Formation of azatitanacyclopentanes from ene-imines and a Ti(O-i-Pr)4/2i-PrMgX reagent and their synthetic reactions

ω-Vinylimines reacted with a Ti(O-i-Pr)₄/2i-PrMgX reagent to generate the corresponding azatitanacyclopentanes in quantitative yield, which in turn reacted with H₂O, I₂ and O₂ to give 2-methyl-, 2-iodomethyl-, 2-hydroxymethyl-1-aminocyclic compounds, respectively. The azatitanacyclopentanes thus generated reacted with formaldehyde to afford the corresponding 2,3-annulated pyrrolidines in good yield.     

Truly catalytic and enantioselective pinacol coupling of aryl aldehydes mediated by chiral Ti(III) complexes

A variety of chiral Ti(IV) complexes were reduced in situ with zinc in acetonitrile. The resulting chiral Ti(III) complexes were found to catalyze the pinacol coupling reaction stereoselectively. The best results were obtained from the Ti-SALEN complex, which was found to be an efficient catalyst at 10 mol % concentration. Various aromatic aldehydes were coupled to obtain chiral hydrobenzoin derivatives with high diastereoselectivity and enantioselectivity. A plausible mechanism is proposed that rationalizes the stereochemical outcome of the reaction.     

Novel Knöevenagel-type reaction via titanium enolate derived from Ti(O-i-Pr)4 and diketene

Knöevenagel-type reaction between diketene and aldehydes proceeded in the presence of Ti(O-i-Pr)₄. This reaction proceeded via titanium enolate derived from Ti(O-i-Pr)₄ and diketene. As for the stereoselectivity of the products, E-isomers were produced predominantly in the case of aromatic aldehydes.     

A highly regioselective azidolysis of 2,3-epoxy amines: an unexpected [Ti(O-i-Pr)2(N3)2] mediated C-2 opening

The Lewis acid-catalysed regioselective azidolysis of 2,3-epoxy amines has been investigated. The results obtained demonstrated that using TMSN₃ as a source of azide, the appropriate choice of Lewis acid allowed to direct the regiochemistry of the ring opening. The present methodologies provide a powerful tool in organic synthesis for the preparation of diaminoalcohol moieties.     

Use of isopropyl alcohol as a solvent in Ti(O-i-Pr)4-catalyzed Knöevenagel reactions

Knöevenagel reactions of aldehydes and ketones with malononitrile, isopropyl cyanoacetate and diisopropyl malonate catalyzed by Ti(O-i-Pr)₄ proceeded smoothly in i-PrOH to give the corresponding reaction products in good to high yield. 3-Substituted coumarins were prepared by the present method.     

InCl3/Al mediated pinacol coupling reactions of aldehydes and ketones in aqueous media

A systematic work on the homo-pinacol coupling reactions of benzophenones, aldehydes, and acetophenones in aqueous media with InCl₃/Al is described for the first time, in which various 1,2-diols are obtained in moderate to good yields.     

Perfluormethyl-element-liganden : XXXI. Ligandeneigenschaften von Me2PP(CF3)2 und Me2AsP(CF3)2

The coordinating properties of the trifluoromethyl elemental compounds Me₂PP(CF₃)₂ and Me₂AsP(CF₃)₂ have been studied by the synthesis and spectroscopic investigations (IR, NMR, MS) of their complexes cis-M(CO)₄L₂ (A), [(CO)₄ML]₂ (B) and [(CO)₅M]₂L (C) (M = Cr, Mo, W). Complexes of type A with L = Me₂PP(CF₃)₂ are obtained in good yield by reaction with M(CO)₄NBD (NBD = norbornadiene), whereas with L = Me₂AsP(CF₃)₂ the homobinuclear compounds B are formed. The attempt to prepare the cis-M(CO)₄[Me₂AsP(CF₃)₂]₂ complexes by treating M(CO)₄(Me₂AsH)₂ with P₂(CF₃)₄ is successful only for M = W. Binuclear compounds of type B or C, in general, can be prepared by stepwise reaction of the ligands with either M(CO)₄NBD or M(CO)₅THF.     

