从配位聚合物到单分子化合物的转化：Demko-Sharpless四唑合成法制备两个新颖的Co(II)配合物

The reaction of CoCl₂·6H₂O with 4-cyanopyridine N-oxide in the present of NaN₃ affords two novel complexes, {[(POTZ)(H₂O)₂N₃]Co(H₂O)} (1) and Co(POTZ)₂(H₂O)₄ (2) (POTZ=4-tetrazolyl pyridine N-oxide), which are two different phases yielded at different stages of a single Demko-Sharpless′ tetrazole synthesis reaction. Surprisingly the 1D chain coordination polymer 1 is almost completely converted into monomeric complex 2 in this reaction, and, in a separate test, 2 also can be converted into 1. CCDC: 641222, 1; 641223, 2.     

三种1,10-邻菲咯啉-铜(Ⅱ)-L-氨基酸配合物与DNA的相互作用

The Interaction of three complexes [Cu(phen)(Gly)(H₂O)]·ClO₄·2.5H₂O (1), [Cu(phen)(L-Val)(H₂O)]·ClO₄ (2) and [Cu(phen)(L-Ile)(H₂O)]·ClO₄ (3) (phen=1,10-phenanthroline, Gly=glycinate, L-Val=L-valinate, L-Ile=L-isoleucinate) with DNA have been investigated by electronic absorption spectroscopy, ethidium bromide(EB) fluorescence spectroscopy, viscosity and gel electrophoresis measurements. The intensity of maximal absorption peaks from absorption spectra are weakened with dropping DNA into the complexes. The emission intensity of EB-DNA systems in fluorescence spectroscopy have descended 50%, when the data of C_Cu / C_DNA is 30～40. Moreover, the viscosity of DNA increase and then decrease with the increasing of complexes. All of the results indicate that the interaction of complexes with DNA are partial intercalation, and the result of agarose gel electrophoresis show that the complexes can cleave pBR322 DNA in the present of H₂O₂ / vitamin C.     

手性双核Salen配合物的合成与谱学性质

Six novel chiral dinuclear Salen complexes [Cu₂L₁·H₂O (3a), Cu₂L₂(3b), Ni₂L₁·2H₂O (4a), Ni₂L₂(4b), Mn₂Cl₂L₁·H₂O (5a), Mn₂Cl₂L₂ (5b)] have been synthesized(L₁ and L₂ are chiral dimeric Salen ligands with different chain length which were synthesized from (R,R)-diaminocyclohexane, salicylaldehyde, 4,4′-(1,10-decaneoxy)salicylaldehyde, 4,4′-(1,6-hexyloxy)salicylaldehyde). These compounds were charactered by elemental analysis, ¹H NMR, FT-IR, UV-Vis and CD spectra. The FT-IR, UV-Vis and CD spectra were discussed and compared with those of monomeric ligand and complex in detail. It was found that the spectra properties of compounds of different chain length were almost alike, and the properties of dimeric and monomeric compound were similar too. Furthermore Cotton effect and Cotton split of CD spectra of these chiral compounds were explained by the exciton interaction theory. It seemed that the direction of Cotton split depend on the configuration of diaminohexane. (R,R)-diaminohexane determine the chirality of Salen compounds as negative, and the positive and negative component of Cotton split lie at higher and lower energy respectively.     

一种新的三维超分子化合物[Ni(H2O)6(fum)]·2(hmt)·4H2O的合成和晶体结构(fum=反丁烯二酸根；hmt=六次甲基四胺)

The synthesis of nickel supramolecular compound with hexamethylenetetramine and fumarate ligands is reported. The compound [Ni(H₂O)₆(fum)]·2(hmt)·4H₂O (1) (fum=fumarate; hmt=hexamethylenetetramine) were characterized by elemental analysis, crystal structure, IR. Compound 1 crystallizes in the triclinic system, space group P1, and with Z=1. Cell parameters: a=0. 934 6(1), b=0.933 8(1), c=0.938 8(2) nm, α=79.46(1)°, β=77.84(1)°, γ=61.29 6(7)°. Every metal ion has a octahedral coordination geometry formed by six oxygen atoms from six water molecules, and the relative independent components [Ni(H₂O)₆]²⁺, fumarate anions, hmt and H₂O molecules are linked together by two kinds of hydrogen bonds (O-H…O, and O-H…N) to form a three-dimensional structure. CCDC: 256355.     

