Alternativ-Liganden. XXX [1] Neue Tripod-Liganden XM' (OCH2PMe2)n(CH2CH2PMe2)3−n (M' = Si; Ge; n = 0–3) für Käfigstrukturen

Alternative Ligands. XXX Novel Tripod Ligands XM' (OCH₂PMe₂)_n(CH₂CH₂PMe₂)_3?n (M' = Si, Ge; n = 0–3) for Cage Structures Attempts to prepare new tripod ligands XSi(OCH₂PMe₂)₃ [X = CF₃ ( 15 ), C₆F₅ ( 16 ), NMe₂ ( 17 ), Cl ( 18 ), F ( 19 ), H ( 20 ), OEt ( 21 ), OMe ( 22 )] prove to be unsuccessful in spite of using different pathways, because the groups X undergo following reactions giving insoluble solids (polyadducts) or form inseparable mixtures, e. g. (RO)_nSi(OCH₂PMe₂)_4?n (R = Me, Et). In many cases Si(OCH₂PMe₂)₄ ( 13 ) can be isolated from the reaction mixture. The syntheses of the ligands XSi(CH₂CH₂PMe₂)₃ [X = NMe₂ ( 6 ), Cl ( 7 ), F ( 8 ), OMe ( 9 ), Vi ( 12 )], Si(OCH₂PMe₂)₄ ( 13 ) und Me₃GeOCH₂PMe₂ ( 14 ) are successful. The compounds MeSi(OCH₂PMe₂)₂CH₂CH₂NMe₂ ( 10 ) and MeSi(OCH₂PMe₂)₂CH₂CH₂P(CF₃)₂ ( 11 ) with different donor groups are obtained in good yields. The preparative program includes the synthesis of the known representatives MeSi(OCH₂PMe₃)₃ ( 1 ), MeSi(OCH₂PMe₂)₂CH₂CH₂PMe₂ ( 2 ), MeSi(OCH₂PMe₂)(CH₂CH₂PMe₂)₂ ( 3 ), MeSi(CH₂CH₂PMe₂)₃ ( 4 ) and MeGe(OCH₂PMe₂)₃ ( 5 ). Important preparative steps are the substitution of M'Cl (M' = Si, Ge) by Me₂PCH₂O groups and the photochemically induced or base catalyzed addition of HNMe₂, HPMe₂ or HP(CF₃)₂ to SiVi functions. The novel compounds are characterized by analytical and spectroscopic (IR, NMR, MS) investigations.     

Metallorganische Lewis-Säuren. XLII. Carbonyl- und Nitrosyl-Komplexe von Mangan und Rhenium mit schwach koordinierten Anionen (Ph3P)2(ON)2MnX, (Ph3P)n(OC)5–nMX (M = Mn,Re; n = 1, 2; X = FBF3, OSO2CF3, OSO2F,OCORf)

Organometallic Lewis Acids. XLII. Carbonyl- and Nitrosyl Complexes of Manganese and Rhenium of Weakly Coordinated Anions (Ph₃P)₂(ON)₂MnX, (Ph₃P)_n(OC)_5–nMX (M = Mn, Re; n = 1, 2; X = FBF₃, OSO₂CF₃, OSO₂F, OCOR_f) The complexes (Ph₃P)₂(ON)₂MnX (X = FBF₃, OSO₂CF₃, OSO₂F, OCOCF₃, OCOC₃F₇) and (Ph₃P)_n(OC)_5–nMX (M = Mn, Re; n = 1, 2; X = FBF₃, OSO₂CF₃) have been obtained by reaction of (Ph₃P)₂(ON)₂MnH and (Ph₃P)_n(OC)_5–nMeMe with the corresponding acids HX or from (Ph₃P)_n(OC)_5–nReBr (n = 1, 2) with silver salts AgX, respectively. The compounds have been characterized by their IR and partially by ¹⁹F-NMR data. An efficient method for the preparation of the hydride (Ph₃P)₂(ON)₂MnH is reported.     