(CH3)3SiCl/TiCl4 INITIATING SYSTEM FOR CATIONIC POLYMERIZATION OF 1,3-PENTADIENE

Cationic polymerizations of 1,3-pentadiene (PD) initiated by trimethylsilyl chloride (TMSCl) incombination with TiCl_4 were carried out in n-hexane at 30℃. The yield of polymer was greatly increased bythe addition of TMSCl, indicating that the TMSCl/TiCl_4 combination is an efficient initiating system for PDcationic polymerization. However, the introduction of TMSCl gave rise to a drop in the molecular weight ofthe polymer. Kinetic results demonstrated that the polymerization initiated by TMSCl/TiCl_4 is 4.5 times fasterthan that induced by TiCl_4 alone. Various ethers were used to mediate the TMSCl/TiCl_4 initiating system.Adding diphenyl ether could increase both the yield and molecular weight of the polymer. Structural evidenceillustrates that the polymerization is indeed initiated by TiCl_4 in combination with HCl resulting fromhydrolysis by adventitious water.     

Synthesis, molecular structure, and catalytic activity of borohydride complexes [(Me3Si)2NC(NPri)2]2Nd(BH4)2Li(thf)2 and [(Me3Si)2NC(NPri)2]2Sm(BH4)2Li(thf)2

The reactions of lanthanide tris(borohydrides) Ln(BH₄)₃(thf)₃ (Ln = Sm or Nd) with 2 equiv. of lithium N,N′-diisopropyl-N′-bis(trimethylsilyl)guanidinate in toluene produced the [(Me₃Si)₂NC(NPrⁱ)₂]Ln(BH₄)₂Li(thf)₂ complexes (Ln = Sm or Nd), which were isolated in 57 and 42% yields, respectively, by recrystallization from hexane. X-ray diffraction experiments and NMR and IR spectroscopic studies demonstrated that the reactions afford monomeric ate complexes, in which the lanthanide and lithium atoms are linked to each other by two bridging borohydride groups. The complexes exhibit catalytic activity in polymerization of methyl methacrylate. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 441–445, March, 2007.     

Structure of two new borates YCa3(AlO)3(BO3)4 and YCa3(GaO)3(BO3)4

By replacing Mn in YCa₃(MnO)₃(BO₃)₄ with trivalent Al and Ga, two new borates with the compositions of YCa₃(MO)₃(BO₃)₄ (M=Al, Ga) were prepared by solid-state reaction. Structure refinements from X-ray powder diffraction data revealed that both of them are isostructural to gaudefroyite with a hexagonal space group P6₃/m. Cell parameters of a=10.38775(13)Å, c=5.69198(10)Å for the Al-containing compound and a=10.5167(3)Å, c=5.8146(2)Å for the Ga analog were obtained from the refinements. The structure is constituted of AlO₆ or GaO₆ octahedral chains interconnected by BO₃ groups in the ab plane to form a Kagomé-type lattice, leaving trigonal and apatite-like tunnels. It is found that most rare-earth and Cr, Mn ions can be substituted into the Y³⁺ and M³⁺ sites, respectively, and the preference of rare-earth ions to locate in the trigonal tunnel is correlated to the sizes of the M³⁺ ions.     

Enantioselective pinacol coupling of aryl aldehydes catalyzed by chiral Salan-Mo(IV) complexes

Reported herein is the asymmetric pinacol coupling of aromatic aldehydes with chiral Salan-Mo(VI) dioxo complex as an effective precatalyst. Chiral diols were obtained with high diastereoselectivity and enantioselectivity up to 92/8 and 95%, respectively. The possible mechanism of the pinacol coupling reaction with the catalytic system was investigated. The X-ray crystal structure of the precatalyst Mo(L3)O2 was determined and the oxidation state of the intermediate C was confirmed as +4 with X-ray photoelectron spectroscopy study. The proposed mechanism speculated the stereochemical outcome of the reaction, and a working model for the radical coupling of E was proposed, which explained the absolute configuration of the favored (S,S)-enantiomer of the dl isomer.     

