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1.
Yellowish crystals of K2[(UO2)As2O7] ( 1 ) have been synthesized by solid‐state reactions method. The structure of 1 [orthorhombic, Pmmn, a = 12.601(2), b = 13.242(2), c = 5.621(1) Å, V = 937.9(3) Å3, Z = 4] has been solved by direct methods and refined to R1 = 0.049, wR2 = 0.1060 for 1059 observed reflections. The structure of 1 is based upon [(UO2)As2O7]2? sheets formed by corner sharing between [UO6]6? distorted octahedra and [As2O7]4? polyarsenate groups. The K+ cations are either in eightfold or tenfold coordination and are located between the sheets. The topology of the uranyl arsenate sheet is related to silicate minerals of the melilite group and related synthetic silicate, aluminate and germanate compounds. 相似文献
2.
51V quadrupolar central transition NMR spectra of buffered (pH 7.6-8.0) solutions of bovine apo-transferrin (Tf) and bovine prostatic acid phosphatase (Pp) treated with vanadate show normal features (chemical shifts between -515 and -542 ppm) corresponding to the complexation of VO2+ to the Tf binding site and the Pp active centre, respectively. Addition of H2O2 leads to the temporary formation of complexed VO(O2)+ (delta approximately -595). Vanadate-dependent bromoperoxidase from the alga Ascophyllum nodosum exhibits an unusually high shielding both for the native (delta = -931) and the peroxo form (delta = -1135) of the enzyme. A resonance at -471 ppm is traced back to an inactive form with oxovanadium(V) in a trigonal-bipyramidal array. 相似文献
3.
η5-C5H5V(NO)2CO is prepared in 40% yield by the photo-reaction between η5-C5H5V(CO)4 and [Co(NO)2Br]2.η5-C5H5V(NO)2CO reacts by an SN1 mechanism with various phosphines PZ3 to yield η5-C5-H5V(NO)2PZ3. The phosphine complexes are also obtained by photo-induced ligand interchange between η5-C5H5V(CO)3PZ3 and [Co(NO)2Br]2, or η5-C5H5V(CO)4 and Co(NO)2Br(PZ3). In all cases, the main cobalt species formed is Co(NO)(CO)3. While the one-bond vanadiumphosphorus coupling constants of most of the phosphine complexes are virtually the same (ca 410 Hz),the chemical shift values δ(51V) (?1328 to ?973 ppm rel. VOCl3) decrease in the order PF3 > CO > P(OR)3 > P(alkyl)3 > PPh3 > PPh(NEt2)2, reflecting the decreasing π-acceptor ability of the ligands. δ(51V) also decreases in the series of alkylphosphines PR3 (R = Me, Et, Prn, Bui, Pri, BUt) as the cone angle of PR3increases. 相似文献
4.
A. Müller E. Krickemeyer F. El-Katri D. Rehder A. Stammler H. Bgge F. Hellweg 《无机化学与普通化学杂志》1995,621(7):1160-1170
Simple Trithio- and Perthiocarbonato Complexes with Interesting Bond Properties: [E(CS3)2]2? (E = Sn, Zn, Cd), [E(CS3)3]3? (E = As, Sb, Bi, Co), {Cu(CS3)?}∞ and [Zn(CS4)2]2? By reactions of potassium trithiocarbonate ( 1 ) with solutions of zinc(II)- acetylacetonate, cadmium(II)-chloride, tin(II)-chloride, arsenic(III)-sulfide (suspension), antimony(III)-chloride, bismuth(III)-chloride and copper(II)-chloride in dimethyl sulfoxide, as well as of trisodium hexanitrito cobaltate(III) in water, and the precipitation of the complexes with an aqueous solution of tetraphenylphosphonium chloride the compounds (PPh4)2[Zn(CS3)2] ( 2 ), (PPh4)2[Cd(CS3)2] ( 3 ), (PPh4)2[Sn(CS3)2] ( 4 ), (PPh4)3[As(CS3)3] ( 5 ), (PPh4)3[Sb(CS3)3] ( 6 ), (PPh4)3[Bi(CS3)3] ( 7 ), (PPh4)3[Co(CS3)3] ( 8 ) and (PPh4)Cu(CS3) ( 9 ) have been isolated. (PPh4)2[Zn(CS4)2] · CH3NO2 ( 10 ) has been prepared by heating a solution of 2 in nitromethane to 60--70°C in presence of air. The reaction of 1 in dimethyl sulfoxide with an aqueous tetraphenylphosphonium chloride solution in presence of oxygen leads to (PPh4)2[C2S6] ( 11 ). The compounds have been characterized by spectroscopical studies (IR, Raman, UV/Vis, 113Cd/59Co-NMR), magnetic susceptibility measurements, powder diffractometry, elemental analyses and single crystal X-ray structure analysis ( 4 – 7 , 10 and 11 ). The difficult growing of single crystals has been reported in detail. For crystal data see Inhaltsübersicht. 相似文献
5.
