Normal coordinate analysis of M-Si2H5-moieties in transition metal complexes and comparison to Br-Si2H5

In order to examine the influence of the transition metal on the metal-disilanyl-fragment and especially the M-Si and Si-Si-bond polarized Raman spectra of the complexes (C(5)R(5))(CO)(2)Fe-Si(2)H(5) {R=H ( 1a); R=Me ( 1b)} and (C(5)R(5))(CO)(2)(PMe(3))M-Si(2)H(5) {R=Me, M=Mo ( 2); R=H, M=W ( 3)} have been recorded. The spectral data have been evaluated and interpreted on the basis of a normal coordinate analysis of the M-SiH(2)-Si-fragment including Br-Si(2)H(5) ( 4) and comparison with examinations of the M-SiH(3)-fragment.     

Normal coordinate analysis of MSiH3 moieties in transition metal complexes and comparison to results obtained for silyl halides

In order to examine the influence of the transition metal on the metal-silyl fragment MSiH₃ and the metal-silicon bond, polarized Raman spectra of the complexes (C₅R₅)(CO)₂FeSiH₃ R = H (Cp) (1a), Me (Cp^*) (1b)], (C₅H₅)(CO)(PPh₃)FeSiH₃ (1c), (C₅Me₅)(CO)₂RuSiH₃ (2), (C₅R₅)(CO)₂(PMc₃)MoSiH₃ [R = H (3a), Me (3b)], and (C₅R₅)(CO)₂(PMe₃)WSiH₃ [R = H(4a), Me (4b)] have been recorded. The spectral data have been evaluated and interpreted on the basis of a normal coordinate analysis of the MSiH₃ core and the derived force constants and potential energy distributions were compared to results obtained for analogous halogen derivatives in the series XSiH₃ [X = Br (5), I (6)].     

Vibrational study of hydrogen bonding and structural disorder in Na2H(SO4)2, K3H(SO4)2 and (NH4)3H(SO4)2 crystals

Infrared and Raman spectra on Na₃H(SO₄)₂, K₃ H(SO₄)₂ and (NH₄)₃ H(SO₄)₂ crystals have been investigated at 300 and 100 K in the 4000 to 30 cm⁻¹ region. An assignment of bands in terms of OH group frequencies and more or less distorted tetrahedra of ammonium and sulphate ions is given. The crystallographic and spectroscopic symmetry and/or dissymetry of OHO hydrogen bonds linking sulphate ions into dimers is discussed using OH group frequencies and the splitting of the v₁ (SO₄) Raman bands as criteria. In the particular case of (NH₄)₃H(SO₄)₁ compound containing several solid phases it can be shown that the room temperature phase (II) is strongly disordered, principally because of an orientational disorder of ammonium ions, and that a progressive ordering takes place with temperature lowering.     

Synthesis, characterization, and X-ray crystal structure of the octabromodiosmate(III) salt [(C5Me4H)2OsBr]2[Os2Br8] and its conversion to [(C5Me4H)2OsBr][Os2HBr4(cod)2]

Treatment of hexabromoosmic acid, H₂OsBr₆, with 4 equiv. of tetramethylcyclopentadiene (C₅Me₄H₂) in tert-butanol at reflux for 8 h affords the unusual salt [(C₅Me₄H)₂OsBr]₂[Os₂Br₈], 1, which is the bis(tetramethylcyclopentadienyl)bromoosmocinium(IV) salt of the octabromodiosmate(III) dianion. The brown color of the salt suggests that the anion adopts an eclipsed conformation (D_4h symmetry) and this conclusion has been confirmed by a single-crystal X-ray diffraction experiment. The X-ray crystal structure indicates that the osmium atoms in the anion are disordered over two sites. The bromine atoms show no evidence of disorder and are disposed in a quasi-cubic arrangement; the two Os-Os vectors are almost exactly orthogonal to each other and each vector points toward a different pair of opposite square faces of the Br₈ cube. The Os-Os bond distances are 2.219(5) and 2.229(1) Å; the average Os-Br distance in the anion is 2.417(2) Å. Treatment of [(C₅Me₄H)₂OsBr]₂[Os₂Br₈] with excess 1,5-cyclooctadiene in ethanol at gentle reflux for 3 h affords [(C₅Me₄H)₂OsBr][Os₂HBr₄(cod)₂], 2. An X-ray crystallographic study was carried out on a sample in which the cation was a mixture of [(C₅Me₄H)₂OsBr⁺] and [(C₅Me₄H)₂OsH⁺]. The results demonstrate that the anion adopts a confacial bioctahedral structure in which the hydride ligand and two bromides bridge between the two osmium centers. The CC bonds of the cod ligands are trans to the bridging bromide groups. The Os-Os bond distance in the anion is 2.874(1) Å. The average Os-Br distance is 2.596(2) Å for the bridging bromides and 2.565(2) Å for the terminal bromides. Compound 2 is the first example of an anionic diosmium complex containing a bridging hydride. The reaction of 1 with cod also results in the formation of bis(tetramethylcyclopentadienyl)osmocene, (C₅Me₄H)₂Os, 3, which has been isolated and characterized. Treatment of (C₅Me₄H)₂Os with 1.0 equiv. of HBF₄ · Et₂O affords the osmocinium salt [(C₅Me₄H)₂OsH][BF₄].     

