Lutetium complexes with the 1,3-diphenylcyclopentadienyl ligand. Syntheses and molecular structures of the complexes {(Ph2C5H3)Lu(C2Ph4)(THF)} and {(Ph2C5H3)LuCl2(THF)3}

The reaction of LuCl₃(THF)₃ with Na(1,3-Ph₂C₅H₃) followed by the in situ reaction with Na₂[Ph₄C₂] produced (1,3-Ph₂C₅H₃)Lu(Ph₄C₂)(THF) (1). The structure of 1 was established by X-ray diffraction. In the crystal structure of 1, the bis-allyl η⁶-coordination of the tetraphenylethylene dianion to the lutetium cation was observed. The structures of (1,3-Ph₂C₅H₃)LuCl₂(THF)₃ and (C₅H₅)LuCl₂(THF)₃ were determined by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1912–1918, October, 2007.     

Catalytic hydrogenation of 1,3-trans-pentadiene over Rh4(CO)12 supported on γ-Al2O3

Rh₄(CO)₁₂ anchored on γ-Al₂O₃ (Rh₄(CO)₁₂/Al₂O₃) has been studied as a catalyst for the hydrogenation of 1,3-trans-pentadiene. Under mild conditions (1 atm H₂ and temperatures between 60°C and 80°C) hydrogenation occurs at only one of the double bonds of the diene, and analysis of the products shows that the terminal double bond is preferentially hydrogenated. Hydrogenation of the second double bond of the conjugated diene occurring only after all the 1,3-trans-pentadiene has been consumed. In this respect Rh₄(CO)₁₂/Al₂O₃ behaves like toluene solutions of Rh₄(CO)₁₂. Anchoring of Rh₄(CO)₁₂ on the solid support gives a catalyst which is less active but more stable than toluene solutions of Rh₄(CO)₁₂. The effects of CO and of triphenylphosphine on catalytic activity and on specificity of Rh₄(CO)₁₂/Al₂O₃ have also been investigated and both shown to cause a reduction of the rate of hydrogenation of 1,3-trans-pentadiene.     

Molecular structures of (SiCl3)2CH2 and (SiCl3)2CCl2 as studied by electron diffraction

An electron diffraction analysis of the molecular structures of 1,1,1,3,3,3-hexachloro-1,3-disilapropane and octachloro-1,3-disilapropane has been carried out. Deviations from the staggered conformation are indicated. The data may be approximated by models with C₂ symmetry and a small tilt of the SiCl₃ groups. The main bond lengths (r_g) and bond angles obtained for (SiCl₃)₂ CH₂ are: SiCl, 202.7(4); SiC, 186.6(6); CH, 109.8(24) pm, ClSiCl, 107.9(1); SiCSi, 118.3(7)°; and for (SiCl₃)₂CCl₂: SiCl, 202.0(4); SiC, 190.2(9); CCl, 179.6(9) pm; ClSiCl, 109.5(1); SiCSi, 120.6(9); ClCCl, 110.9(16); SiCCl, 106.3(3)°.     

The preparation and properties of some allyltin carboxylates:R3SnOOCR′ (R′ = CH3, CH2Cl), R2Sn(OOCR′)2 (R′ = CH2Cl,CHCl2) and [R2Sn(OOCR′)]2O (R′ = CH2Cl,CHCl2, CCl3)

Triallyl- and diallyltin carboxylates [(CH₂CHCH₂)₃SnOOCR′ with R′ = CH₃ and CH₂Cl, (CH₂CHCH₂)₂Sn(OOCR′)₂ with R′ = CH₂Cl and CHCl₂)] and tetraallyl-1,3-diacyloxydistannoxanes {[(CH₂CHCH₂)₂SnOOCR′]₂ with R′ = CH₂Cl,CHCl₂ and CCl₃}, have been prepared from the reaction of tetraallytin with carboxylic acids in methanol.     

The structure and dynamic behaviour in solution of the trihydridodienerhenium complexes (Ph3P)2(η-1,3-diene)ReH3

The structure and fluxionality of the trihydridodiene complexes (Ph₃P)₂(η-1,3-<di-ene)ReH₃ have been studied by NMR spectroscopy (η-1-3-diene = buta-1,3-diene, 2-methylbuta-1,3-diene, 2,3-dimethylbuta-1,3-diene, cyclohexa-1,3-diene, penta-1,3-diene, hexa-1,3-diene and hexa-2,4-diene). Several rearrangement processes have been observed; they are, in order of increasing temperature: (a) ligand interchange; (b) reversible migration of a hydride ligand on to the diene ligand, leading to η-allyl species and, in the case of the cyclohexadiene trihydride, degenerate isomerisation of the cyclohexadiene moiety; and (c), in the case of the pentadiene and hexadiene derivatives, isomerisation of the diene ligand.     

