fe(CO)₄ through the insertion of GeCl₂ into the dative Ge⁰→Fe bond. The electronic features of the new compounds were investigated by DFT calculations.     

Reactions of GeCl2 with the Thiolate LiSC(SiMe3)3: From thf Activation to Insertion of GeCl2 Molecules into C−S Bonds

The reaction system GeCl₂ ⋅ dioxane/LiSTsi (Tsi=C(SiMe₃)₃) opens a fruitful area in germanium chemistry, depending on the stoichiometry and solvent used during the reaction. For example, the reaction of GeCl₂ ⋅ dioxane in toluene with two equivalents of the thiolate gives the expected germylene Ge(STsi)₂ in excellent yield. This germylene readily reacts with hydrogen and acetylene, however, in a non-selective way. By using an excess amount of the thiolate and toluene as the solvent, the germanide [Ge(STsi)₃][Li(thf)] is obtained. Performing the same reaction in thf leads to a C−H activation of thf to give (H₇C₄O)Ge[STsi](μ²-S)₂Ge[STsi]₂, in which the thf molecule is still intact. Using a sub-stoichiometric amount of the thiolate leads to the heteroleptic compound [ClGe(STsi)]₂ and to the insertion product (thf)Ge[S-GeCl₂-Tsi]₂, in which additional GeCl₂ molecules insert into the C−S bonds of Ge(STsi)₂. The synthesis and the experimentally determined structures of all compounds are presented together with first reactivity studies of Ge(STsi)₂.     

High-spin Mangan(II)-Phthalocyanine: Darstellung und spektroskopische Eigenschaften von Acidophthalocyaninatomanganat(II)

High Spin Manganese(II) Phthalocyanines: Preparation and Spectroscopical Properties of Acidophthalocyaninatomanganate(II) Acidophthalocyaninatomanaganese(III) is reduced by boranate, thioacetate or hydrogensulfide to yield acidophthalo-cyaninatomanganate(II) ([Mn(X)Pc^2?]^?; X = Cl, Br, NCO, NCS) being isolated as tetra(n-butyl)ammonium salt. In the cyclovoltammogram of [Mn(NCO)Pc^2?]^? the halv-wave potential for the redoxcouple Mn^II/Mn^III is at ?0.13 V, that of the first ring reduction at ?0.99 V. The magnetic moments are indicative of high-spin ⁶A₁ ground states: μ_Mn = 5.84 (NCO), 5.78(Cl), 5.65 (Br), 5.68 μ_B (NCS). A Curie-like temperature dependence of μ_Mn is observed in the region 300–30 K. Below 30 K an increase in μ_Mn occurs due to weak intermolecular ferromagnetic coupling. The ESR spectra confirm the S = 5/2 ground state with a strong g = 6 resonance observed (A_Mn = 80 G) as expected for an axially distorted ligand-field. Besides the typical π-π* transitions of the Pc^2?-ligand several weak bands are observed in the Uv-vis-n.i.r. spectra at ca. 7.5, 9.1, 14.0 and 19.0 kK that are assigned to trip-multiplet transitions. In resonance with the band at 19.0 kK the Mn? X stretching vibration (v(MnX)) is resonance Raman enhanced: X = NCO: 319, Cl: 286, SCN: 238, Br: 202 cm^?1. These vibrational frequencies are confirmed by the f.i.r. spectra. In the case of the thiocyanato-complex probably both forms of bonding of the ambident NCS-ligand are present (v(Mn? NCS): 274 cm^?1). The frequencies of the vibrations of the inner (CN)₈ ring are reduced by up to 20 cm^?1 as compared with those of low spin Mn^II phthalocyanines.     

A relation between 73Ge chemical shifts and CNDO/2 charges in tetrahalogenogermanes

Using Hojer and Meza's extension of the CNDO/2 method to third row elements, a linear relationship is established between the calculated atomic charges on the Ge atom in germanium tetrahalides GeCl_nBr_4-n (n = 0, 1, 2, 3, 4) and their recently measured ⁷³Ge chemical shifts.     