Molecular and electronic structure of several heterofullerene BNC58 and B2N2C56 oligomers and [B2N2C56] n macromolecule

Molecular and electronic structure of heterofullerene BNC₅₈ (C _s) and B₂N₂C₅₆ (C _2h) monomers, B₂N₂C₁₁₆ and B₄N₄C₁₁₂ dimers, and B₆N₆C₁₆₈ trimer (the last three molecules withC _2h symmetry) was simulated by the MNDO method. Clusters BNC₅₈ and B₂N₂C₅₆ are formed by replacement of carbon atoms participating in one or two of the most distant oppositely lying (6,6)-type C−C bonds in fullerene C₆₀ by B and N atoms. In one of the two studied isomers of the B₂N₂C₁₁₆ dimer, the monomers are linked by the four-membered carbon cycle, while the heteroatoms form the most distant oppositely lying bonds of the dimer. In the other isomer of the B₂N₂C₁₁₆ dimer, as well as in the B₄N₄C₁₁₂ dimer and B₆N₆C₁₆₈ trimer, the monomers are linked by four-membered B₂N₂ cycles with alternation of the atoms. For all the systems studied, the optimum geometric parameters, heats of formation, ionization potentials, and atomic charges were calculated. Dimerization energies of heterofullerenes BNC₅₈ and B₂N₂C₅₆ lie in the range from 33 to 49 kcal mol⁻¹. It was found that the B₂N₂C₁₁₆ dimer, in which the monomers are linked by the four-mernbered carbon cycle, is the most stable system. In the case of B₂N₂C₅₆ trimerization, the energy gain (compared to the triple monomer energy) is about twice as large as the dimerization energy. Molecular structure of the quasi-linear [B₂N₂C₅₆) _n macromolecule was simulated, and extended Hückel calculations of its energy band structure by the crystal orbital method were performed. It was found that the electron energy spectrum is of semiconducting type (the band gap is equal to 1.27 eV. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 431–435, March, 1999.     

Crystallographic and Theoretical Investigations of Er2@C2 n (2 n=82, 84, 86): Indication of Distance-Dependent Metal–Metal Bonding Nature

Successful isolation and characterization of a series of Er-based dimetallofullerenes present valuable insights into the realm of metal–metal bonding. These species are crystallographically identified as Er₂@C_s(6)-C₈₂, Er₂@C_3v(8)-C₈₂, Er₂@C₁(12)-C₈₄, and Er₂@C_2v(9)-C₈₆, in which the structure of the C₁(12)-C₈₄ cage is unambiguously characterized for the first time by single-crystal X-ray diffraction. Interestingly, natural bond orbital analysis demonstrates that the two Er atoms in Er₂@C_s(6)-C₈₂, Er₂@C_3v(8)-C₈₂, and Er₂@C_2v(9)-C₈₆ form a two-electron-two-center Er−Er bond. However, for Er₂@C₁(12)-C₈₄, with the longest Er⋅⋅⋅Er distance, a one-electron-two-center Er−Er bond may exist. Thus, the difference in the Er⋅⋅⋅Er separation indicates distinct metal bonding natures, suggesting a distance-dependent bonding behavior for the internal dimetallic cluster. Additionally, electrochemical studies suggest that Er₂@C_82–86 are good electron donors instead of electron acceptors. Hence, this finding initiates a connection between metal–metal bonding chemistry and fullerene chemistry.     

Molybdenum-95 nuclear magnetic resonance of a series of phosphine and phosphite substituted molybdenum carbonyls Mo(CO)6−n (L) n (n=1, 2, 3, 4, 5)

Molybdenum-95 NMR spectra of a series of phosphine and phosphite substituted molybdenum carbonyls Mo(CO)_6-n L _n [L=P(OCH₃)₃ n=1, 2, 3, 4, 5,L=P(OC₂H₅)₃ n=1, 2, 3,L=P(C₆H₅)₃ n=1] including isomers (cis,trans,fac,mer) are reported, A large range of chemical shifts is found for the title compounds. The coupling constants¹ J(⁹⁵Mo-³¹P) are derived either from⁹⁵Mo-NMR spectra or³¹P-NMR spectra. Syntheses of the measured compounds were performed by thermal or photochemical ligand substitution.

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Molybdän-95 NMR einer Reihe von Phosphin- und Phosphit-substituierten Molybdäncarbonylen Mo(CO)_6–n(L) _n (n=1, 2, 3, 4, 5)

Zusammenfassung Es werden die⁹⁵Mo-NMR-Spektren der im Titel genannten Verbindungen mitL=P(OCH₃)₃ n=1–5,L=P(OC₂H₅)₃ n=1–3 undL=P(C₆H₅)₃ n=1, einschließlich von Isomeren (cis, trans, fac, mer) angegeben. Für die chemischen Verschiebungen wurde ein sehr weiter Bereich beobachtet. Die Kopplungskonstanten¹ J(⁹⁵Mo-³¹P) wurden entweder von den⁹⁵Mo- oder³¹P-NMR-Spektren ermittelt. Die Synthese der Verbindungen erfolgte mittels thermischem oder photochemischem Ligandenaustausch.