Application of Et3NHCl-AlCl3 ionic liquid as an initiator in cationic copolymerization of 1,3-pentadiene with styrene

Cationic copolymerization of 1,3-pentadiene (PD) with styrene (St) using the triethylamine hydrochloride-aluminium chloride (Et₃NHCl-AlCl₃) room temperature ionic liquid as an initiator in toluene has been investigated. The polymerization proceeds to high conversions, indicating high initiating reactivity of Et₃NHCl-AlCl₃ in these copolymerization systems, although molecular weights of the polymers are limited which are similar to polymerization initiated by Lewis acids such as TiCl₄, BF₃, BF₃·OEt₂. The polymers were analyzed using IR spectra in conjunction with gel permeation chromatography (GPC).     

Crystal structure of [Cs2Na(H2O)2(C23H16O3)(C23H15O3)3]

The crystal structure of a double salt of sodium and cesium with 2-diphenylacetyl-1,3-indandione of the composition [Cs₂Na(H₂O)₂(C₂₃H₁₆O₃)(C₂₃H₁₅O₃)₃] (I) was studied by X-ray crystallography. The crystals of I are monoclinic, Z = 2, space group P2₁/n, a = 10.212(2) ?, b = 23.479(5) ?, c = 15.638(3) ?, β = 98.30(03)°. The compound contains [Cs₂NaO₁₀] trimers, in which the central Na atom shares two edges with two Cs atoms through deprotonated bridging ligands. The trimers are connected to adjacent trimers by paired C-H...O contacts to form layers. The layers form an infinite open framework via hydrogen bonds between the oxygen atoms of keto groups of noncoordinated indandione moieties and water molecules that enter the cesium coordination sphere in trimers of the adjacent layers.     

Efficient and selective hydroarylation of propiolic acids and their esters with arenes catalyzed by a PtCl2/AgOTf system

PtCl₂/AgOTf-catalyzed hydroarylation of ethyl propiolate proceeded effectively to give ethyl (2Z)-cinnamate derivatives in good to high yields, without the formation of diethyl (1E,3Z)-4-arylbuta-1,3-diene-1,3-dicarboxylates that was observed in Pd(OAc)₂-catalyzed reaction. Especially, PtCl₂/AgOTf-catalyzed hydroarylation of propiolic acids proceeded effectively to give (2Z)-cinnamic acids exclusively.     

Alkylation of nitrogen heterocycles with 1,3-bis(hydroxymethyl)ferrocene. Generation of the ferrocene dicarbocation [{1,3-(CH2)2C5H3}Fe(C5H5)]2+

The alkylation of imidazole and 5-benzyloxycarbonyl-3,4-diethylpyrrole with 1,3-bis-(hydroxymethyl)ferrocene (1) afforded bis-imidazole (4) and bis-pyrrole (7) derivatives of ferrocene, respectively. The reaction of diol 1 with trifluoroacetic acid gave the dicarbocationic complex [{1,3-(CH₂)₂C₅H₃}Fe(C₅H₅)]²⁺ (2) characterized by ¹H NMR spectroscopy.     

Stereoselective synthesis of anti-2-oxazolidinones by Ph3P-CCl4-Et3N mediated SN2 cyclization of N-Boc-β-amino alcohols

Ethyl anti-4-substituted phenyl-2-oxo-1,3-oxazolidine-5-carboxylates were synthesized stereoselectively in excellent yields using the Ph₃P-CCl₄-Et₃N system by S_N2 cyclization of N-Boc-β-amino alcohols. syn to anti conversion of ethyl 4-substituted phenyl-2-oxo-1,3-oxazolidine-5-carboxylates using DBU as base is also described.     

Phosphorus heterocycle synthesis by RPX2,· AlX3 addition to [1,n]dienes VII.

The RPX₂·AlX₃ complex ($\text{1}$) reacts with unsaturated ketones and imines to give novel 7-oxa and 7-aza-2-phosphabicyclo[2.2.1]heptanes (compounds $\text{3}$ and $\text{6}$ respectively).A new 1,3-dipolar addition of (CH₃)₂ CCH₂P?XR to nArN=C=S was disclosed resulting in the formation of the 2-imino-1,3-thiaphospholanes ($\text{7}$).     