Normal coordinate analysis of CF3CH3

Normal coordinate calculations were made for CF₃CH₃, using a twenty-two parameter modified valence force field. Thirteen force constants were constrained to the CF₃CH₂X values and nine were adjusted to fit the twelve frequencies, resulting in an average error of 2.3 cm^/t-1. The CF₃ group force constants should be useful in calculations for other compounds containing this group.     

Synthesis and crystal structures of organometallic compounds containing the ligands C(SiMe3)2(SiMe2H) and C(SiMe2Ph)2(SiMe2H)

Metallation of (HMe₂Si)(Me₃Si)₂CH (1) by LiMe gave the organolithium compound Li(THF)₂C(SiMe₃)₂(SiMe₂H) (2a), which exists in toluene solution as a mixture of covalent species and ion pairs [Li(THF)₄][Li{C(SiMe₃)₂(SiMe₂H)}₂] (2b). Treatment of a mixture of 1 and LiMe with KOBu^t gave KC(SiMe₃)₂(SiMe₂H) (3). This reacted with AlMe₂Cl in hexane/THF to give Al(THF)Me₂{C(SiMe₃)₂(Si Me₂H)} (4). Treatment of (HMe₂Si)(PhMe₂Si)₂CH (5) with LiMe in Et₂O/THF gave the THF adduct [Li(THF)₂C(SiMe₂Ph)₂(SiMe₂H)] (6); in the presence of KOBu^t the solvent-free [K][C(SiMe₂Ph)₂(SiMe₂H)] (7) was obtained. Crystal structure determinations showed that 6 crystallizes in a molecular lattice and 7 in an ionic lattice in which the coordination sphere of the potassium comprises phenyl groups and hydrogen atoms attached to silicon, as well as the central carbon of the bulky carbanion. Compound 7 reacted with an excess of AlMe₂Cl to give [AlClMe{C(SiMe₂Ph)₂(SiMe₂H)}]₂ (8) and AlMe₃. A small amount of the methoxo derivative [Al(OMe)Me{C(SiMe₂Ph)₂(SiMe₂H)}]₂ (9) was obtained as a byproduct, presumably after the accidental admission of traces of air. X-ray structural determinations showed that 8 forms halogen-bridged dimers, with the bulky ligands in the anti-configuration, and 9 forms methoxo-bridged species in which the bulky ligands are syn.     

Rearrangement of phosphinohydrazide ligand -NPh-N(PPh2)2 in transition metal coordination sphere: Synthesis and characterization of nickel and cobalt spirocyclic complexes M(NPh-PPh2N-PPh2)2 and their properties

The reaction of diphosphinohydrazine PhNH-N(PPh₂)₂ (1) with cobalt(II) silylamide, Co[N(SiMe₃)₂]₂, proceeds via formation of unstable phosphinohydrazide complex Co[NPh-N(PPh₂)₂]₂ followed by rearrangement to a new chelating compound Co(NPh-PPh₂N-PPh₂)₂ (2). Disproportionation of nickel(I) silylamide, (Ph₃P)₂Ni-N(SiMe₃)₂, in the presence of 1, yields Ni(0) and Ni(II) phosphinoamide complexes: Ni[(Ph₂P)₂N-NPhH]₂ (3), Ni(NPh-PPh₂N-PPh₂)₂ (4). X-ray analysis reveals tetrahedral environment of the cobalt atom in 2 and square-planar environment of the nickel atom in cis-4. In contrast to the crystalline patterns, the solutions of 2 in THF or toluene have EPR signal which is typical to square-planar low-spin d⁷ cobalt complex. The reactions of 2 with dioxygen, elemental sulfur and diphenyldiazomethane led to the spirocyclic insertion products Co(NPh-PPh₂N-PPh₂X)₂ (X = O, S, NNCPh₂) while the absorption of carbon monoxide is reversible.     