含有双螺旋链的配位聚合物[Co(dpa)prz0.5]n的合成、晶体结构及磁性质

A coordination polymer [Co(dpa)prz_0.5]_n(1) with double-helix chains has been constructed hydrothermally using H₂dpa (H₂dpa=diphenic acid), prz (prz=piperazine) and Co(NO₃)₂·6H₂O. The structure and magnetic properties of the complex were investigated. The complex crystallizes in triclinic system and P1 space group. Each Co atom is five-coordinated and takes a distorted tetragonal pyramid geometry. Two carboxylates of the H₂dpa ligands bridge four Co(Ⅱ) ions to form infinite right-handed or left-handed helical -C-O-Co- chains. The two types of helical chains are interconnected to each other through the Co(Ⅱ) centers to produce double-helix chains. The chains form a 2D sheet through the coordination interaction of prz molecules between adjacent chains. The sheets are further interlinked by hydrogen bond interactions to generate 3D coordination frameworks. Magnetic studies for complex 1 show stronger antiferromagnetic coupling between the Co(Ⅱ) ions. CCDC: 709275.     

银(Ⅰ)、锌(Ⅱ)与2，2′-(2-氨基-苯氧基)乙醚配合物的合成及晶体结构

The compound 2,2′-(2-amino-phenoxy)-ether[L] was synthesized from the reaction of diethylene glycol with tosyl chloride. AgClO₄ and ZnCl₂ each react with L to give two complexes [Ag₂L₂(H₂O)(ClO₄)₂] (1) and [ZnLCl₂]_n (2) respectively, and characterized by FTIR and single crystal X-ray diffraction. The results of structural analysis indicated that both complexes crystallize in the monoclinic system with space group P2₁/c. 1 is a dinuclear complex, and 2 forming 1D zigzag chain by Zn(Ⅱ) linking adjacent ligands in turn. When viewed from the top of the chain, the structure of 2 shows the unidimensional tube. CCDC: 748592, 1; 748594, 2.     

配位聚合物{[CoL][FeⅡFeⅢ(ox)3·1.5H2O]}∞的合成、波谱表征和磁学性质

A new Schiff base complex， CoL(ClO₄)·3H₂O (1) {L represents condensed from equal molar ratio of sali-cylaldehyde and diethylenetriamine} was synthesized and characterized. Further， a new coordination polymer， {[CoL][Fe^ⅡFe^Ⅲ(ox)₃·1.5H₂O]}_∞ (2)， was synthesized and characterized， where ox^2-=oxalate. The results of the IR and M?ssbauer spectra of 2 revealed that the coordination polymer exists 2-D layer structure in the solid state， and anions layer was formed by [^ⅡFe^Ⅲ(ox)₃]^- unit. The magnetic properties of 2 have been measured and the results indicate that there is magnetic ordering in the low temperature， which may arise from intermolecular ferromagnetic interactions or spin canted effects.     

Reaction of 2-methyl-3-morpholino-1-phenylprop-2-en-1-one with Ru3(CO)12

The reaction of Ru₃(CO)₁₂ with 2-methyl-3-morpholino-1-phenylprop-2-en-1-one (1) produced the Ru₆(CO)₁₆(μ₄-η¹:η¹:η²:η²-PhC(O)-C(Me)=C)₂ (2), Ru₂O₂(CO)₄(η³-OC(Ph)C(Me)C(H)C(Me)₂C(Ph))₂ (3), and [Ru(CO)₂(PhCO₂)(O(CH₂-CH₂)₂NH]₂ (4) complexes, which were characterized by IR and NMR spectroscopy. The structures of the complexes were established by X-ray diffraction. The formation of the complexes is accompanied by deamination of ligand 1. Complexes 2 and 3 bearing the vinyl ketone groups contain five-membered oxaruthenacycles and dihydropyran rings. Morpholine is not removed from the reaction mixture and leads to the formation of complex 4. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2063–2068, December, 2006.     