Topological properties of clusters are used to extract critical parameters. This method is tested for the bulk properties ofd=2 percolation and thed=2, 3 Ising model. For the latter we obtain an accurate value of the critical temperatureJ/k
B
T
c=0.221617(18). In the case of thed=3 Ising model with film geometry the critical value of the surface coupling at the special transitions is determined as J1c/J=1.5004(20) together with the critical exponents
1
m
=0.237(5) and=0.461(15). 相似文献
6.
7.
Omar Deeb Prof. Monika Leibscher Dr. Jörn Manz Prof. Wulf von Muellern Tamar Seideman Prof. 《Chemphyschem》2007,8(2):322-328
We propose an approach for separating nuclear spin isomers with coherent light and illustrate it by numerical calculations using fulvene as a model system. The scheme employs the equivalence of torsion and interchange of equivalent H-atoms in a class of molecules of which fulvene is a simple example. The exchange symmetry couples with the rotational symmetry to produce a spatial distinction between the two photo-excited nuclear spin isomers, and wavepacket interferometry is applied to separate the species. 相似文献
8.
Renate Borowski Dieter Rehder Klaus von Deuten 《Journal of organometallic chemistry》1981,220(1):45-54
Photo-reaction between the ligands Ph2ECH2EPh2 (E = P: dppm, E = As: dpam, E = Sb: dpsm), L, and the vanadium complexes η5-C5H5V(CO)4 and [Et4N][V(CO)6] yields monosubstituted mononuclear (dpsm) and dinuclear, ligand-bridged complexes (dpam, dpsm). With dppm, the final products are disubstituted chelate complexes, but monosubstituted mono- and dinuclear species are formed as intermediates.The shielding of the 51V nucleus decreases in the series dpsm > dppm > dpam and {M(CO)n} > {M(CO)n?1} L > {M(CO)n?1}2μ-L > {M(CO)n?2}dppm ({M(CO)n}[V(CO)6]?, η5-C5H5V(CO)4). The half-widths of the NMR signals are greater for dinuclear than for mononuclear complexes.The crystal and molecular structures of η5-C5H5V(CO)3As2Ph4 have been determined. The compound crystallizes in the space group P21/c with a = 1347.8, b = 1020.0, c = 2085.2 pm and β = 82.3°. Due to steric crowding, the 51V shielding is low composed to that of {η5-C5H5V(CO)3}2μ-dpam. 相似文献
9.
Thapper A Behrens A Fryxelius J Johansson MH Prestopino F Czaun M Rehder D Nordlander E 《Dalton transactions (Cambridge, England : 2003)》2005,(21):3566-3571
Reaction of the tetradentate ligand N-(2-hydroxybenzyl)-N,N-bis(2-pyridylmethyl)amine (L-OH) with MoO2Cl2 in methanol in the presence of NaOMe and PF6- results in the formation of [MoO2(L-O)]PF6. Similarly, the reaction of N-(2-mercaptobenzyl)-N,N-bis(2-pyridylmethyl)amine (L-SH) with MoO2(acac)2 leads to the formation of [MoO2(L-S)]+. The dioxo-molybdenum complex [MoO2(L-O)]+ reacts with phosphines in methanol to afford phosphine oxides and an air-sensitive molybdenum complex, tentatively identified as [Mo(IV)O(L-O)(OCH3)]. The latter complex is capable of reducing biological oxygen donors such as DMSO or nitrate, thereby mimicking the activity of DMSO reductase and nitrate reductase. Reaction of [MoO2(L-O)]PF6 with PPh3 in other solvents than methanol leads to the formation of the Mo(V) dimer [(L-O)OMo(micro-O)MoO(L-O)](PF6)2. The crystal structures of [MoO2(L-O)]PF6 and the micro-oxo bridged dimer are presented. 相似文献
10.
We used a combination of theoretical and experimental methods to derive the spectroscopic properties of imidazolium-based ionic liquids. Vibrational frequencies, NMR chemical shifts, and quadrupole coupling constants react in comparable manner to changes in the chemical environment. This suggests that both the IR and the NMR spectroscopic properties reflect a similar type of electronic perturbation caused by hydrogen bonding. These relationships of the spectroscopic properties provide detailed information about structural complexes and may thus serve as good indicators of ion-pair formation. They also help to decide which spectroscopic tool is the most sensitive for investigating molecular interactions. The measurement of only one spectroscopic property allows the prediction of other properties that cannot be so easily measured. In some cases, this is the only way to obtain reliable coupling constants for deriving molecular correlation times from macroscopic NMR relaxation times, thus opening a new path for studying structure-dynamics relations in ionic liquids. 相似文献