Geometrical isomerization of fac/mer-Mo(CO)3(phosphite)3 and cis/trans-Mo(CO)4(phosphite)2 catalyzed by Me3SiOSO2CF3

Geometrical isomerization of fac-Mo(CO)₃L₃ (L = P(OPh)₃, P(OMe)₃, P(OEt)₃) to the mer form and that of cis-Mo(CO)₄L₂ (L = P(OPh)₃, P(OMe)₃, PPh₂(OMe)) to the trans form were observed in CH₂Cl₂ at room temperature in the presence of a catalytic amount of Me₃SiOSO₂CF₃ (TMSOTf). Crossover experiments suggest that a ligand dissociation is not involved in the isomerization. A catalytic cycle involving an interaction of the silicon atom in Me₃Si⁺ with one oxygen in P(OR)₃ ligands has been proposed. The first isolation and the X-ray structure analysis were attained for mer-Mo(CO)₃{P(OPh)₃}₃ through the TSMOTf-assisted isomerization of fac-Mo(CO)₃{P(OPh)₃}₃.     

Darstellung und chemie von Me2TlN(SiMe3)2 und Tl[N(SiMe3)2]3

The complexes [Rh(η³-C₃H₄R)(η⁵-C₅R′₅)L]⁺BF₄^- (R  1-Me, R′  H, Me; R  2-Me, R′  H) (L  C₅H₅N, Ph₃P, Ph₃As) have been prepared from Rh(η³-C₃H₄R)(η⁵-C₅R′₅)Cl and AGBF₄ in acetone, followed by reaction with the stoicheiometric quantity of L. The ¹H and ¹³C NMR spectra of the salts are reported and discussed.     

TiCl(OPr)3 and NaBH(OAc)3: an efficient reagent combination for the reductive amination of aldehydes by electron-deficient amines

Sodium triacetoxyborohydride, NaBH(OAc)₃ with tri-isopropoxytitanium chloride, TiCl(OⁱPr)₃ is a useful reagent combination for reductive amination. Electron-deficient amines and heteroaromatic amines such as 2-aminopyrimidine and 2-aminothiazole can be reductively alkylated at room temperature to afford the corresponding secondary amines in good yields.     

Structures, energy bands and conductivities of (Me3NEt)[Pd(dmit) 2]2 and (NEt4)[Pd(dmit) 2]2

The electrical conductive molecular crystals (Me₃NEt)[Pd(dmit) ₂]₂ and (NEt₄)[Pd (dmit) ₂]₂ (dmit = 4,5-dimercapto-1,3-dithiole-2-thione) have been prepared, and their crystal structures and conductivity-temperature curves have been determined. The fact that the conductivity at room temperature of (Me₃NEt)[Pd(dmit) ₂]₂ (σ = 58 Ω^-1 cm^-1) is much higher than that of (Net₄)-[Pd(dmit)₂]₂ (σ = 2.2 Ω^-1.cm^-1) has been rationally explained by the results of energy band calculations. (MeNEt₃)[Pd(dmit)₂]₂ belongs to monoclinic system, P2₁/m space group and (Net₄)[Pd (dmit)₂]₂ belongs to triclinic system, space group. The structural conducting component of the crystals is the planar coordinative anion [Pd(dmit)₂]^0.5- which forms the face-to-face dimmer. [Pd(dmit)₂]^- ₂These dimers have been further constructed to be a kind of two-dimensional (2-D) conductive molecular sheet by means of S_S intermolecular interactions. The tiny difference of the above 2-D molecular sheets of the two title crystals has resulted in one order of magnitude difference of conductivities.     

Ba3 (VO4)2-K2 Ba(MoO4)2 and Pb3 (VO4)2-K2 Pb(MoO4)2 systems

Phase equilibria in the Ba₃(VO₄)₂-K₂Ba(MoO₄)₂ and Pb3(VO₄)₂-K₂Pb(MoO₄)₂ systems have been investigated. In the first system, a continuous series of substitutional solid solutions with the palmierite structure is formed, and in the second one, the polymorphic transition in lead orthovanadate at 100°C restricts the extent of the palmierite-type solid solution to 10–100 mol % K₂Pb(MoO₄)₂. Original Russian Text ? V.D. Zhuravlev, Yu.A. Velikodnyi, A.S. Vinogradova-Zhabrova, A.P. Tyutyunnik, V.G. Zubkov, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 10, pp. 1746–1748.     

