Efficient homo-coupling reactions of heterocyclic aromatic bromides catalyzed by Pd(OAc)2 using indium

Homo-coupling reactions of heterocyclic aromatic bromides smoothly proceeded with cat-Pd(OAc)₂, indium, and LiCl in DMF to afford exclusively symmetric biaryls possessing heterocyclic aromatic ring in good to excellent yields.     

Luminescent silver nitrate complexes of bis[2-(diphenylphosphano)phenyl]ether (DPEphos): Crystal structure of [Ag(DPEphos)(py2SH)2]NO3

Heteroleptic silver(I) nitrate complexes containing the bis[2-(diphenylphosphano)phenyl]ether (DPEphos) ligand and the heterocyclic thioamides pyridine-2(1H)-thione (py2SH), pyrimidine-2(1H)-thione (pymtH), 4,6-dimethylpyrimidine-2(1H)-thione (dmpymtH), 1,4,5,6-tetrahydropyrimidine-2-thione (thpymtH) or 1,3-imidazolidine-2-thione (imtH₂) have been synthesized and characterized by IR and UV-Vis spectroscopy, elemental analyses and melting point determinations. The complexes can be obtained by the addition of the thioamide ligand to an AgNO₃-diphosphane adduct in dichloromethane/ethanol solution. The molecular structure of [Ag(DPEphos)(py2SH)₂]NO₃ complex has been established by single-crystal X-ray diffraction. The structure features a tetrahedral silver(I) center with two phosphorus atoms from the chelating diphos ligand, and the exocyclic sulfur atom of two heterocyclic thioamide units. Intense blue-green emission is observed in the region 470-483 nm for all the complexes in the solid state and in solution at ambient temperature.     

Preparation of dinitrogen complexes Mo(N2)2P4 stabilised by phosphonite PPh(OEt)2 and phosphinite PPh2(OEt) ligands

Dinitrogen complexes Mo(N₂)₂P₄1, 2 [P=PPh(OEt)₂ and PPh₂OEt] were prepared by allowing a MoCl₃(THF)₃ solution containing an excess of phosphine to react with magnesium under nitrogen. Substitution reactions with CO and p-tolylisocyanide were studied, and led to Mo(CO)₂P₄, Mo(CO)₃P₃, and Mo(p-tolylNC)₂P₄ derivatives. Treatment of dinitrogen compound Mo(N₂)₂[PPh(OEt)₂]₄ with an excess of HCl gave the hydrazido(2-) [MoCl(NNH₂){PPh(OEt)₂}₄]Cl derivative. Reduction reactions with zinc amalgam of complexes 1 and 2 in the presence of lutidine·HCl gave ammonia in about 8-10% yield.     

A large series of isotypic Mo(V) diphosphates with a tunnel structure: From A(MoO)10(P2O7)8 with A=Ba, Sr, Ca, Cd, Pb to A(MoO)5(P2O7)4 with A=Ag, Li, Na, K

The single crystal structure of a series of nine isotypic Mo(V) diphosphates was determined from crystals with composition A²⁺(MoO)₁₀(P₂O₇)₈ (A=Ba, Sr, Ca, Cd, Pb) and A⁺(MoO)₅(P₂O₇)₄ (A=Ag, Li, Na, K). The structure of those phosphates, built up of corner sharing MoO₆ octahedra, MoO₅ tetragonal pyramids and P₂O₇ diphosphates groups, forms eight-sided tunnels as described by Lii et al. for A=Ag. New features are evidenced: (1) existence of two orientations, up and down along b for the MoO₅ pyramids; (2) maximum insertion rate of the divalent cations which is twice less than that of the univalent cations; (3) different behavior of the series “Pb, Sr, Ba, Li, Na, K” which exhibits only one kind of site for the inserted cation, compared to the “Cd, Ca, Ag” series for which two kinds of sites are observed; (4) off-centering of the A-site cations with respect to the tunnel axis; and (5) unusually high thermal factors along the tunnel axis, but absence of ionic conductivity.     

Molybdenum and tungsten complexes of the neutral tripod ligands HC(pz)3 and MeC(CH2PPh2)3

Starting from [M(CO)₆], seven-coordinated complexes of tungsten and molybdenum containing the facially coordinating ligands HC(pz)₃ (1) and MeC(CH₂PPh₂)₃ (2) were obtained in a two-step reaction sequence. The complexes have a 4:3 piano stool geometry with almost perfect C_S symmetry in the crystal. In solution, they show the typical fluxional behavior for seven-coordinated complexes even at low temperature. Complete oxidative decarbonylation occurs when [HC(pz)₃Mo(CO)₃] (4) or [MeC(CH₂PPh₂)₃Mo(CO)₃] (6) are treated with an excess of I₂ or Br₂.     