     

Systematic study of (Na n )2 dimer transient state in Na n +Na n collisions (n=8, 9, 19, and 20)

From distance dependent tight-binding molecular dynamics simulations, we systematically study the Na _n +Na _n collision dynamics around the first two closed shells (n=8 and 20). We investigate the stability of sodium cluster dimers (Na _n )₂, for many events with random relative orientation at finite temperature, various impact parameters and incident energies. We find that (Na₈)₂, (Na₉)₂, (Na₁₉)₂ and (Na₂₀)₂ can exist during about 3000 fs in central collisions while they can exist up to about ten thousands fs in peripheral collisions with larger impact parameters in fusion mechanism at c.o.m energy per atomE _cm/n=0.025 eV. We observe that the lower the incident energy, the longer the lifetime of the cluster dimers in both central and peripheral collisions. There is no apparent difference in the dynamical stability of (Na₈)₂ and (Na₉)₂, (Na₁₉)₂ and (Na₂₀)₂ although (Na₈)₂ and (Na₂₀)₂ are respectively slightly colder than (Na₉)₂ and (Na₁₉)₂ for the same incident energy per atom and the same impact parameter.     

A Theoretical Study of LiHe+ n , NaHe+ n , and MgHe+ n Complexes, with n=1, 2, 3, 4

The LiHe⁺ _n , the NaHe⁺ _n , and the MgHe⁺ _n complexes with n=1, 2, 3, 4 were studied using ab initio calculations with the MP2/6-311+G(3df, 3pd) method. The complexes are found to be stable. For the n=1 complexes, previous results were available and the calculations performed are in good agreement with those results. This lends credibility to the results obtained for the complexes with higher n.     

Die Reaktion von Cyanid-Ionen mit Trimethylgallium. Die Kristallstrukturen von [Cs{CN(GaMe3)2}]n und [Cs(Toluol)2{CN(GaMe3)2}]n

The Reaction of Cyanide Ions with Trimethylgallium. The Crystal Structures of [Cs{CN(GaMe₃)₂}]_n (1) and [Cs(toluene)₂{CN(GaMe₃)₂}]_n (2) CsCN reacts with GaMe₃ in the molar ratio of 1 : 2 in the absence of additional solvent to the metalate [Cs{CN(GaMe₃)₂}] ( 1 ). 1 can be recrystallized from MeCN/toluene, forming [Cs(toluene)₂{CN(GaMe₃)₂}] ( 2 ). If CsCN is treated with one equivalent GaMe₃ in Et₂O at 20 °C, the metalate [Cs(NCGaMe₃)] can be isolated. 1 – 3 were characterized by NMR, IR, and MS techniques. In addition, X-ray structure analyses of 1 and 2 were prepared. According to the structural characterization 1 consists of a helix of Cs⁺ ions and side-on coordinated anions [Me₃GaCNGaMe₃]^–, running along [010]. π-Electron-Cs⁺ contacts between Cs cations and toluene molecules are dominating the structure of 2 . The residual equatorial positions at the [Cs(toluene)₂]⁺ sandwich-ion are occupied by Cs⁺-hydrogen(methyl) interactions. A three-dimensional network is the result of the contacts between cations and anions.     

Ab initio study of cyclic siloxanes (H2SiO)n: n = 3, 4, 5

The geometry optimizations for several conformations of tri-, tetra-, and pentacyclosiloxane (H₂SiO)_n (n = 3, 4, and 5) were carried out, and the relative stabilities were compared at the Hartree-Fock (HF) and second order perturbation theory (MP2) levels of theory using the 6–31G* and 6–311G(d, p) basis sets. At the highest levels of theory, the only minimum for n = 4 (D₄) occurs at the highly symmetric D_4h structure. In contrast, several, nearly isoenergetic, minima are found on the D₅ surface. These have C₁, C₂, C_s, and D_5h symmetries. While the C₁ structure has the lowest MP2/6–311G(d, p) energy, this species is predicted to be highly fluxional, and the distribution of isomers is dependent on temperature. © 1996 by John Wiley & Sons, Inc.     