Tetrakis(triphenylphosphine oxide) complexes of the lanthanide nitrates; synthesis, characterisation and crystal structures of [La(Ph3PO)4(NO3)3]·Me2CO and [Lu(Ph3PO)4(NO3)2]NO3

The reaction of Ln(NO₃)₃·6H₂O (Ln=La, Ce, Pr or Nd) with a sixfold excess of Ph₃PO in acetone formed [Ln(Ph₃PO)₄(NO₃)₃]·Me₂CO. The crystal structure of the La complex shows a nine-coordinate metal centre with four phosphine oxides, two bidentate and one monodentate nitrate groups, and PXRD studies show the same structure is present in the other three complexes. In CH₂Cl₂ or Me₂CO solutions, ³¹P NMR studies show that the complexes are essentially completely decomposed into [Ln(Ph₃PO)₃(NO₃)₃] and Ph₃PO. Similar reactions in ethanol gave [Ln(Ph₃PO)₃(NO₃)₃] only. In contrast for Ln=Sm, Eu or Gd, only the [Ln(Ph₃PO)₃(NO₃)₃] are formed from either acetone or ethanol solutions. For the later lanthanides Ln=Tb–Lu, acetone solutions of Ln(NO₃)₃·6H₂O and Ph₃PO gave [Ln(Ph₃PO)₃(NO₃)₃] only, even with a large excess of Ph₃PO, but from cold ethanol [Ln(Ph₃PO)₄(NO₃)₂]NO₃ (Ln=Tb, Ho–Lu) were obtained. The structure of [Lu(Ph₃PO)₄(NO₃)₂]NO₃ shows an eight-coordinate metal centre with four phosphine oxides and two bidentate nitrate groups. In solution in CH₂Cl₂ or Me₂CO the tetrakis-complexes show varying amounts of decomposition into mixtures of [Ln(Ph₃PO)₃(NO₃)₃], [Ln(Ph₃PO)₄(NO₃)₂]NO₃ and Ph₃PO as judged by ³¹P{¹H} NMR spectroscopy. The [Ln(Ph₃PO)₃(NO₃)₃] also partially decompose in solution for Ln=Dy–Lu, forming some tetrakis(phosphine oxide) species.     

Magnetic investigation of Cu(NH3)4(NO3)2

The magnetic properties of Cu(NH₃)₄(NO₃)₂ have been measured at low temperatures. Broad maxima in both the susceptibility and specific heat are observed and are consistent with linear chain behavior of a Heisenberg antiferromagnet, with J/k = 3.9 ± 0.1 K. Long-range order sets in at T_c = 0.15 ± 0.01 K, and the ratio kT_c/|J| = 0.038 is the lowest observed as yet for a one-dimensional, S = 1/2 antiferromagnet.     

Vibrational spectra of the peroxotantalates (NH4)3[Ta(O2)4], K3[Ta(O2)4], Rb3[Ta(O2)4] and Cs3[Ta(O2)4] and the crystal structure of Rb3[Ta(O2)4]

The compounds (NH₄)₃[Ta(O₂)₄], K₃[Ta(O₂)₄], Rb₃[Ta(O₂)₄] and Cs₃[Ta(O₂)₄] have been prepared and investigated by X-ray powder methods as well as Raman- and IR-spectroscopy. In the case of Rb₃[Ta(O₂)₄] the structure has been solved from single crystal data. It is shown that all these compounds are isotypic and crystallize in the K₃[Cr(O₂)₄] type (SG , No. 121). The infrared- and Raman spectra (recorded on powdered samples) are discussed with respect to the internal vibrations of the peroxo-group and the dodecahedral [Ta(O₂)₄]³⁻ ion. Symmetry coordinates for the [Ta(O₂)₄]³⁻ ion are given from which the vibrational modes of the O-O stretching vibrations of the O₂²⁻ groups, the Ta-O stretching vibrations and the Ta-O bending vibrations are deduced.     

用T-jump/FTIR研究MnCP、NiCP和PbCP的快速热分解(英)

0IntroductionCarbohydrazideisahydrazinederivativewithwhitecrystalofstrongreducingbehaviors.Becauseithasmanycoordinationatoms(fournitrogenatomsandoneoxygenatom),carbohydrazidecan,therefore,beusedasmultidentateligand.Itscoordinationcom鄄poundiswidelyusedint…