The Fermi doublet V2−V3 + V4 of CH3CN as a probe of molecular interactions

The Fermi doublet V₂?V₃ + V₄ of CH₃CN in basic, inert and acidic solvents has been studied by IR and Raman spectroscopy. The values of W, the Fermi coupling coefficient, obtained from IR spectra varies with the nature of the solvent while W evaluated from Raman data remains constant at 12.5 ± 0.5 cm^?1. The similar effects of Bronsted and Lewis acids on the band frequencies and intensities is evidence that the CN group complexes with acids via the N atom “n” electron pair and not the π bond.     

Crystal structures of [Rh(η-C5H5)(C3S5)] and [Rh(η-C5Me5)(C3S5)]2 and properties of their oxidized species

[Rh(η⁵-C₅H₅)(C₃S₅)] and [Rh(η⁵-C₅Me₅)(C₃S₅)]₂ [C₃S₅²⁻=4,5-disulfanyl-1,3-dithiole-2-thionate(2-)] were prepared by reactions of [NMe₄]₂[C₃S₅] with [Rh(η⁵-C₅H₅)Cl₂]₂ and [Rh(η⁵-C₅Me₅)Cl₂]₂, respectively. Their X-ray crystal structural analyses revealed a monomeric form for the former complex and a dimeric geometry containing bridging S-Rh-S bonds for the latter in the solid state. They were reacted with bromine to afford [RhBr(L)(C₃S₅)] (L=η⁵-C₅H₅ and η⁵-C₅Me₅) with the Rh-Br bond and one electron-oxidation on the C₃S₅ ligand. ESR spectra and spin densities for these oxidized species are discussed.     

Ketene organoelement derivatives. Synthesis of bis(l-R-2-oxovinyl)silanes and germanes (R = SiMe3, GeMe3, SnMe3)

Earlier unknown 1,3-bisketene organoelement derivatives RMeE(C(E ’Me₃)=C=O)₂ (E = Si, Ge; E’ = Si, Ge, Sn) have been synthesized by the reaction of bis(alkoxyethynyl)silanes and -germanes with Me₃E’Hal. Bis(1-trimethylsilyl-2-oxovinyl)silane is also formed by the reaction of trimethylsilyl- and (dimethylsilylene)bisketenes with dimethylsilylene bistriflate and trimethylsilyl triflate, respectively. Addition of nucleophiles to the ketene fragment of compounds synthesized has been studied.     

Non-centrosymmetric Ba3Ti3O6(BO3)2

The compound previously reported as Ba₂Ti₂B₂O₉ has been reformulated as Ba₃Ti₃B₂O₁₂, or Ba₃Ti₃O₆(BO₃)₂, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO₃:BaTiB₂O₆ (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F²)=0.039 for 504 unique reflections. Ba₃Ti₃O₆(BO₃)₂ is isostructural with K₃Ta₃O₆(BO₃)₂. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba₃Ti₃O₆(BO₃)₂ is equal to 95% of that of LiNbO₃.     

Thermal decomposition of organo-bielemental vanadium compounds Cp2V(ER3) (ER3 - GeEt3, SnEt3, CH2SiMe3 SeGeEt3)

The thermal decompositon of a number of organo-bielemental vanadium compounds with the general formula Cp₂V(ER₃) (ER₃ - GeEt₃, SnEt₃, CH₂SiMe₃, SeGeEt₃) has been investigated in solids and in solution. The main decomposition products of Cp₂V(SnEt₃) are vanadocene and hexaethyldistannane. Et₃GeH, Et₃GeCp, Cp₂V and CpV(C₅H₄GeEt₃) are formed from Cp₂V (GeET₃) decomposition. Isolated CpV(C₅H₄GeEt₃) is characterized by IR and mass spectra. The decomposition of Cp₂V(CH₂SiMe₃) is accompanied by Me₄Si, Cp₂V and CpV-(C₅H₄CH₂SiMe₃) formation, the latter is identified from the mass spectrum. Triethylgermane, vanadocene, and a diselenide of vanadium are isolated on decomposition of Cp₂V(SeGeEt₃). Based upon the experimental data, mechanisms for the decompositon are proposed.     