Two mixed valent molybdenophosphates with a tunnel structure closely related to K0.17MoP2O7: Pb2(PbO)2Mo8(P2O7)8 and PbK2Mo8(P2O7)8

Two new mixed valent Mo(III)/Mo(IV) diphosphates containing lead Pb₂(PbO)₂Mo₈(P₂O₇)₈ and PbK₂Mo₈(P₂O₇)₈ have been synthesized. The [Mo₈P₁₆O₅₆]∞ frameworks of these phosphates are closely related to that of K_0.17MoP₂O₇: the MoO₆ octahedra and P₂O₇ groups form two sorts of large eight-sided tunnels. They are occupied in an ordered way by PbO chains and Pb²⁺ cations in Pb₂(PbO)₂Mo₈(P₂O₇)₈ and by K⁺ and Pb²⁺ cations in PbK₂Mo₈(P₂O₇)₈. It results in different symmetries of these two structures, which are tetragonal and monoclinic, respectively, showing the great flexibility of these mixed frameworks, susceptible to accommodate various species with different sizes.     

Efficient solvent-free aminolysis of epoxides under (C4H12N2)2[BiCl6]Cl·H2O catalysis

An efficient and rapid procedure for ring opening of various epoxides with aromatic, aliphatic and heterocyclic amines is developed at room temperature under solvent-free conditions in the presence of (C₄H₁₂N₂)₂[BiCl₆]Cl·H₂O (1 mol %). This catalyst can be reused several times without losing of its activity.     

A novel Mo(V) oligophosphate built up of di- and triphosphate groups: Cs(MoO)4(P2O7)2(P3O10)

A Mo(V) oligophosphate, built up of di and triphosphate groups, Cs(MoO)₄(P₂O₇)₂(P₃O₁₀) has been synthesized for the first time. This compound crystallizes in the triclinic P−1 space group with , , , α=94.534(6)°, β=102.520(6)°, γ=103.663(4)°. This original structure can be described by the association of MoO₆ octahedra, MoP₂O₁₁ units built up of one P₂O₇ group sharing two apices with the same MoO₆ octahedron, and triphosphates groups P₃O₁₀. The resulting tridimensional framework forms large S-shaped tunnels running along c where the Cs⁺ cations are located.     

The CO and CS bond cleavage in carbon dioxide and tolyl isothiocyanate by reactions with the Mo(0) tetraphosphine complex [Mo{meso-o-C6H4(PPhCH2CH2PPh2)2}(Ph2PCH2CH2PPh2)]

A Mo(0) complex containing a new tetraphosphine ligand [Mo(P₄)(dppe)] (1; P₄ = meso-o-C₆H₄(PPhCH₂CH₂PPh₂)₂, dppe = Ph₂PCH₂CH₂PPh₂) reacted with CO₂ (1 atm) at 60 °C in benzene to give a Mo(0) carbonyl complex fac-[Mo(CO)(η³-P₄O)(dppe)] (2), where the O abstraction from CO₂ by one terminal P atom in P₄ takes place to give the dangling P(O)Ph₂ moiety together with the coordinated CO. On the other hand, reaction of 1 with TolNCS (Tol = m-MeC₆H₄) in benzene at 60 °C resulted in the incorporation of three TolNCS molecules to the Mo center, forming a Mo(0) isocyanide-isothiocyanate complex trans,mer-[Mo(TolNC)₂(η²-TolNCS)(η³-P₄S)] (4), where the S abstraction occurs from two TolNCS molecules by P₄ and dppe to give the η³-P₄S ligand and free dppeS, respectively, together with two coordinated TolNC molecules. The remaining site of the Mo center is occupied by the third TolNCS ligating at the CS bond in an η²-manner. The X-ray analysis has been undertaken to determine the detailed structures for 2 and 4.     