Schiff碱双核Mn配合物的合成、结构和性能研究

Five manganese complexes of Schiff base were synthesized： [Mn^Ⅳ，Ⅳ(μ-O)(Salen)]₂·DMF·H₂O (1)， [Mn^Ⅳ，Ⅳ(μ-O)(5-BrSalen)]₂·DMF·0.5H₂O (2)， {Mn^Ⅳ，Ⅳ(μ-O)[Sal(1，2-pn)]}₂·H₂O (3)， {Mn^Ⅳ，Ⅳ(μ-O)[5-Br-Sal(1，2-pn)]}₂·H₂O (4)， {Mn^Ⅳ，Ⅳ(μ-O)[5-CH₃-Sal(1，2-pn)]}₂·2H₂O (5)， and were characterized by element analysis， IR and UV-Vis spectra. The results of cyclic voltammogram show that Schiff base ligands can drop the potential of manganese and steady high oxide state of manganese. The magnetic properties of 1 and 3 have also been studied. The results show that there is a weak ferromagnetically coupling of Mn^Ⅳ₂ pair at room and low temperature， and the interactions of complex 3 are weaker than complex 1.     

SnCl4催化丙酮与过氧化氢反应制取大环过氧化物

SnCl₄^.5H₂O and SnCl₂^.2H₂O are the efficient catalysts for the oxidation of acetone with 30% hydrogen peroxide at room temperature to tetrametric acetone peroxide which is identified by molecular determination，elemental analysis，FT-IR，NMR，and MS．The catalytic activity of SnCl₄^.5H₂O and SnCl₂^.2H₂O is much higher than that of HCl．In the case of SnCl₄^.5H₂O，the maximum yield of tetrametric acetone peroxide reaches 95.0%．The results show that the active species of catalytic reaction may be Sn⁴⁺.     

Simple organofluorine compounds giving field-dependent 13C and 19F NMR spectra with complex patterns: higher order effects and cross-correlated relaxation

The CF(3) signals in the (13)C{(1)H} spectrum of 1,1,1,3,3,3-hexafluoroisopropyl alcohol and the (CF(3))(2) CH signals in the corresponding triflate exhibit much greater complexity than might first be expected. The same holds for the (13)C satellites in the (19)F spectra. Complex patterns appear because of higher order effects resulting from the combination of a relatively large four-bond (19)F-(19)F J coupling in the ((13)CF(3))(12)CH((12)CF(3))-containing isotopomer and a typical large one-bond (13)C/(12)C isotope effect on the (19)F chemical shift. This complexity cannot be eliminated at very high magnetic field strengths. The triflate (CF(3))(2)CH-O-SO(2)CF(3) presents still additional complexity because of the presence of two different types of CF(3) groups exhibiting (6)J(FF) in any of the isotopomers and the chemical shift differences in hertz between the various (19)F signals in the two different (13)CF(3)-containing isotopomers. In addition, the presence of a small (5)J(CF) in the ((13)CF(3))((12)CF(3))(12)CH-O-SO(2) (12)CF(3) isotopomer is revealed only through simulations. The hexafluoroisopropyl CF(3) groups in the alcohol and triflate and the SO(2)CF(3) group in the triflate apparently provide the first examples of cross-correlated relaxation in (13)CF(3) groups. An analysis of the spectra in the context of previously reported work highlights the novel aspects of our findings. In particular, for each part of the complex hexafluoroisopropyl CF(3) quartet, peak height and linewidth variations resulting from cross-correlated relaxation are observed. These variations within a group of (13)C signals reflect different spin-lattice and spin-spin relaxation rates for the transitions within that group arising from higher order coupling effects.     