Synthesis and structures of new metallocene derivatives of lanthanides. Molecular structures of the complexes (C13H9)2Eu(THF)2 and (C5Me4H)2YbI(THF)

The divalent europium bis-fluorenyl complex (C₁₃H₉)₂Eu(THF)₂ was synthesized by the metathesis reaction of EuI₂(THF)₂ with two equivalents of fluorenylpotassium and by the protolytic substitution of the naphthalene ligand in the (C₁₀H₈)Eu(THF)₂ complex using the reaction with fluorene. According to X-ray diffraction data, the complex displays a skewed sandwich structure, in which one fluorenyl ligand is η⁵-coordinated to the metal atom, whereas the η³-coordination mode makes a great contribution to the coordination of another ligand. The (C₅Me₄H)₂YbI(THF) complex was synthesized by the reaction of YbI₃(THF)₂ with two equivalents of (C₅Me₄H)K. The structure of the complex was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 530–534, March, 2008.     

Proton dynamics in superionic phase of Tl3H(SO4)2

Electrical properties and ¹H-NMR absorption line have been measured, in order to investigate proton dynamics in a superionic phase in Tl₃H(SO₄)₂. From the measurement of the thermoelectric power, it is found that a majority carrier in electrical conductivity is a proton. Moreover, from ¹H-NMR measurement it is also found that the activation energy 0.33 eV of the hopping motion of protons is close to 0.38 eV as observed in the electrical conductivity measurement. These results indicate that the electrical conductivity in the superionic phase is caused by the hopping motion of protons accompanied by the breaking of the hydrogen bonds.     

Dimerization of methyl acrylate by homogeneous transition metal catalysis. Part II. Activation of dihydridoruthenium(II) phosphane complexes by CF3 3H

The tail-to-tail dimerization of methyl acrylate (MA) in the presence of H₂Ru(PPh₃)₄ (1) or H₂(CO)Ru(PPh₃) ₃ (2) and CF₃SO₃H to give a mixture of linear dimers is described. In neat methyl acrylate at 85°C the reaction shows turnover numbers of 300 in 20 h and 640 in 7 d. Mechanistic studies show that the initial step of the reaction is the reduction of H₂Ru(PPh₃)₄ (1) by MA to form Ru(MA)₂ (PPh₃)₂ (5). After activation with CF₃SO₃H the catalytically active species contains only one phosphane ligand. The basic mechanistic features of the dimerization reaction have been revealed by ²H NMR spectroscopy involving the use of CF₃SO₃D. The deuterium-labelling studies indicate the intermediate formation of a ruthenium(II) hydride complex. Subsequent olefin insertions in this complex, followed by β-hydride elimination,lead to the linear dimeric products.     

Synthesis and reactions of the transition metal substituted tin hydride HSn[Mo(CO)3C5H5]3

Reaction of HMo(CO)₃C₅H₅ and Sn(C₅H₅)₂ produces the tin hydride HSn[Mo(CO)₃C₅H₅]₃ (I). Reaction of I with CCl₄, CHCl₃, or CH₂Cl₂ gives ClSn[Mo(CO)₃C₅H₅]₃ (II). With hydrogen chloride the hydride I reacts to produce the dichloride Cl₂Sn[Mo(CO)₃C₅H₅]₂. The first step in this reaction is cleavage of the SnH bond to produce the chloride II. The hydride I reacts with acetic acid to produce the diacetate (CH₃COO)₂Sn[Mo(CO)₃C₅H₅]₂.     

Thermal analysis of β-Co2(OH)3Cl and Zn5(OH)5Cl2 · H2O

Samples of β-Co₂(OH)₃Cl and Zn₅(OH)₈Cl₂ · H₂O have been prepared and their thermal decomposition studied in air and N₂ by DTA and TG up to 1000°C. X-Ray diffraction analysis of the thermal treatment products in air at various temperatures from 100 to 100°C was also carried out. The results obtained made it possible to establish the steps through which the pyrolysis of both compounds proceeds.     