ChemInform Abstract: Pseudopotential Investigations on the Molecules Cu2Si2, Cu2Sn2, Cu4Si4, and Cu4Sn4

show the equilibrium structures to be the butterfly arrangement for the Cu₂X₂ clusters and the heterocubane arrangement for the Cu₄X₄ clusters.     

Formation and structure of diruthenium complexes Ru2(CO)6−n (PPh3) n {μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} (n=1, 2)

Ruthenium carbonyl triphenylphosphine complexes Ru₂(CO)_6−n (PPh₃) _n {μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} (n=1, 2) were obtained by the reaction of complex Ru₂(CO)₆{μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} containing the ruthenacyclopentadiene moiety with PPh₃ in refluxing toluene. The complexes were characterized by IR and by¹H,¹³C, and³¹P NMR spectroscopy, and by X-ray analysis. The monophosphine derivative is identical to the complex formed by fragmentation of the Ru₃(CO)₈(PPh₃){μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} cluster and contains the PPh₃ ligand at the ruthenium atom of the ruthenacyclopentadiene moiety. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1836–1843, September, 1998     

Extraction Von Molybdän(V) MIT O,O, S-Tripropyldithiophosphat Aus Salzsauren Lösungen

Abstract

The solvent extraction of molybdenum with o,o,s-tripropyldithiophosphate from hydrochloric acid has been studied. The extractable species is H₂[MoOCl₅] .2 (C₃H₇O)₂-P(S)SC₃H₇ and the thiophosphate can be used to separate molybdenum from Th, Zr, Ti⁴⁺, V⁵⁺, Nb, Ta, Cu²⁺, Fe²⁺, Co²⁺, Ni and Mn²⁺.     

Kinetics of thermal dehydration of Ce2(SO4)2, n(H,D)2O (n=5, 8, 9)

The thermal dehydration of Ce₂(SO₄)₃·5H₂O, Ce₂(SO₄)₃·8H₂O, Ce₂(SO₄)₃·9H₂O and their isomorphous deuterated compounds was studied by means of thermogravimetric measurements. A kinetic analysis of the TG curves obtained was carried out by computer. The thermal stability, Arrhenius parameters and mechanism of dehydration were investigated.     

Modified Tellurium Subhalides in the New Structure Type [Te15X4]n[MOX4]2n (M = Mo,W; X = Cl,Br)

The reactions of Te₂Br with MoOBr₃, TeCl₄ with MoNCl₂/MoOCl₃, and Te with WBr₅/WOBr₃ yield black, needle-like crystals of [Te₁₅X₄][MOX₄]₂ (M = Mo, W; X = Cl, Br). The crystal structure determinations [Te₁₅Br₄][MoOBr₄]₂: monoclinic, Z = 1, C2/m, a = 1595.9(4) pm, b = 403.6(1) pm, c = 1600.4(4) pm, β = 112.02(2)°; [Te₁₅Cl₄][MoOCl₄]₂: C2/m, a = 1535.3(5) pm, b = 402.8(2) pm, c = 1569.6(5) pm, β = 112.02(2)°; [Te₁₅Br₄][WOBr₄]₂: C2, a = 1592.4(4) pm, b = 397.5(1) pm, c = 1593.4(5) pm, β = 111.76(2)° show that all three compounds are isotypic and consist of one-dimensional ([Te₁₅X₄]²⁺)_n and ([MOX₄]^?)_n strands. The structures of the cationic strands are closely related to the tellurium subhalides Te₂X (X = Br, I). One of the two rows of halogen atoms that bridges the band of condensed Te₆ rings is stripped off, and additionally one Te position has only 75% occupancy which leads to the formula ([Te₁₅X₄]²⁺)_n (X = Cl, Br) for the cation. The anionic substructures consist of tetrahalogenooxometalate ions [MOX₄]^? that are linked by linear oxygen bridges to polymeric strands. The compounds are paramagnetic with one unpaired electron per metal atom indicating oxidation state M^v, and are weak semiconductors.     

ChemInform Abstract: The New Misfit Compound (BiSe)1.15(TiSe2)2 and the Role of Dimensionality in the Cux(BiSe)1+δ(TiSe2)n Series.

Single crystals of (BiSe)_1.15(TiSe₂)₂ and (BiSe)_1.13(TiSe₂) are prepared from Bi, Ti, and Se in the molar ratio1:1:3 by vapor transport with TeCl₄ as transport agent (750—680 °C, 7 d).     