New developments and directions in the area of elastomers and rubberlike elasticity

There are number of important developments in the area of elastomeric polymers, including (i) network chains of controlled stiffness, (ii) model elastomers (including dangling-chain networks), (iii) fluorosiloxane elastomers, (iv) new thermoplastic elastomers, (v) other new elastomers, (v) bimodal network chain-length distributions, (vi) cross linking in solution or in a state of deformation, and (vii) gel collapse. Interesting elastomeric composites include those with (i) in-situ generated ceramic-like particles, (ii) ellipsoidal fillers, (iii) clay-like layered fillers, (iv) polyhedral oligomeric silsesquioxane (POSS) particles, (v) porous fillers, (vi) elastomeric domains modifying ceramics, and (vii) controlled interfaces. New characterization techniques are being developed for elastomers, and there have been new developments in elasticity theory and in elastomer processing. Some examples of societal aspects of relevance are (i) synthesis of elastomers in environmentally-friendly solvents, (ii) biosynthesis, (iii), recyclability, (iv) improved adhesion to tire cords, and (v) better barrier properties in anti-terrorism clothing. Educational topics include curriculum development, and mobile laboratories for elastomer experiments and demonstrations.     

N,N'-ethylenebis(pyridoxylideneiminato) and N,N'-ethylenebis(pyridoxylaminato): synthesis, characterization, potentiometric, spectroscopic, and DFT studies of their vanadium(IV) and vanadium(V) complexes

The Schiff base N,N'-ethylenebis(pyridoxylideneiminato) (H(2)pyr(2)en, 1) was synthesized by reaction of pyridoxal with ethylenediamine; reduction of H(2)pyr(2)en with NaBH(4) yielded the reduced Schiff base N,N'-ethylenebis(pyridoxylaminato) (H(2)Rpyr(2)en, 2); their crystal structures were determined by X-ray diffraction. The totally protonated forms of 1 and 2 correspond to H(6)L(4+), and all protonation constants were determined by pH-potentiometric and (1)H NMR titrations. Several vanadium(IV) and vanadium(V) complexes of these and other related ligands were prepared and characterized in solution and in the solid state. The X-ray crystal structure of [V(V)O(2)(HRpyr(2)en)] shows the metal in a distorted octahedral geometry, with the ligand coordinated through the N-amine and O-phenolato moieties, with one of the pyridine-N atoms protonated. Crystals of [(V(V)O(2))(2)(pyren)(2)].2 H(2)O were obtained from solutions containing H(2)pyr(2)en and oxovanadium(IV), where Hpyren is the "half" Schiff base of pyridoxal and ethylenediamine. The complexation of V(IV)O(2+) and V(V)O(2) (+) with H(2)pyr(2)en, H(2)Rpyr(2)en and pyridoxamine in aqueous solution were studied by pH-potentiometry, UV/Vis absorption spectrophotometry, as well as by EPR spectroscopy for the V(IV)O systems and (1)H and (51)V NMR spectroscopy for the V(V)O(2) systems. Very significant differences in the metal-binding abilities of the ligands were found. Both 1 and 2 act as tetradentate ligands. H(2)Rpyr(2)en is stable to hydrolysis and several isomers form in solution, namely cis-trans type complexes with V(IV)O, and alpha-cis- and beta-cis-type complexes with V(V)O(2). The pyridinium-N atoms of the pyridoxal rings do not take part in the coordination but are involved in acid-base reactions that affect the number, type, and relative amount of the isomers of the V(IV)O-H(2)Rpyr(2)en and V(V)O(2)-H(2)Rpyr(2)en complexes present in solution. DFT calculations were carried out and support the formation and identification of the isomers detected by EPR or NMR spectroscopy, and the strong equatorial and axial binding of the O-phenolato in V(IV)O and V(V)O(2) complexes. Moreover, the DFT calculations done for the [V(IV)O(H(2)Rpyr(2)en)] system indicate that for almost all complexes the presence of a sixth equatorial or axial H(2)O ligand leads to much more stable compounds.     