Structural research on non transition metal double nitrites: Crystal structure, optical absorption and emission of TlBa2(NO2)5

The thallium-barium double nitrite, TlBa₂(NO₂)5, is pyroelectric in the 77-600 K range and crystallizes in thePca2 ₁ space group. The lattice constants at 293 K are: a = 17.868(12),b = 4.934(3),c = 13-426(11) A (MoKa, λ = 0.71069 A). There are four stoichiometric units in the unit cell of volume V= 1184(1) A³ (D _o = 3.98,D _x = 3.979 Mgm⁻³),F (000) = 1232, μ = 20.36mm⁻¹. The crystal structure was solved by Patterson and Fourier methods and refined by least-squares to a final conventional agreement indexR = 0.053 for 1371 independent reflections collected in a θ range of 3–30°, using MoKα radiation. There are two independent barium atoms surrounded by NO ₂ ⁻ groups, both with coordination number 10 and distances in the ranges Ba-O = 2.69(4)-3.18(4) A and Ba-N = 3.01(4)-3.18(4) A. The environment of thallium is clearly affected by the lone-pair stereoactivity and involves 12 Tl-O and Tl-N contacts less than 3.5A, but only four Tl-O distances are shorter than 3 A (min. 2.76(2), max. 2.85(3) A), with a pyramidal coordination and thallium at the apex of the pyramid. All these coordination polyhedra are joined in chains running along the shortest lattice vector [010]. The single crystal electronic spectra, studied in absorption with polarized light and in photostimulated emission, are interpreted as due to transitions involving NO ₂ ⁻ electronic levels perturbed by Tl⁺, whose spin-orbit interaction makes probable also the forbidden singlet-triplet transitions, in agreement with the interpretative picture given for post-transition metal nitrites.     

A straightforward synthesis of cationic nitrile ligated transition metal complexes with the [B(C6F5)4] anion

Nitrile ligated transition metal complexes bearing polyfluorinated tetra(aryl)borates as counter anions are highly active initiators/mediators for various polymerization reactions. However, the methods for their preparation are still far too inefficient for widespread use in applied research or in industry. Accordingly, an improved synthesis for two of the most promising species in this assemblage of complexes, namely [Cu(C₆H₅CN)₅][B(C₆F₅)₄]₂ and [Zn(CH₃CN)_4/6][B(C₆F₅)₄]₂, has been developed. This route provides easy access to pure products on a gram scale, by the reaction of copper(II)acetate and diethyl zinc with [H(OEt₂)₂][B(C₆F₅)₄]. Additionally, a new route for the synthesis of the oxonium acid as precursor has been developed, allowing a fast preparation of this compound. Elementary analysis and X-ray crystal structures are in accordance with earlier results on the ease of solvent loss and theoretical studies dealing with acetonitrile-exchange reactions.     

Co3{CH3C(NH3)(PO3H)(PO3)}2 {CH3C(NH3)(PO3H)2}2(H2O)4·2H2O: A cobalt 1-aminoethylidenediphosphonate with a layer structure

This paper describes the structure and magnetic properties of a novel cobalt 1-aminoethylidenediphosphonate compound, namely Co₃{CH₃C(NH₃)(PO₃H)(PO₃)}₂{CH₃C(NH₃)(PO₃H)₂}₂(H₂O)₄·2H₂O (1). The structure contains a trimer unit of Co₃{CH₃C(NH₃)(PO₃H)(PO₃)}₂ in which two equivalent phosphonate ligands chelate and bridge the three cobalt ions. Each trimer unit is further linked to its four equivalent neighbors through corner-sharing of CoO₆ octahedra and CPO₃ tetrahedra, forming a two-dimensional layer in the bc-plane which contains 12-membered rings. These layers are connected to each other by extensive hydrogen bonds. Magnetic studies show that weak antiferromagnetic interactions are mediated between the cobalt ions. Crystal data for 1: monoclinic, space group C2/c, a=27.727(4), b=7.1091(11), , β=118.488(3), , Z=2.     

Synthesis and Anti-inflammatory Action of （η-C5H5 ）2Ti（ Sal）2 and （η-C5H5 ）2Ti（Clo）2

IntroductionSince K pf[1]discovered that dicyclopenta die-nyltitanium dichloride possesses antitumour action in1979,a large number of cyclopentadienyltitanium com-plexes with different substituents have been synthe-sized[2,3].The experimental data reveal …     

Investigation of interaction of olefin-bonded transition metal complexes by gas chromatography. Diphenylphosphine complexes with CoCl2 and CoBr2

Summary Packings consisting of diphenylphosphine complexes with CoCl₂ and CoBr₂, chemically bonded to the silica surface, were synthesized and their retention parameters determined. The packings are capable of specifically interacting with electron-donating compounds by forming -complexes. The interaction is considerably stronger in the case of CoBr₂-containing packing than in the case of CoCl₂-containing packing.