Synthesis and molecular and crystal structures of new cation-anionic hypervalent germanium complexes with 1,1,3,3-tetrakis(O—Ge)chelato-1,1,3,3-tetra(lactamomethyl)-1,3-digermoxane dications

The reaction of dichloride (L⁵)₂GeCl₂ with LiI·H₂O under conditions, which did not exclude exposure to atmospheric oxygen, as well as hydrolysis of chloride triflate (L⁷)₂Ge(Cl)OTf in the presence of Et₃N and of perchlorate (L⁵)₂Ge(Cl)OClO₃ by atmospheric moisture afforded cation-anionic complexes containing the digermoxane dications of the general formula [(L ⁿ )₂GeOGe(L ⁿ )₂]²⁺ (L ⁿ is a lactamomethyl n-membered bidentate C,O-coordinating ligand) with the triiodide, triflate, and perchlorate ions, respectively. According to the results of X-ray diffraction study, the digermoxane dications in these complexes contain two pentacoordinate Ge atoms each and occur as germylium ions stabilized by two OGe coordination bonds. In these complexes, the digermoxane dications are diastereomers in which the bischelate systems have opposite configurations.     

Synthese,Struktur und Eigenschaften von [nacnac]MX3‐Verbindungen (M = Ge,Sn; X = Cl,Br, I)

Synthesis, Structure, and Properties of [nacnac]MX₃ Compounds (M = Ge, Sn; X = Cl, Br, I) Reactions of [nacnac]Li [(2,6‐ⁱPr₂C₆H₃)NC(Me)C(H)C(Me)N(2,6‐ⁱPr₂C₆H₃)]Li ( 1 ) with SnX₄ (X = Cl, Br, I) and GeCl₄ in Et₂O resulted in metallacyclic compounds with different structural moieties. In the [nacnac]SnX₃ compounds (X = Cl 2 , Br 3 , I 4 ) the tin atom is five coordinated and part of a six‐membered ring. The Sn–N‐bond length of 3 is 2.163(4) Å and 2.176(5) Å of 4 . The five coordinated germanium of the [nacnac]GeCl₃ compound 5 shows in addition to the three chlorine atoms further bonds to a carbon and to a nitrogen atom. In contrast to the known compounds with the [nacnac] ligand the afore mentioned reaction creates a carbon–metal‐bond (1.971(3) Å) forming a four‐membered ring. The Ge–N bond length (2.419(2) Å) indicates the formation of a weakly coordinating bond.     

Ab initio calculations of group IVA tetrachloride complexes: VII. Structure and dynamics of the formation of GeCl<Subscript>4</Subscript> complexes with hexamethylphosphoric triamide

Quantum-chemical calculations by the RHF/6-31G(d) method were performed for the systems GeCl₄←[N(CH₃)₂]₃ and GeCl₄←₂OP[N(CH₃)₂]₃ with full geometry optimization and varied Ge←O distances. The calculations with full geometry optimization gave trigonal-pyramidal and trans-octahedral structures, respectively, which agrees with experimental NQR data. As the components of a system get closer together, mutual polarization followed by electron density transfer from H atoms of the electron donor onto Cl atoms of the electron acceptor take place. The O and Ge atoms act as conductors in this electron density transfer. Nonempirical quantum-chemical calculations do not reproduce adequately the p _σ density of the axial Cl atom in the trigonal-bipyramidal complex.     

A Coordination Compound of Ge0 Stabilized by a Diiminopyridine Ligand

Reduction of the cationic Ge^II complex [dimpyrGeCl][GeCl₃] (dimpyr=2,6‐(ArN=CMe)₂NC₅H_3, Ar=2,6‐iPr₂C₆H₃) with potassium graphite in benzene affords an air sensitive, dark green compound of Ge⁰, [dimpyrGe], which is stabilized by a bis(imino)pyridine platform. This compound is the first example of a complex of a zero‐valent Group 14 element that does not contain a carbene or carbenoid ligand. This species has a singlet ground state. DFT studies revealed partial delocalization of one of the Ge lone pairs over the π*(C?N) orbitals of the imines. This delocalization results in a partial multiple‐bond character between the Ge atom and imine nitrogen atoms, a fact supported by the X‐ray crystallography and IR spectroscopy data.     

