Synthesis and properties of ansa-titano- and ansa-zirconocenes

A series of methyl and allyl derivatives of ansa-titano- and ansa-zirconocenes with isopropylidene or dimethylsilyl bridging groups were synthesized. A dinuclear complex, [Me₂C(C₅H₄)₂]₂Ti₂O₂, resulting from the thermal decomposition of the corresponding dimethyl derivative of ansa-titanocene in the air, was characterized by X-ray diffraction analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 967–969, May, 1993.     

On the Reactivity of Metal and Organometallic Halides and Pseudohalides Towards Stannosiloxane (Ph3Sn-O-SiPh3)

Abstract

Interactions of HgX₂ (X = Cl, Br, I, SCN, CN, NCO), SbCl₃, TeCl₄, and PhTeCl₃ with Ph₃Sn-O-SiPh₃ at room temperature have been found to proceed with the simultaneous cleavage of Sn-O and Si-O bonds, invariably yielding Ph₂SnO, Ph₃SiX, and the corresponding organo-mercury, -antimony, and -tellurium derivatives. The course of the reactions suggests the instability of the Sn-O-M (M = Hg, Sb, Te) system.

GRAPHICAL ABSTRACT      

Phosphor-1,1-Diselenolato Metal Complexes of Group 11 and 12

Abstract

Several copper and silver clusters containing diselenophosphate ligands such as tetranuclear [Cu{Se₂P(OR)₂}]₄, hexanuclear [Ag{Se₂P(OR)₂}]₆, octanuclear [Cu₈(μ₈-Se)}Se₂P(OR)₂}₆], [Ag₈(μ₈-Se)}Se₂P(OR)₂}₆], [Cu₈(μ₈-X)}Se₂P(OR)₂}₆](PF₆), [Ag₈(μ₈-X)}Se₂P(OR)₂}₆](PF₆), decanuclear [Ag₁₀(μ₁₀-Se)}Se₂P(OR)₂}₈], undecanuclear [Cu₁₁(μ₉-Se)(μ₃-X)₃}Se₂P(OR)₂}₆], [Ag₁₁(μ₉-Se)(μ₃-X)₃}Se₂P(OR)₂}₆], and dodecanuclear [Cu₁₂(P₂Se₆)}Se₂P(OR)₂}₈] have been isolated. All these clusters were well characterized in the solid-state and solution phase by elemental analysis, positive FAB mass spectrometry, multinuclear NMR (¹H, ³¹P, and ⁷⁷Se), and single crystal X-ray diffraction. In addition, tetranuclear zinc clusters [Zn₄(μ₄-Se){Se₂P(OPr)₂}₆], and [Zn₄(μ₄-O){Se₂P(OR)₂}₆] (R = Et, ⁱPr) also are synthesized and characterized. Solution studies of both [M{Se₂P(OEt)₂}₂]∞ and [M₂{Se₂P(OⁱPr)₂}₄] (M = Zn, Cd) which display a monomer-dimer equilibrium in solution were performed by VT ³¹P NMR in CD₂Cl₂.     

Synthesis, characterisation and thermal analysis of copper (II) and chromium (II, III) hydrazine carboxylates

Copper(II) hydrazine carboxylate monohydrate, Cu(N₂H₃COO)₂·H₂O and chromium (II, III) hydrazine carboxylate hydrates, Cu(N₂H₃COO)₂·H₂O and Cu(N₂H₃COO)₂·3H₂O have been prepared and characterised by chemical analysis, IR, visible spectra and magnetic measurements. Thermal analysis of the copper complex yields a mixture of copper metal and copper oxide. Chromium complexes on thermal decomposition yield Cr₂O₃ as residue. Decomposition of chromium(HI) complex under hydrothermal conditions yield CrOOH, a precursor to CrO₂.     

Alpha and gamma spectrometry for determination of natural and artificial radionuclides in tea, herbal tea and camomile marketed in Italy

Several kinds of tea, camomile and herbal tea were analysed to determine natural and artificial radioactivity. The radionuclides were determined by alpha (²¹⁰Po) and gamma (²²⁸Ac, ²¹⁴Pb, ²¹⁴Bi, ²¹⁰Pb, ⁴⁰K and ¹³⁷Cs) spectrometry. ²²⁸Ac ranged between 0.6 and 9.0 Bq kg⁻¹_dry; ²¹⁰Po between 1.90 and 36.1 Bq kg⁻¹_dry; ²¹⁴Pb and ²¹⁴Bi between 0.7 and 4.9 Bq kg⁻¹_dry; ²¹⁰Pb between < 10.0 and 58.9 Bq kg⁻¹_dry; ⁴⁰K between 463 and 936 Bq kg⁻¹_dry; ¹³⁷Cs between < 0.3 and 2.6 Bq kg⁻¹_dry. The percentage of ²¹⁰Po extraction in infusion was also determined; the arithmetical mean value of percentage of ²¹⁰Po extraction resulted 20.7 ± 7.50.     