A feasibility study on the use of Li(4)V(3)O(8) as a high capacity cathode material for lithium-ion batteries

Li(4)V(3)O(8) materials have been prepared by chemical lithiation by Li(2)S of spherical Li(1.1)V(3)O(8) precursor materials obtained by a spray-drying technique. The over-lithiated vanadates were characterised physically by using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and electrochemically using galvanostatic charge-discharge and cyclic voltammetry measurements in both the half-cell (vs. Li metal) and full-cell (vs. graphite) systems. The Li(4)V(3)O(8) materials are stable in air for up to 5 h, with almost no capacity drop for the samples stored under air. However, prolonged exposure to air will severely change the composition of the Li(4)V(3)O(8) materials, resulting in both Li(1.1)V(3)O(8) and Li(2)CO(3). The electrochemical performance of these over-lithiated vanadates was found to be very sensitive to the conductive additive (carbon black) content in the cathode. When sufficient carbon black is added, the Li(4)V(3)O(8) cathode exhibits good cycling behaviour and excellent rate capabilities, matching those of the Li(1.1)V(3)O(8) precursor material, that is, retaining an average charge capacity of 205 mAh g(-1) at 2800 mA g(-1) (8C rate; 1C rate means full charge or discharge of a battery in one hour), when cycled in the potential range of 2.0-4.0 V versus Li metal. When applied in a non-optimised full cell system (vs. graphite), the Li(4)V(3)O(8) cathode showed promising cycling behaviour, retaining a charge capacity (Li(+) extraction) above 130 mAh g(-1) beyond 50 cycles, when cycled in the voltage range of 1.6-4.0 V, at a specific current of 117 mA g(-1) (C/3 rate).     

苯甲醛在离子液体中的电化学行为

应用线性扫描循环伏安法、方波循环伏安法和计时电量法测定苯甲醛在3种离子液体C4M IMBF4、C6M IMBF4和C8M IMBF4中的电化学行为.实验表明,在C4M IIVIBF4离子液体中苯甲醛于GC电极上的还原包含两个连续、不可逆单电子过程,对应的方波I~E曲线峰电位Ep为-1.39 V和-1.69 V,估算的扩散系数分别为D1=1.5×10-8cm2/s和D2=1.3×10-8cm2/s.而在C6M IMBF4和C8M IMBF4离子液体中,则苯甲醛于GC电极仅显示一个电流峰,这可能是因为C4M IMBF4的碱性较C6M IMBF4和C8M IMBF4弱的缘故;而电流的衰减时间亦依C4M IMBF4,C6M IMBF4,C8M IMBF4,次序增长,并会导致更慢的异相动力学过程.     

Synthesis of phthalide derivatives using nickel-catalyzed cyclization of o-haloesters with aldehydes