Reactions of the cycloheptatrienyl complexes [MX(CO)2(η-C7H7)] (M=Mo, X=Br; M=W, X=I) with CNBu: X-ray crystal structure of [WI(CO)2(CNBu)2(η-C7H7)]

Reaction of [MX(CO)₂(η⁷-C₇H₇)] (M=Mo, X=Br; M=W, X=I) with two equivalents of CNBu^t in toluene affords the trihapto-bonded cycloheptatrienyl complexes [MX(CO)₂(CNBu^t)₂(η³-C₇H₇)] (1, M=Mo, X=Br; 2, M=W, X=I). The X-ray crystal structure of 2 reveals a pseudo-octahedral molecular geometry with an asymmetric ligand arrangement at tungsten in which one CNBu^t is located trans to the η³-C₇H₇ ring. Treatment of 2 with tetracyanoethene results in 1,4-cycloaddition at the η³-C₇H₇ ring to give [WI(CO)₂(CNBu^t)₂{η³-C₉H₇(CN)₄}], 3. The principal reaction type of the molybdenum complex 1 is loss of carbonyl and bromide ligands to afford substituted products [MoBr(CNBu^t)₂(η⁷-C₇H₇)] 4 or [Mo(CO)(CNBu^t)₂(η⁷-C₇H₇)]Br. Reaction of [MoBr(CO)₂(η⁷-C₇H₇)] with one equivalent of CNBu^t in toluene at 60°C affords [MoBr(CO)(CNBu^t)(η⁷-C₇H₇)], 5, which is a precursor to [Mo(CO)(CNBu^t)(NCMe)(η⁷-C₇H₇)][BF₄], 6, by reaction with Ag[BF₄] in acetonitrile. In contrast with the parent dicarbonyl systems [MoX(CO)₂(η⁷-C₇H₇)], complexes of the Mo(CO)(CNBu^t)(η⁷-C₇H₇) auxiliary, 5 and 6, do not afford observable η³-C₇H₇ products by ligand addition at the molybdenum centre.     

Lanthanide (III) addition of [Mo2O3S(HNTA)2] (Ln=Eu, Dy)

The reactions of LnCl₃·6H₂O (Ln=Eu or Dy) and Na₂[Mo₂O₃S(HNTA)₂]·6H₂O afford Na[Mo₂O₃S(HNTA)₂]₂·Eu(H₂O)₉·3H₂O (1) (NTA=nitrilotriacetate) and Na{(H₂O)₆Dy[Mo₂O₃S(HNTA)₂]₂}·7.5H₂O (2), respectively. The [Mo₂O₃S(HNTA)₂]²⁻ cluster units of 1 are interconnected by Na⁺ into a 3-D open framework with rutile topology templated by . The coordination of [Mo₂O₃S(HNTA)₂]²⁻ to the slightly smaller Dy³⁺ ion of greater ionic potential as a consequence of lanthanide contraction has been observed to form the pentanuclear heterometallic {Dy(H₂O)₆[Mo₂O₃S(HNTA)₂]₂}⁻, which is linked by Na⁺ and hydrogen bonds between the protonated carboxylate groups into a 3-D supramolecular framework. The weak antiferromagnetic interactions between the Dy³⁺ ions of 2 have been observed.     

Synthesis and dynamic nuclear magnetic resonance studies of the heterocyclic diphosphacyclopolysilanes, (PhP)2(SiMe2)n. Crystal and molecular structure of (PhP)2(SiMe2)3

The heterocyclic diphosphasilanes (PhP)₂(SiMe₂)_n(n - 2, 3, 4) were synthesized by the reactions of 1, 2-dilithium-1, 2-diphenyldiphosphide with α, ω-dichloropermethylpolysilanes Cl(SiMe₂)_nCl (n - 2, 3, 4). Stereochemical fluxionality in these compounds was examined by dynamic nuclear magnetic resonance. The¹H, ¹³C, ³¹P and²⁹Si NMR spectra are reported and discussed in terms of a phosphorus inversion mechanism. Values of the free energy of activation for phosphorous inversion are reported for (PhP)₂(SiMe₂)_n (n - 3, 4) and compared with related compounds.A single-crystal X-ray structure analysis has been carried out on (PhP)₂-(SiMe₂)₃. The material crystallizes in the monoclinic space groupP2_1/c with four molecules per unit cell. The cell dimensions area - 12.526(11)A?, b - 11.828(10)A?, c - 15.412(7)A?and β - 103.56(6)°. The molecule exists in thedl (trans) form with the five-membered ring significantly twisted. The angle between the phosphorus-phosphorus bond and the plane of the three silicon atoms is 42.9°.     