Dynamic mechanical and gas transport properties of blends and random copolymers of bisphenol-A polycarbonate and tetramethyl bisphenol-A polycarbonate

Dynamic mechanical and gas transport properties for homogeneous homopolymer blends and random copolymers of bisphenol-A and tetramethyl bisphenol-A polycarbonates (PC-TMPC) were determined. The gas transport measurements were performed at 35°C for the gases He, H₂, O₂, Ar, N₂, CH₄, and CO₂. The results show that the copolymers have lower permeability, apparent diffusion, and solubility coefficients than the blends. Permeability coefficients for blends follow a semilogarithmic ideal mixing rule while copolymers exhibit negative deviations from this. Specific volume measurements show that the free volume available for gas transport is slightly larger in copolymers than in blends of the same composition. These apparently contradictory results may relate to the differences in local mode chain motions observed for the copolymer and blend series. The γ relaxation processes in PC and TMPC seem to operate independently in the blends (no intermolecular coupling) while there is clear evidence for intramolecular coupling in the copolymers. © 1992 John Wiley & Sons, Inc.     

Electrochemical and spectral study of intramolecular charge transfer in dinuclear and polynuclear ladder complexes

The potentials of electrochemical oxidation and reduction of the polynuclear ladder complexes Cp(CO)LM-η ¹, η⁵-C₅H₄Mn(CO)₂L (M = Fe or W(CO); L = PPh₃ or CO), μ-(C≡ C)[C₅H₄(CO)₂Fe-η¹, η⁵-C₅H₄Mn(CO)₃]₂, and MeSi[C₅H₄(CO)₂Fe-η¹, η⁵-C₅H₄Mn(CO)₃]₃ were measured, and the mechanism of these processes is proposed. The change in the electron density at the atom of one metal (Fe or W) is transferred along the σ-and σ-bond chain in the cyclopentadienyl bridge to the atom of another metal (Mn) and, on the contrary, the perturbing effect of the substituent is somewhat weakened. Published In Russian In Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, Pp. 761–765, May, 2006.     

3-Phenoxy- and 3-phenylthio-1-propynyl substituted derivatives of silicon and germanium

Reactions of bromomagnesiopropargyl phenyl ethers and their isostmctural sulfides BrMgCCCH₂XPh (X = O, S) with MeVinSiCl₂, Me(CH₂Cl)SiCl₂, EtSiHCl₂, and Me₂SiHCl afforded the corresponding 3-phenoxy- and 3-phenylthio-1-propynyl substituted derivatives of silicon (PhXCH₂CC)₂SiRR¹ and PhXCH₂CCSiHMe₂ (X = O, S). Reactions of the above-mentioned Iotsitch reagents with GeCl₄ led to the corresponding germanium derivatives (PhXCH₂CC)₄Ge (X = O, S).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 511–513, March, 1994.     

Phase transition and mixed oxide-proton conductivity in germanium oxy-apatites

La_9.75□_0.25(Ge₆O₂₄)O_2.62 oxy-apatite shows a phase transition from triclinic to hexagonal symmetry at approximately 1020 K that has been characterised by high-temperature synchrotron X-ray and neutron powder diffraction, and ionic conductivity measurements. The crystal structure at 1073 K has been determined from joint Rietveld refinements of synchrotron X-ray and neutron powder diffraction data. The study shows that hexagonal-La_9.75□_0.25(Ge₆O₂₄)O_2.62 contains interstitial oxygen at the position previously reported for other oxy-germanates. Changes in the oxide conductivity associated with this structural transition are discussed. The thermal analyses showed a weight loss on heating close to 600 K very likely due to water release. The synchrotron thermodiffractometric study shows an anomaly in the cell parameters evolution at that temperature, which indicates that this residual water is located into the apatite channels. The electrical characterisation under different atmospheres (dry and wet synthetic air) indicates that there is a significant proton contribution to the overall conductivity below 600 K, mainly under wet atmosphere.     