The reaction of o-bromobenzoate (1 b) with benzaldehyde (2 a) in the presence of [NiBr(2)(dppe)] (dppe=1,2-bis(diphenylphosphino)ethane) and zinc powder in THF (24 hours, reflux temperature), afforded 3-phenyl-3H-isobenzofuran-1-one (3 a) in an 86 % yield. Similarly, o-iodobenzoate reacts with 2 a to give 3 a, but in a lower yield (50 %). A series of substituted aromatic and aliphatic aldehydes (2 b, 4-MeC(6)H(4)CHO; 2 c, 4-MeOC(6)H(4)CHO; 2 d, 3-MeOC(6)H(4)CHO; 2 e, 2-MeOC(6)H(4)CHO; 2 f, 4-CNC(6)H(4)CHO; 2 g, 4-(Me)(3)CC(6)H(4)CHO; 2 h, 4-C(6)H(5)C(6)H(4)CHO; 2 i, 4-ClC(6)H(4)CHO; 2 j, 4-CF(3)C(6)H(4)CHO; 2 k, CH(3)(CH(2))(5)CHO; 2 l, CH(3)(CH(2))(2)CHO) also underwent cyclization with o-bromobenzoate (1 b) producing the corresponding phthalide derivatives in moderate to excellent yields and with high chemoselectivity. Like 1 b, methyl 2-bromo-4,5-dimethoxybenzoate (1 c) reacts with tolualdehyde (2 b) to give the corresponding substituted phthalide 3 m in a 71 % yield. The methodology can be further applied to the synthesis of six-membered lactones. The reaction of methyl 2-(2-bromophenyl)acetate (1 d) with benzaldehyde under similar reaction conditions afforded six-membered lactone 3 o in a 68 % yield. A possible catalytic mechanism for this cyclization is also proposed.     

New highly stable metallabenzenes via nucleophilic aromatic substitution reaction

Treatment of the ruthenabenzene [Ru{CHC(PPh(3))CHC(PPh(3))CH}Cl(2)(PPh(3))(2)]Cl (1) with excess 8-hydroxyquinoline in the presence of CH(3)COONa under air atmosphere produced the S(N)Ar product [(C(9) H(6)NO)Ru{CHC(PPh(3))CHC(PPh(3))C}(C(9)H(6)NO)(PPh(3))]Cl(2) (3). Ruthenabenzene 3 could be stable in the solution of weak alkali or weak acid. However, reaction of 3 with NaOH afforded a 7:1 mixture of ruthenabenzenes [(C(9)H(6)NO)Ru{CHC(PPh(3))CHCHC}(C(9)H(6)NO)(PPh(3))]Cl (4) and [(C(9)H(6)NO)Ru{CHCHCHC(PPh(3))C}(C(9)H(6)NO)(PPh(3))]Cl (5), presumably involving a P-C bond cleavage of the metallacycle. Complex 3 was also reactive to HCl, which results in a transformation of 3 to ruthenabenzene [Ru{CHC(PPh(3))CHC(PPh(3))C}Cl(2)(C(9)H(6)NO)(PPh(3))]Cl (6) in high yield. Thermal stability tests showed that ruthenabenzenes 4, 5, and 6 have remarkable thermal stability both in solid state and in solution under air atmosphere. Ruthenabenzenes 4 and 5 were found to be fluorescent in common solvents and have spectral behaviors comparable to those organic multicyclic compounds containing large π-extended systems.     

Ligand cleavage put into reverse: P--C bond breaking and remaking in an alkylphosphane iron complex

Complex formation between FeX(2)6 H(2)O (X=BF(4) or ClO(4)) and the pyridine-derived tetrapodal tetraphosphane C(5)H(3)N[CMe(CH(2)PMe(2))(2)](2) (1) in methanol proceeds with solvent-induced cleavage of one PMe(2) group. Depending on the reaction temperature and the nature of the counterion, iron(II) is coordinated, in distorted square-pyramidal fashion, by the anionic remainder of the chelating ligand, C(5)H(3)N[CMe(CH(2)PMe(2))(2)][CMe(CH(2)PMe(2))(CH(2) (-))] (NP(3)C(-) donor set: X=BF(4), -50 degrees C: 2; X=ClO(4), RT: 4) or its protonated form C(5)H(3)N[CMe(CH(2)PMe(2))(2)][CMe(CH(2)PMe(2))(CH(3))], in which the methyl group is in agostic interaction with the metal centre (X=BF(4), RT: 3; X=ClO(4), +50 degrees C: 5). A monodentate phosphinite ligand Me(2)POMe, formed from the cleaved PMe(2) group and methanol, completes the coordination octahedron in both cases. Working in CD(3)OD (X=BF(4), RT) gives the deuterium-substituted analogue of 3, with ligands L(CH(2)D) (L=residual chelating ligand) and Me(2)POCD(3). A mechanism for the observed phosphorus-carbon bond cleavage is suggested. Complex 2, when isolated at -50 degrees C, is stable in the solid state even at room temperature. The reaction of 2 in methanol with carbon monoxide (10.5 bar) at elevated temperature forms, in addition to as yet unidentified side products, the carbonyl complex [(1)Fe(CO)](BF(4))(2) (7), in which the previous P--C bond cleavage has been reversed, reforming the original tetrapodal pentadentate NP(4) ligand 1. All compounds have been fully characterised, including X-ray structure analyses in most cases.     