乙醇辅助的化学沉积法制备硫化型Mo/γ-Al2O3加氢脱硫催化剂

以硫代乙酰胺为硫源,钼酸钠为钼源,乙醇为分散剂,采用化学沉积法制备了MoS₃/Al₂O₃催化剂前驱体,再用H₂高温处理得到高分散硫化型MoS₂/γ-Al₂O₃催化剂,运用N₂吸附-脱附、X射线光电子能谱以及高分辨透射电子显微镜等技术对MoS₂/γ-Al₂O₃催化剂进行了表征,并以二苯并噻吩作为模型化合物评价了催化剂的加氢脱硫(HDS)活性.结果表明,与浸渍法相比,所制催化剂具有更大的比表面积和孔体积、更高的活性金属分散度、更佳的Mo物种硫化度以及更短的MoS₂片层长度和更高的堆积度,因而在二苯并噻吩HDS反应中表现出远优于浸渍法所制催化剂的活性.乙醇可通过S?H-O氢键吸附至MoS₃纳米粒子表面,可有效防止其生长和团聚,起到分散剂的作用.     

Crystal structures of phosphomolybdyl salts: Pb(MoO2)2(PO4)2 and Ba(MoO2)2(PO4)2

Crystal structures of Pb(MoO₂)₂(PO₄)₂ and Ba(MoO₂)₂(PO₄)₂ were determined. Both compounds contain the molybdyl group MoO₂. The monoclinic unit-cell parameters are a = 6.353(7), b = 12.289(4), c = 11.800 Å, β = 92°56(6), and Z = 4 for the lead salt and a = 6.383(8), b = 7.142(7), c = 9.953(8) Å, β = 95°46(8), and Z = 2 for the barium salt. $\text{P2}{}_1\text{c}$ is the common space group. The R values are respectively R = 0.027 and R = 0.031 for 1964 and 1714 independent reflections. The frameworks built up by a three-dimensional network of monophosphate PO₄ and molybdyl MoO₂ groups are similar, characterized mainly by corner-sharing PO₄ and MoO₆ polyhedra. Two oxygen atoms of each MoO₆ group are bonded to the molybdenum atom only as in other molybdyl salts.     

Allylstannation of α-, β- and γ-diketones mediated by allylbutyltin halides: Bu2(CH2=CHCH2) SnCl and Bu(CH2 =CHCH2) SnCl2

Butane-2,3- (1a), pentane-2,4- (1b) and hexane-2,5-dione (1c) react with Bu₂(CH₂=CHCH₂)SnCl in the presence of water to give monoallylated keto-ols (2a, 2b) and/or diallylated diols (3a, 3b, 3c), this depending upon the employed molar ratio [diketone]/[allyltin chloride]. Bu(CH₂=CHCH₂)SnCl₂ reacts with neat 1c in a one-pot synthesis to give mixtures of heterocyclic compounds: 2,5-diallyl-2,5-dimethyltetrahydrofuran (4), and 3-chloro-1,5-dimethyl-8-oxabicyclo [3,2,1] octane (5). Compound 4 is also obtained in high yield from the corresponding diol 3c by cyclodehydration promoted by RSnCl₃ (R = Me and Bu).     

Synthesis of mono- and binuclear dioxomolybdenum(VI) complexes derived from N(4)-substituted thiosemicarbazones: X-ray crystal structures of [(MoO2L)2], [MoO2Lpy] and [MoO2Lpy]

Four molybdenum(VI) thiosemicarbazonato complexes have been synthesized and characterized. The dinuclear complexes [(MoO₂L¹)₂] (1) and [(MoO₂L²)₂] (3) have been prepared by the reaction of [MoO₂(acac)₂] with 2-hydroxyacetophenone N(4)-cyclohexyl (H₂L¹) and N(4)-phenyl (H₂L²) thiosemicarbazones in alcoholic medium. Mononuclear dioxomolybdenum(VI) complexes of the type [MoO₂L¹py] (2) and [MoO₂L²py] (4) have been prepared by the reaction of 1 or 3 with pyridine (py) in alcoholic medium. In all the complexes, molybdenum is coordinated by two terminal oxo-oxygen atoms, (O_t), oxygen, nitrogen and sulfur atoms from the principal ligand and by an oxygen atom from the second unit in 1, and by a nitrogen atom from pyridine in complexes 2 and 4. All complexes have been spectroscopically characterized. The molecular structures of complexes 1, 2 and 4 have been determined by the single crystal X-ray diffraction method.     