Geometries,vibrational frequencies,and electron affinities of X2Cl (X=C,Si,Ge) clusters

Ab initio quantum chemical calculations have been performed on X₂Cl^? and X₂Cl (X = C, Si, Ge) clusters. The geometrical structures, vibrational frequencies, electronic properties and dissociation energies are investigated at the Hartree–Fock (HF), Møller–Plesset second‐ and fourth‐order (MP2, MP4), CCSD(T) level with the 6‐311+G(d) basis set. The X₂Cl (X = C, Si, Ge) and X₂Cl^? (X = Si, Ge) take a bent shape obtained at the ground state, while C₂Cl^? has a linear structure. The impact on internal electron transfer between the X₂Cl and the corresponding anional clusters is studied. The three different types of electron affinities (EAs) at the CCSD(T) are reported. The most reliable adiabatic electronic affinities, obtained at the CCSD(T)/cc‐pvqz level of theory, are predicted to be 3.30, 2.62, and 1.98 eV for C₂Cl, Si₂Cl, and Ge₂Cl, respectively. The calculated EAs of C₂Cl and Ge₂Cl are in good agreement with theoretical results reported. The correlation effects and basis sets effects on the geometrical structures and dissociation energies are discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Synthèses et caractérisation de germylènes difonctionnels

Syntheses and caracterization of bifunctional germylenes Several synthetic methods of bifunctional germylenes GeY₂ (Y = RO, PhO, RS, CH₃COO, Acac; Y₂ = OCH₂CH₂O, SCH₂CH₂S) or GeXY (Y = RO, X = Cl; Y = RS, X = Cl; Y = Acac, X = Cl) such as exchange reactions, dechlorhydratation reactions and nucleophilic substitutions from GeCl₂ · dioxane are described. Some more synthesis of divalent species GeY₂ from Ge(OR)₂ by transalcoxylation and from Ge(Cp)₂ by cleavage using protic species will be presented. The stability and reactivity of these germylenes are discussed. Difunctionnal germylenes give generally a selfpolycondensation reactions. However, their reactivity in situ shows a effective participation of monomeric species GeY₂.     

Ab initio calculations including electron correlation,and mindo/3 calculations on the system C2H+7

Ab initio SCF and CEPA PNO calculations have been performed together with MINDO/3 calculations on the system C₂H⁺₇. In agreement with experimental assignment, but in contradiction to MINDO/3 results, the ab initio methods show the CC protonated structure to be more stable than the CH protonated structure. The energy difference is 8.5 kcal/mol at the SCF level and 6.3 kcal/mol with inclusion of electron correlation. Additionally, ΔH⁰₃₀₀ for the reaction C₂H⁺_s + H₂ = C₂H⁺₇ and the proton affinity of ethane are computed.     

On the tri-n-octylammonium chloro complexes of Cu(II), Zn(II) and Co(II) in benzene solution

Extracts with tri-n-octylammonium chloro complexes of Cu(II), Zn(II) and Co(II) of various compositions, including the N-deuterated compounds, were prepared and investigated by IR spectroscopy and conductivity measurements. Besides the well-known 2:1-complexes (TOAH⁺)₂MCl₄^2?, for which new assignments of νNH frequencies are given, complexes with a stoichiometric ratio TOA:M > 2 were found. Their cations contain the groups (TOAH …Cl…HTOA)⁺ and TOAH⁺ and they are supposed to be 3:1-complexes (TOAH…Cl…HTOA)⁺TOAH⁺MCl₄^2?. The IR spectrum of the 1:1-complex TOAH⁺CuCl_3? is given. The occurrence of the analogous 1:1-complex TOAH⁺ZnCl_3? could not be detected under the preparative conditions used.