Molecular DFT structure and packing effect of thiodipropionic and dithiodiglycolic acids and salts

Molecular and periodic DFT structure calculations of thiodipropionic and dithiodiglycolic acids, S_n[(CH₂)(COOR)]₂ (n = 1,2, R = H, Na), were performed. Computed structures were analyzed and compared to the experimental data (a C_s conformation is favored in solution than C₂ in solid state). Four close and low-energy optimized conformations were analyzed: C_2v, C₂, C_s and C₁. Small changes in the conformation stability (ΔG) and symmetry group were observed in polar medium. Periodic DFT-GGA approaches have been performed to determine the importance of weak interaction upon the crystal structure of the thiodipropionic acid, e.g., S–H and/or O–H hydrogen bonding. More SH and OH dispersed bands were observed in the optimized structure. Using a full analysis of the DOS of O–H or S–H bonding contributions, a notable interlayer bonding in the parent structure was revealed. Therefore, the presence of such weak interaction ONa⁺ or OH may thus change the point group symmetry of the crystal upon packing effect.     

Trichlorostannyl complexes of iridium with both P-donor and N-donor ligands: Preparation and activity as hydrogenation catalysts

Bis(trichlorostannyl) complex IrH(SnCl₃)₂(PPh₃)₂ (1) was prepared by allowing the chloro-derivative IrHCl₂(PPh₃)₃ to react with SnCl₂·2H₂O in ethanol. Instead, treatment of phosphite complexes IrHCl₂P₃ [P = P(OEt)₃ and PPh(OEt)₂] with SnCl₂·2H₂O gave stannyl derivatives IrCl₂(SnCl₃)P₃ (2). Pyrazole-trichlorostannyl complexes IrHCl(SnCl₃)(HRpz)P₂ (3, 4) (R = H, 3-Me; P = PPh₃, PⁱPr₃) were prepared by allowing chloro-derivatives IrHCl₂(HRpz)P₂ to react with SnCl₂·2H₂O. 1,2-Bipyridine-trichlorostannyl complexes IrHCl(SnCl₃)(bpy)P (5) (P = PPh₃, PⁱPr₃) were also prepared. Complexes 1-5 were characterised spectroscopically (IR, ¹H, ³¹P, ¹¹⁹Sn NMR) and a geometry in solution was also established. The trichlorostannyl iridium complexes were evaluated as catalyst precursors for the hydrogenation of 2-cyclohexen-1-one and cinnamaldehyde. The influence of the stannyl group, as well as the steric hindrance of both N-donor and P-donor ligands in the catalytic activity of the complexes is discussed.     

Diagnostics and decomposition mechanism in radio-frequency discharges of fluorocarbons utilized for plasma etching or polymerization

Optical emission (180–800 nm) and mass spectroscopy have been used to study the CF₄, CF₄+O₂, C₂F₆, C₂F₆+H₂, CF₃Cl, and C₂F₄ decomposition in radio-frequency discharges. The analysis of the stable and unstable discharge products has allowed the suggestion of decomposition channels for the various gases and to classify the fluorinated gases according to their predominant etching or polymerizing characteristics on the basis of the active species present in the plasma. A new broad emission continuum centered at =290 nm (FWHM=66 nm) has also been identified and it has been tentatively assigned to CF⁺ ₂.     

Synthesis of Trinorditerpenoid Derivatives and Evaluation of Antimicrobial and Cytotoxic Activity

The synthesis of optically active trinorditerpenes was carried out, and their antimicrobial and antitumor activity was tested. The synthetic derivative 12-hydroxypodocarpa-8,11,13-triene (7) showed GI₅₀ at 6.6 µM against breast cancer MDA-MB-435 (LC₅₀ = 50.9 µM and log10 GI₅₀ = −5.18). The 12-acetyloxypodocarpa-8,11,13-triene (8) showed GI₅₀ at 12.1 µM against leukemia RPMI-8226 (LC₅₀ = 76.1 µM and log₁₀GI₅₀ = −4.92).__________Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 255–259, May–June, 2005.     

Chemical reactivity of hypervalent silicon compounds: The local hard and soft acids and bases principle viewpoint

The silicon atom may increase its coordination number to values greater than four, to form pentacoordinated compounds. It has been observed experimentally that, in general, pentacoordinated compounds show greater reactivity than tetracoordinated compounds. In this work, density functional theory is used to calculate the global softness and the condensed softness of the silicon atom for SiH _n F_4−n and SiH _n F _5−n ¹⁻ . The values obtained show that the global and condensed softness are greater in the pentacoordinated compounds than in the tetracoordinated compounds, a result that explains the enhanced reactivity. If the results are analysed through a local version of the hard and soft acids and bases principle, it is possible to suggest that in nucleophilic substitution reactions, soft nucleophiles preferably react with SiH _n F _5−n ¹⁻ , and hard nucleophiles with SiH _n F_4−n .     