Selenium-capped trimolybdenum and tritungsten carbonyl clusters [Se2M3(CO)10] (M = Mo, W)

A facile synthesis of the novel selenium-capped trimolybdenum and tritungsten ring carbonyl clusters [Se₂M₃(CO)₁₀]²⁻ (M = Mo, 1; W, 4) have been achieved. The selenium-capped trimolybdenum cluster compound [Et₄N]₂[Se₂Mo₃(CO)₁₀] ([Et₄N]₂[1]) can be obtained from the reaction of the trichromium cluster compound [Et₄N]₂[Se₂Cr₃(CO)₁₀] with 4 equiv. of Mo(CO)₆ in refluxing acetone. On the other hand, when [Et₄N]₂[Se₂Cr₃(CO)₁₀] reacted with 4 equiv. of W(CO)₆ in refluxing acetone, the planar cluster compound [Et₄N]₂[Se₂W₄(CO)₁₈] ([Et₄N]₂[3]) was isolated, which could further transform to the tritungsten cluster compound [Et₄N]₂[Se₂W₃(CO)₁₀] ([Et₄N]₂[4]) in good yield. Alternatively, clusters 1 and 4 could be formed from the reactions of the monosubstituted products [Et₄N]₂[Se₂Cr₂M(CO)₁₀] (M = Mo; W, [Et₄N]₂[2]) with 3 equiv. of M(CO)₆ in acetone, respectively. Complexes 1-4 are fully characterized by IR, ⁷⁷Se NMR spectroscopy, and single-crystal X-ray analysis. Clusters 1, 2, and 4 are isostructural and each display a trigonal bipyramidal structure with a homometallic M₃ ring (M = Mo, 1; W, 4) or a heterometallic Cr₂W ring that is further capped above and below by μ₃-Se atoms. Further, the intermediate planar complex 3 exhibits a Se₂W₂ square with each Se atom externally coordinated to one W(CO)₅ group. This paper describes a systematic route to a series of selenium-capped trimetallic carbonyl clusters and the formation and the structural features of the resultant clusters are discussed.     

Electrorheological properties and structure of (BaTiO(C2O4)2/NH2CONH2)

The core-shell structural (BaTiO(C₂O₄)₂/NH₂CONH₂) samples of giant electrorheological (ER) activity have been synthesized by a sol-gel method and studied by TEM, X-ray diffraction and IR spectroscopy. From the analysis of the X-ray diffraction, it is found that the component of samples is (BaTiO(C₂O₄)₂/NH₂CONH₂) with a different content of urea. The observations of the TEM morphology show that (BaTiO(C₂O₄)₂/NH₂CONH₂) particles are spheral with a size of around 80 nm and a surface coating with 5-10 nm thickness consisting of urea. The samples show an increasing tend of ER effect as the addition of urea increasing. Moreover, by IR spectroscopy study, it is revealed that some peaks of CO band and C-O band vibrations of BaTiO(C₂O₄)₂ are split into two peaks after urea added. The extent of the splits increase with the increase of urea content, which is resulted by the interaction between the chemical bonds of urea and oxalate of BaTiO(C₂O₄)₂. It is evident that the giant ER activity of the sample has a close relationship with the interfacial polarization between the core and the shell of (BaTiO(C₂O₄)₂/NH₂CONH₂).     

Theoretical Studies on Dehydrogenation Reactions in Mg2(BH4)2(NH2)2 Compounds

Borohydrides have been recently hightlighted as prospective new materials due to their high gravimetric capacities for hydrogen storage. It is, therefore, important to under-stand the underlying dehydrogenation mechanisms for further development of these ma-terials. We present a systematic theoretical investigation on the dehydrogenation mecha-nisms of theMg₂(BH₄)₂(NH₂)₂ compounds. We found that dehydrogenation takes place most likely via the intermolecular process, which is favorable both kinetically and thermo-dynamically in comparison with that of the intramolecular process. The dehydrogenation of Mg₂(BH₄)₂(NH₂)₂ initially takes place via the direct combination of the hydridic H in BH₄^- and the protic H in NH₂^-, followed by the formation of Mg-H and subsequent ionic recombination of Mg-H^δ- …H^δ+N.     

Synthesis and characterization of trans -Mo(CO)4( p -C5NH4SO3Na)2

Reaction between Mo(CO)₆ and p-C₅NH₄SO₃Na (1:2 (Mo: p-C₅NH₄SO₃Na) stoichiometric ratio) gave the trans-Mo(CO)₄(p-C₅NH₄SO₃Na)₂ complex, (1), in 80% yield. Complex (1) has been characterized by FTIR, ¹H and ¹³C NMR spectroscopy. Complex (1) has most likely an idealized D_4h geometry with trans N-bound p-C₅NH₄SO₃Na ligands.