Sm2O3Ga2O3 and Gd2O3Ga2O3 phase diagrams

Four definite compounds exist in the Sm₂O₃Ga₂O₃ binary phase diagram, namely: Sm₃GaO₆, Sm₄Ga₂O₉, SmGaO₃, and Sm₃Ga₅O₁₂. The $\text{3}\text{1}$ compound is orthorhombic (space group Pnna - Z.4) with the cell parameters: a = 11.40₀Å, b = 5.51₅Å, c = 9.07Å and belongs to the oxysel family. Sm₃GaO₆ and SmGaO₃ melt incongruently at 1715 and 1565°C; Sm₄Ga₂O₉ and Sm₃Ga₅O₁₂ have a congruent melting point at 1710 and 1655°C. With regard to the Gd₂O₃Ga₂O₃ system three definite compounds have been identified: Gd₃GaO₆, Gd₄Ga₂O₉, and Gd₃Ga₅O₁₂. Only the garnet melts congruently at 1740°C with the following composition: Gd_3.12Ga_4.88O₁₂. Gd₃GaO₆, and Gd₄Ga₂O₉ melt incongruently at 1760 and 1700°C. GdGaO₃ is only obtained by melt overheating which may yield an equilibrium or a metastable phase diagram.     

Iron carbonyl complexes of 2,3,5,6-tetrakis(methylene)-7-oxabicyclo[2.2.1]heptane. Crystal and molecular structure of (C10H10O)Fe(CO)3 and (C9H10CO)Fe2(CO)6

The reaction of 2,3,5,6-tetrakis(methylene)-7-oxabicyclo[2.2.1]heptane (I) with iron carbonyls in various solvents yields the (η⁴-1,3-diene)Fe(CO)₃ isomers (II: exo; III: endo) and the bimetallic isomers bis[(η⁴-1,3-diene)Fe(CO)₃] (IV: bis(exo); V: endo,exo). In weakly coordinating solvents, a parallel rearrangement of I occurs through CO bond cleavage of the allylic ether by Fe₂(CO)₉ yielding an unsaturated ketone (VI) bonded to two Fe(CO)₃ groups through a trimethylenemethane and a 1,3-diene system, respectively. The geometries of III and VI have been ascertained by X-ray crystal structure determinations.     

Synthesis and characterisation of HRuRh3(CO)12. Crystal structures of HRuRh3(CO)12, HRuRh3(CO)10(PPh3)2 and HRuCo3(CO)10(PPh3)2

A new ruthenium-rhodium mixed-metal cluster HRuRh₃(CO)₁₂ and its derivatives HRuRh₃(CO)₁₀(PPh₃)₂ and HRuCo₃(CO)₁₀(PPh₃)₂ have been synthesized and characterized. The following crystal and molecular structures are reported: HRuRh₃(CO)₁₂: monoclinic, space group P2₁/c, a 9.230(4), b 11.790(5), c 17.124(9) Å, β 91.29(4)°, Z = 4; HRuRh₃(CO)₁₀(PPh₃)₂·C₆H₁₄: triclinic, space group P$\text{1}$, a 11.777(2), b 14.079(2), c 17.010(2) Å, α 86.99(1), β 76.91(1), γ 72.49(1)°, Z = 2; HRuCo₃(CO)₁₀(PPh₃)₂·CH₂Cl₂: triclinic, space group P$\text{1}$, a 11.577(7), b 13.729(7), c 16.777(10) Å, α 81.39(4), β 77.84(5), γ 65.56°, Z = 2. The reaction between Rh(CO)₄^? and (Ru(CO)₃Cl₂)₂ tetrahydrofuran followed by acid treatment yields HRuRh₃(CO)₁₂ in high yield. Its structural analysis was complicated by a 80–20% packing disorder. More detailed structural data were obtained from the fully ordered structure of HRuRh₃(CO)₁₀(PPh₃)₂, which is closely related to HRuCo₃(CO)₁₀(PPh₃)₂ and HFeCo₃(CO)₁₀(PPh₃)₂. The phosphines are axially coordinated.     

Formation of C4 Oligomers in Hydrogenation of Acetylene over Pd/Al2O3 and Pd/TiO2 Catalysts

Selectivity of product formation has been tested in hydrogenation of acetylene over 0.3 wt.% Pd/-alumina and 0.5 wt.% Pd/TiO₂catalysts. Non-steady-state regime of catalyst operation was tested in pulse-flow experiments. Significant carbon poisoning appears to be a necessaryrequisite for selective formation of ethylene. The effect of hydrogen and acetylene partial pressure has been tested on the selectivity of C₄products. At 273–298 K the catalysts showed 26–35% selectivity for C₄ hydrocarbons and <2.5% for ethane production at conversionsof 30–40%. Deuterium distribution in ethylene and 1,3-butadiene and the deuterium content of the surface hydrogen pool have been compared and mechanismof diene formation has been discussed.