Dititanium-containing 19-tungstodiarsenate(III) [Ti2(OH)2As2W19O67(H2O)]8-: synthesis, structure, electrochemistry, and oxidation catalysis

The dititanium-containing 19-tungstodiarsenate(III) [Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)](8-) (1) has been synthesized and characterized by IR, TGA, elemental analysis, electrochemistry, and catalytic studies. Single-crystal X-ray analysis was carried out on Cs(8)[Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)].2CsCl.12H(2)O (Cs-1), which crystallizes in the monoclinic system, space group P2(1)/m, with a=12.7764(19), b=19.425(3), c=18.149(3) A, beta=110.234(3) degrees, and Z=2. Polyanion 1 comprises two (B-alpha-As(III)W(9)O(33)) Keggin moieties linked through an octahedral {WO(5)(H(2)O)} fragment and two unprecedented square-pyramidal {TiO(4)(OH)} groups, leading to a sandwich-type structure with nominal C(2v) symmetry. Synthesis of 1 was accomplished by reaction of TiOSO(4) and K(14)[As(2)W(19)O(67)(H(2)O)] in a 2:1 molar ratio in aqueous, acidic medium (pH 2). Polyanion 1 could also be isolated as a tetra-n-butyl ammonium (TBA) salt, {(n-C(4)H(9))(4)N}(5)H(3)[Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)] (TBA-1). TBA-1 was studied by cyclic voltammetry in acetonitrile (MeCN) solutions containing 0.1 M LiClO(4) and compared with the results obtained with Cs-1 in aqueous media. In MeCN, the Ti(IV) and W(VI) waves could not be separated distinctly. An important adsorption phenomenon on the glassy carbon working electrode was encountered both in cyclic voltammetry and in controlled potential electrolysis and was confirmed by Electrochemical Quartz Crystal Microbalance (EQCM) studies on a carbon film. TBA-1, dissolved in MeCN, reacts with H(2)O(2) to give peroxo complexes stable enough for characterization by UV-visible spectroscopy, cyclic voltammetry, and EQCM. TBA-1 shows high catalytic activity (TOF=11.3 h(-1)) in cyclohexene oxidation with aqueous H(2)O(2) producing products typical of a heterolytic oxidation mechanism. The stability of TBA-1 under turnover conditions was confirmed by using IR, UV-visible spectroscopy as well as cyclic voltammetry.     

Temperature-dependent 11B spin-lattice relaxation time for BF4 and CF3BF3 anions in room-temperature ionic liquids

Temperature-dependent (11)B T(1) values were measured for the BF(4) anion and BF(3) in the CF(3)BF(3) anion in room-temperature ionic liquids (RTILs) composed of the cation N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium (DEME). Including the lithium-salt-doped samples, two neat and two binary ionic liquids were studied. Arrhenius plots of the (11)B T(1) showed T(1) minima for BF(4) in the temperature range between 243 (or above freezing) and 373 K. Using the Bloembergen, Pound, and Purcell(BPP) equations for the (11)B quadrupolar and (11)B-(19) F dipolar relaxation mechanisms, the correlation times for motions of BF(4) were calculated. Since the internal rotation of BF(3) is assumed in CF(3)BF(3), T(1) minimum was not observed. The effects of the addition of the lithium salt on the (11)B correlation time and (11)BT(1) for the anions in the ILs are discussed.