Donor and acceptor properties of the solvents tetrahydrofuran and tetrahydrothiophene

The donor and acceptor properties of tetrahydrofuran and tetrahydro-thiophene were evaluated by means of electrochemical and spectroscopic methods. Polarographic and cyclovoltammetric data for LiClO₄, NaClO₄, KClO₄, RbClO₄, CsClO₄, Ba(ClO₄)₂, AgCF₃SO₃, TlClO₄, Zn(CF₃SO₃)₂, Cd(CF₃SO₃)₂, Cu(CF₃SO₃)₂, Pb(CF₃SO₃)₂, Mn(CF₃SO₃)₂, Co(CF₃SO₃)₂, Ni(ClO₄)₂·2H₂O, oxygen, perylene, ferrocene, and bis(biphenyl)chromium tetraphenylborate in tetrahydrofuran and of TlClO₄, CuCF₃SO₃, Pb(CF₃SO₃)₂, Cd(CF₃SO₃)₂, oxygen, ferrocene and bis(biphenyl)chromium tetraphenylborate in tetrahydrothiophene together with the potentials of the Ag/0.01 M Ag⁺-ion electrodes in these two solvents are given. Molar Gibbs (free) energies for the transfer from acetonitrile into tetrahydrofuran for Na⁺, K⁺, Rb⁺, Ag⁺, Tl⁺, Zn²⁺, Cd²⁺, and Pb²⁺, and for the transfer into tetrahydrothiophene for Ag⁺, Cu⁺, Tl⁺, Cd²⁺, and Pb²⁺ were calculated from these data. Visible spectra were obtained for the solvatochromic dyes acetylacetonato(N,N,N,N,-tetramethylethylenediamine) copper(II) perchlorate and for 2,6-diphenyl-4-(2,4,6-triphenyl-l-pyridinio)phenoxide, which served as secondary standards to obtain donor and acceptor numbers. The changes in half-wave potentials of the cations vs. bis(biphenyl)chromium(I)/(0) and the Gibbs energies of transfer are discussed on basis of hard and soft donor properties of these two solvents.     

Redox reactions of GeII and SnII dihalides with triethylsilane and triethylgermane

Dihalogermylenes, dihalostannylenes, and their complexes (EI₂, ECl₂·dioxane, and (CO)₅W=ECl₂·THF, where E = Ge or Sn), unlike organylgermylenes, are not inserted at the Si—H (Ge—H) bond of triethylsilane (triethylgermane). The reactions of SnI₂, ECl₂·dioxane, and (CO)₅W=ECl₂·THF (E = Ge or Sn) with Et3E"H (E" = Si or Ge) occur as redox processes. Depending on the nature of the reagents, the reactions afford products of oxidative coupling (Et₃SiSiEt₃) and/or haloiodination (Et₃SiX and Et₃GeX) of triethylsilane (triethylgermane). The proposed mechanism of these reactions involves the electron transfer to form radical-ion pairs.     

Homo- and hetero-dinuclear derivatives of aluminium containing Schiff-base ligands: synthesis,characterization and antibacterial activity of mononuclear derivative of aluminium

Reactions of Al(OPrⁱ)₃ with LH₂ =?[R′C(NYOH)CHC(R)OH] R=R′=CH₃, Y =?(CH₂)₂ (L¹H₂); R =?CH₃, R′ =?C₆H₅, Y =?(CH₂)₂ (L²H₂); R =?R′ =?CH₃, Y =?(CH₂)₃ (L³H₂); R =?CH₃, R′ =?C₆H₅, Y =?(CH₂)₃ (L⁴H₂), in 1 : 2 molar ratio give mononuclear derivatives of aluminium AlLLH (1a–1d). Equimolar reactions of AlLLH with M(OPrⁱ)₃ (M =?Al and B) yield homo- and hetero-dinuclear derivatives AlLLM(OPrⁱ)₂ (M=Al=2a–2d M=B=3a–3d). Reaction of 2a with L¹H₂ affords AlL¹L¹AlL¹ (4). All these derivatives have been characterized by elemental analysis, molecular weight measurements and plausible structures have been suggested on the basis of IR, NMR [¹H, ¹³C, ²⁷Al and ¹¹B] spectral data and FAB-mass studies of 2b and 3b. Schiff base L¹H₂ and its mononuclear derivative with aluminium (AlL¹L¹H) have been screened for their antibacterial activity against Escherischia coli and Bacillus subtilis.     

