Synthesis and characterization of thermally robust amidinato group 13 hydride complexes

The reactivity of two sterically bulky amidines, ArNC(R)N(H)Ar (Ar=2,6-diisopropylphenyl; R=H (HFiso); tBu, (HPiso)) towards LiMH4, M=Al or Ga, [AlH3(NMe3)], and [GaH3(quin)] (quin=quinuclidine) has been examined. This has given rise to a variety of very thermally stable aluminum and gallium hydride complexes. The structural motif adopted by the prepared complexes has been found to be dependent upon both the amidinate ligand and the metal involved. The 1:1 reaction of HFiso with LiAlH4 yielded dimeric [{AlH3(mu-Fiso)Li(OEt2)}2]. Amidine HFiso reacts in a 1:1 ratio with [AlH3(NMe3)] to give the unusual hydride-bridging dimeric complex, [{AlH2(Fiso)}2], in which the Fiso- ligand is nonchelating. The equivalent reaction with the bulkier amidine, HPiso, yielded a related hydride-bridging complex, [{AlH2(Piso)}2], in which the Piso- ligand is chelating. In contrast, the treatment of [GaH3(quin)] with one equivalent of HFiso afforded the four-coordinate complex [GaH2(quin)(Fiso)], in which the Fiso- ligand acts as a localized monodentate amido-imine ligand. The 2:1 reactions of HFiso with [AlH3(NMe3)] or [GaH3(quin)] gave the monomeric complexes [MH(Fiso)2], which are thermally robust and which exhibit chelating amidinate ligands. In contrast, HPiso did not give 2:1 complexes in its reactions with either of the Group 13 trihydride precursors. For sake of comparison, the reactions of [AlH3(NMe3)] and [GaH3(quin)] with the bulky carbodiimide ArN=C=NAr and the thiourea Ar(H)NC(=S)N(H)Ar were examined. These last reactions afforded the five-coordinate thioureido complexes, [MH{N(Ar)C[N(H)(Ar)]S}2], M=Al or Ga.     

吡啶二甲酸镓、铟配合物的合成及生物活性

吡啶二甲酸能与过渡、非过渡、镧系和锕系金属离子螯合形成稳定的配合物，而且配位方式不拘一格，既可以是双齿，三齿，也可以是桥式配位。吡啶二甲酸的另一重要意义在于它们的生物活性。由于镓具有抗癌，抗肿瘤的活性，吡啶二甲酸镓配合物可能会是一种非常有潜力的新型药物。基于上述事实，本文合成了六种新型的吡啶二甲酸（2，3-，2，5-，2，6-）镓（Ⅲ）、铟（Ⅲ）配合物，并进一步测试了三种镓配合物的生物活性。     

Some novel binuclear group 13 metal tin hydrides formed in Ar matrices following the codeposition of the metal vapor with SnH4

IR measurements show that co-condensation of Al or Ga atoms (M) with SnH4 in a solid Ar matrix at about 12 K results mainly in the spontaneous insertion of the metal into an Sn-H bond to form the M(II) hydride HMSnH3. Simultaneously the Ga2 dimer also reacts with SnH4, possibly to form a nido-type cluster Ga2(mu-H)4Sn, with a metal-deficient cubane-like structure. All of these products are photolabile. Irradiation with visible light causes HMSnH3 to tautomerize to the novel dihydrido-bridged species H3M(mu-H)2Sn, which decomposes in turn under broad-band UV-visible light (lambda=200-800 nm); some H3Al(mu-H)2Sn is formed even on deposition. The data collected from experiments with SnH4 and SnD4 and different reagent concentrations, together with the results of quantum chemical calculations, are used to interpret the results and elucidate the structures and bonding of the new species.     

Developing Lithium Chemistry of 1,2‐Dihydropyridines: From Kinetic Intermediates to Isolable Characterized Compounds

Generally considered kinetic intermediates in addition reactions of alkyllithiums to pyridine, 1‐lithio‐2‐alkyl‐1,2‐dihydropyridines have been rarely isolated or characterized. This study develops their “isolated” chemistry. By a unique stoichiometric (that is, 1:1, alkyllithium/pyridine ratios) synthetic approach using tridentate donors we show it is possible to stabilize and hence crystallize monomeric complexes where alkyl is tert‐butyl. Theoretical calculations probing the donor‐free parent tert‐butyl species reveal 12 energetically similar stereoisomers in two distinct cyclotrimeric (LiN)₃ conformations. NMR spectroscopy studies (including DOSY spectra) and thermal volatility analysis compare new sec‐butyl and iso‐butyl isomers showing the former is a hexane soluble efficient hydrolithiation agent converting benzophenone to lithium diphenylmethoxide. Emphasizing the criticalness of stoichiometry, reaction of nBuLi/Me₆TREN with two equivalents of pyridine results in non‐alkylated 1‐lithio‐1,4‐dihydropyridine?Me₆TREN and 2‐n‐butylpyridine, implying mechanistically the kinetic 1,2‐n‐butyl intermediate hydrolithiates the second pyridine.     