Fluorosubstituted rhodacarboranes 3,4-(R3P)2-3-H-3,1,2-RhC2B9H11−n F n (n=1, 2, 4): Synthesis, molecular structure, and catalytic properties in hydrosilylation of styrene and phenylacetylene

Hydridorhodacarboranes 3,3-(Ph₂RP)₂-3-H-3,1,2-RhC₂B₉H_11−n F _n (R=Ph, Me;n=1, 2, 4) containing F atoms at the B atoms of the π-carborane ligand were synthesized from (Ph₃P)₃RhCl or (Ph₂MeP)₃RhCl andnido-7,8-C₂B₉H_12−n F _n ⁻ (n=1, 2, 4) salts. Hydridorhodacarboranes 3,3-(Ph₂MeP)₂-3-H-3,1,2-RhC₂B₉H_11−n F _n readily exchange the H atom at the Rh atom for the Cl atom under the action of CH₂Cl₂ to give 3,3-(Ph₂MeP)₂-3-Cl-3,1,2-RhC₂B₉H_11−n F _n . The structures of the 3,3-(Ph₃P)₂-3-H-3,1,2-RhC₂B₉H₇F₄ and 3,3-(Ph₂MeP)₂-3-Cl-3,1,2-RhC₂B₉H₉F₂ complexes were determined by X-ray diffraction analysis. Catalytic properties of the rhodacarbonanes obtained in hydrosilylation of styrene and phenylacetylene by PhMe₂SiH were studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 570–578, March, 1997.     

Multiplicative degree-Kirchhoff index and number of spanning trees of a zigzag polyhex nanotube TUHC[2n, 2]

Let L_n denote the linear hexagonal chain containing n hexagons. Then identifying the opposite lateral edges of L_n in ordered way yields TUHC[2n, 2] , the zigzag polyhex nanotube, whereas identifying those of L_n in reversed way yields M_n, the hexagonal Möbius chain. In this article, we first obtain the explicit formulae of the multiplicative degree-Kirchhoff index, the Kemeny's invariant, the total number of spanning trees of TUHC[2n, 2] , respectively. Then we show that the multiplicative degree-Kirchhoff index of TUHC[2n, 2] is approximately one-third of its Gutman index. Based on these obtained results we can at last get the corresponding results for M_n.     

New chain polymer [Yb(tpa)(H2O)2Co(CN)6]n · 7n H2O: synthesis,structure, and magnetic characteristics

The 3d– 4f heterometallic polymeric complex, namely [Yb(tpa)(H₂O)₂Co(CN)₆]_n·7n H₂O [tpa = tris(2-pyridylmethyl)- amine], was synthesized and characterized. Its polymer structure is formed of [Yb(tpa)(H₂O)₂Co(CN)₆] chains and crystallization water molecules with a two-capped trigonal prism Yb³⁺ coordination polyhedron; the Yb³⁺ coordination number is 8, and the coordination site is YbN₆O₂. Magnetic characteristics indicate that the complex exhibits the properties of a single-chain magnet with a magnetization reversal barrier(!E/k_B) of 42 K.     

Photochemical reactions of Re(CO)5Br with Ph2P(CH2) n PPh2 (n = 1, dppm; 2, dppe; 3, dppp)

The new complexes fac-[Re(CO)₃Br{Ph₂P(CH₂) _n PPh₂}] (1a–3a) [(1a), n = 1; (2a), n = 2; (3a), n = 3] and [Re₂(CO)₈Br₂{-Ph₂P(CH₂) _n PPh₂}] (1b–3b) [(1b), n = 1; (2b), n = 2; (3b), n = 3] have been prepared by the photochemical reaction of Re(CO)₅Br with Ph₂P(CH₂) _n PPh₂ (n = 1, dppm; 2, dppe; 3, dppp). The complexes have been characterized by elemental analysis, mass spectroscopy, f.t.-i.r. and ³¹P-[¹H]-n.m.r. spectrometry. The spectroscopic studies suggest cis-chelate bidentate coordination of the ligand in fac-[Re(CO)₃Br{Ph₂P(CH₂) _n PPh₂}] (1a–3a) and cis-bridging bidentate coordination of the ligand between two metals in [Re₂(CO)₈Br₂{cis--Ph₂P(CH₂) _n PPh₂}] (1a–3a).     

ChemInform Abstract: Synthesis,Structural Characterization and Optical Properties of a New Cesium Aluminum Borate,Cs2Al2B2O7.

The new title compound is prepared by solid state reaction of Cs₂CO₃, Al₂O₃, and H₃BO₃ (1000 °C).