Synthesis,characterization and biological activity of triaminoxime and its metal complexes

Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of multifunctional triaminoxime have been synthesized and characterized by elemental analyses, IR, UV–Vis spectra, magnetic moments, ¹H- and ¹³C-NMR spectra for ligand and its Ni(II) complex, mass spectra, molar conductances, thermal analyses (DTA, DTG and TG) and ESR measurements. The IR spectral data show that the ligand is bi-basic or tri-basic tetradentate towards the metals. Molar conductances in DMF indicate that the complexes are non-electrolytes. The ESR spectra of solid copper(II) complexes [(HL)(Cu)₂(Cl)₂] · 2H₂O (2) and [(L)(Cu)₃(OH)₃(H₂O)₆] · 7H₂O (6) show axial symmetry of a d _{x²???y ²} ground state; however, [(HL)(Co)] (4) shows an axial type with d _Z ² ground state and manganese(II) complex [(L)(Mn)₃(OH)₃(H₂O)6] · 4H₂O (10) shows an isotropic type. The biological activity of the ligand and its metal complexes are discussed.     

Syntheses of novel delocalized cations and fluorinated anions,new fluorinated solvents and additives for lithium ion batteries

To improve the properties of rechargeable lithium ion batteries, like conductivity, SEI-formation, thermal and electrochemical stability, low and high temperature performance and safety new electrolyte salts, novel solvents (co-solvents) and additives have been synthesized. All new anions, solvents and additives contain fluorine proving the importance of this element for the electrolyte system. Tetrafluoroborates having bulky delocalized nitrogen-, phosphorus and sulfur-centered counter-cations containing tetramethylguanidyl substituents, like [(Me₂N)₂CNC(NMe₂)₂]⁺, have been prepared to improve the conductivity in polymer electrolytes. The hitherto unknown lithium sulfonate, MeOCF₂CF₂SO₃Li, has been successfully synthesized along with further analogs, and also MeOCF₂CF(CF₃)SO₃Li was obtained, both from precursors, FO₂SCF₂C(O)F or FO₂SCF(CF₃)C(O)F accessible by ring opening reactions from the respective sultones. For the lithium salt CF₃OCF(CF₃)SO₃Li, a new simple synthetic pathway was found where CF₃OCFCF₂ and SO₂F₂ were used as precursors. Novel possible redox shuttles, namely (CF₃)₅C₆OLi and fluorinated pyridine-N-oxides have been prepared. A neutral cyclic carben-PF₅ adduct turned out to be a very effective overcharge protection additive. The family of cyclic and acyclic carbonates playing a key-role as electrolyte solvents in lithium ion batteries could be extended by derivatives of 1,1,1,4,4,4-hexafluorobutandiol. Reaction products from perfluoropropene oxide and alcohols, ROC(F)CF₃C(O)OR (R = CH₂CF₃, CH₂CH₂, CH(CF₃)₂) were obtained according to new optimized methods. New cyclic sulfonamides synthesized from FO₂SCF₂C(O)F and FO₂SCF(CF₃)C(O)F could be successfully identified as versatile electrolyte additives.     

Pb(II) and Bi(III) complexes involving a Schiff base ligand: syntheses,structures, physical,and antioxidant properties

Two new complexes, {[PbL(NO₃)₂H₂O]H₂O}_n (1) and [BiL₂(NO₃)₂]NO₃ (2), based on (E)-3-chloro-6-[2-(pyrazin-2-ylmethylene)hydrazinyl]pyridazine (L) were synthesized and characterized by IR spectra, single-crystal X-ray diffraction, and elemental analyzes. X-ray single crystal diffraction experiments of 1 and 2 display that extensive hydrogen bonds and π…π stacking interactions construct the 1-D infinite chain {[PbL(NO₃)₂H₂O]H₂O}_n and [BiL₂(NO₃)₂]NO₃ into two 3-D supramolecular frameworks. Interestingly, pure phase PbO nano-particles were synthesized by thermolysis of 1 and characterized by scanning electron microscopy and X-ray powder diffraction analyzes. Furthermore, antioxidant activities of L, 1, and 2 were also studied.