Preparation and thermal decomposition of indium hydroxide

Summary Indium hydroxides were prepared by the mixing of aqueous indium nitrate solution with sodium or ammonium hydroxide solutions under various conditions. The thermal decomposition of the resulting materials was examined by thermogravimetry, differential thermal analysis, X-ray diffraction study and infrared spectroscopy. It has been found that sodium hydroxide solution is more suitable than the addition of ammonium hydroxide solution to prepare indium hydroxide in well crystallization; the thermal decomposition of indium hydroxide, in which the composition is In(OH)₃·xH₂O where x￡2, proceeds according to the following process: In(OH)₃·xH₂O?cubic In(OH)₃?cubic In₂O₃     

Study of the thermal decomposition of cellulose-hyphan and its complexes with some transition and indium metal ions

The studied complexes formed by the chelating ion exchanger were characterized by reflectance and infrared spectrometry. The thermal degradation of pure cellulose-hyphan (CH) and its complexes with Hg²⁺, In³⁺, Cr³⁺, Mo⁴⁺ and Mn²⁺ under an atmosphere of air has been studied using thermal gravimetry (TG) and differential thermal analysis (DTG). The results showed that four different stages are accompanying the decomposition of (CH) and its complexes with the studied metals. These stages were found to be affected by the presence of the investigated metal ions. On the bases of the applicability of a non-isothermal kinetic equation it was found to be a first-order reaction with the rate of degradation,k, ranging from 8.3·10^?5 to 6.2·10^?3 for (CH) and from 1.7·10^?5 to 6.6·10^?3 s^?1 for its complexes. The activation energy,E _a, the entropy change, ΔS°, the enthalpy change, ΔH° and Gibbs free energy, ΔG° are calculated by applying the rate theory of the first-order reaction. The effect of the different central metal ions on the calculated thermodynamic parameters is discussed.     

Nano indium oxide catalyzed efficient synthesis of propargylamines via C-H and C-Cl bond activations

A simple, and efficient nano In₂O₃ catalyzed one-pot three-component coupling of terminal alkyne, dichloromethane, and secondary amine has been developed for the synthesis of propargylamines under mild reaction conditions. The catalyst was recovered and reused for three times without significant loss of catalytic activity.     

Matrix reactivity of Al and Ga atoms (M) in the presence of silane: generation and characterization of the eta2-coordinated complex M.SiH4, the insertion product HMSiH3, and the MI species MSiH3 in a solid argon matrix

Matrix isolation experiments give evidence for the formation of the loosely bonded metal-silane complex M.SiH(4) by the spontaneous reaction of Al or Ga atoms (M) with silane in a solid Ar matrix at 12 K; however, Ga(2) appears to insert spontaneously into an Si--H bond to form HGaGaSiH(3), probably with the structure HGa(micro-SiH(3))Ga. In M.SiH(4) the metal atom is eta(2)-coordinated by the silane, resulting in a species with C(2v) symmetry. The complex has a distinctive photochemistry: it can be converted on photolysis at lambda approximately 410 or approximately 254 nm to its tautomer, HMSiH(3), which also has a doublet ground electronic state and from which it can be regenerated with lambda approximately 580 nm radiation. Broadband UV-visible photolysis (lambda=200-800 nm) results in decomposition of HMSiH(3), the univalent species MSiH(3) being the only detectable product. The experimental data collected for several silane isotopomers (SiH(4), SiD(4), and SiD(3)H) and different reagent concentrations, together with the results of sophisticated quantum chemical calculations, are used to explore in detail the properties of the detected species and the reaction pathways compassing their formation.     

Crystal structure and thermal behavior of a new cadmium indium oxalate

A new mixed metal oxalate Cd₃In₂(C₂O₄)₆·9H₂O, with an open-framework structure, has been prepared from a precipitation method at room temperature. Its crystal structure has been solved from single-crystal diffraction data. The compound crystallizes with space group P6₄22 and the cell parameters are a=8.566(5)Å, c=37.811(5) Å, V=2403(2) Å³, and Z=3 (R₁=0.036). The three-dimensional structure is built from three types of MO₈ (M=Cd, In) polyhedra, i.e., triangular dodecahedra, bicapped trigonal prisms and an undefined distorted eight-fold cadmium polyhedron. Relationships with the structures of the related cadmium zirconium oxalates are discussed. The structure overview suggests the possibility to conceive new oxalate-based materials with open-framework structures. The thermal behavior of the new compound is described in details from temperature-dependent X-ray powder diffraction and thermogravimetry measurements. The dehydration process of the precursor is reversible in its stability temperature range. The final product consists of a mixture of nanocrystalline CdIn₂O₄ and the simple oxides.     

Time-resolved micelle-stabilized room-temperature phosphorimetry for simultaneous determination of gallium and indium

Ga(III) and In(III) react with 7-iodo-hydroxyquinoline-5-sulphonic acid (Ferron) in the presence of CTAB micelles, forming complexes which exhibit analytically useful room-temperature phosphorescence (RTP). The RTP features of the two complexes are similar and the RTP spectra overlap. However, there is sufficient difference between the two phosphorescence decay rates for both metals to be determined by time-resolved room-temperature phosphorimetry.     

Hydrothermal synthesis,characterization and photoluminescence property of a novel indium phosphate with 3D supramolecular structure

A one-dimensional chained indium phosphate In(H₂PO₄)(HPO₄)(C₁₀N₂H₈) (1) was synthesized under hydrothermal condition using 2,2′-bipyridine as a ligand and characterized by IR spectroscopy, ICP and elemental analyses, powder and single crystal X-ray diffraction analyses. Compound 1 crystallizes in the triclinic system, space group P-1. The connection of In-centered octahedra (InO₄N₂) and P-centered tetrahedra ({PO₃(OH)} and {PO₂(OH)₂}) constructs a new type of 1D chained structure with In/P ratio of 1/3. Interestingly, H₂PO₄ tetrahedron and 2,2′-bipyridine ligands "hanging" in the chain by bridging oxygen atoms and nitrogen atoms bond to the central In atoms. It is noted that the adjacent chains are stably packed together and the final structure exhibits interesting three-dimensional (3D) supramolecular array via π–π interactions of the 2,2′-bipyridine groups and hydrogen-bond interactions. Additionally, compound 1 shows strong photoluminescence property in the solid state at room temperature.     

An EPR and ENDOR investigation of a series of diazabutadiene-group 13 complexes

Paramagnetic diazabutadienegallium(II or III) complexes, [(Ar-DAB)2Ga] and [{(Ar-DAB*)GaX}2] (X = Br or I; Ar-DAB = {N(Ar)C(H)}2, Ar = 2,6-diisopropylphenyl), have been prepared by reactions of an anionic gallium N-heterocyclic carbene analogue, [K(tmeda)][:Ga(Ar-DAB)], with either "GaI" or [MoBr2(CO)2(PPh3)2]. A related InIII complex, [(Ar-DAB*)InCl2(thf)], has also been prepared. These compounds were characterised by X-ray crystallography and EPR/ENDOR spectroscopy. The EPR spectra of all metal(III) complexes incorporating the Ar-DAB ligand, [(Ar-DAB(.))MX(2)(thf)(n)] (M = Al, Ga or In; X = Cl or I; n = 0 or 1) and [(Ar-DAB)2Ga], confirmed that the unpaired spin density is primarily ligand centred, with weak hyperfine couplings to Al (a = 2.85 G), Ga (a = 17-25 G) or In (a = 26.1 G) nuclei. Changing the N substituents of the diazabutadiene ligand to tert-butyl groups in the gallium complex, [(tBu-DAB*)GaI2] (tBu-DAB={N(tBu)C(H)}2), changes the unpaired electron spin distribution producing 1H and 14N couplings of 1.4 G and 8.62 G, while the aryl-substituted complex, [(Ar-DAB*)GaI2], produces couplings of about 5.0 G. These variations were also manifested in the gallium couplings, namely aGa approximately 1.4 G for [(tBu-DAB*)GaI2] and aGa approximately 25 G for [(Ar-DAB*)GaI2]. The EPR spectra of the gallium(II) and indium(II) diradical complexes, [{(Ar-DAB*)GaBr}2], [{(Ar-DAB*)GaI}2], [{(tBu-DAB*)GaI}2] and [{(Ar-DAB*)InCl}2], revealed doublet ground states, indicating that the Ga-Ga and In-In bonds prevent dipole-dipole coupling of the two unpaired electrons. The EPR spectrum of the previously reported complex, [(Ar-BIAN*)GaI2] (Ar-BIAN = bis(2,6-diisopropylphenylimino)acenaphthene) is also described. The hyperfine tensors for the imine protons, and the aryl and tert-butyl protons were obtained by ENDOR spectroscopy. In [(Ar-DAB*)GaI2], gallium hyperfine and quadrupolar couplings were detected for the first time.