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31.
[Re(CO)6][BF4] reacts with HMPA to form [Re(CO)3(HMPA)3][BF4] (4), whose structure was determined by X-ray crystallography and proves to be a key intermediate in the ligand exchange reaction between three CO and Cp; and may be related to other cations such as [Re(CO)3(H2O)3]+, [Re(CO)3(CH3CN)3]+, [Re(CO)3(DMSO)3]+, obtained by different ways, and important in the field of organometallic radiopharmaceuticals. 相似文献
32.
WANG Xiu-li BI Yan-feng LIN Hong-yan LIU Guo-cheng 《高等学校化学研究》2007,23(3):50-253
Hydrothermal treatment of MCl2(M=Co or Cu), NH4VO3, and 1,10-phenanthroline-5,6-dione(pdon) resulted in the formation of a duplex coordination polymer [Co(bpdc)(H2O)3]·H2O(bpdc=2,2′-bipyridine-3,3′-dicarboxylate) and a chain-like coordination polymer [Cu(bpy)V2O6](bpy=2,2′-bipyridine). X-ray single-crystal structural analysis shows that under hydrothermal conditions and in the presence of different transition metals, the organic reagent pdon was transformed in situ into bpdc and bpy, respectively. Mechanism of the in situ ligand synthesis reaction has been discussed. 相似文献
33.
The role of achiral sorbent matrix in chiral recognition of amino acid enantiomers in ligand-exchange chromatography 总被引:2,自引:0,他引:2
Summary As an alternative to the known three-point interaction model describing recognition of optical isomers by a chiral resolving agent, a new concept has been developed stating that two interaction points between the resolving agent and the enantiomers are also sufficient for achieving chiral recognition of the latter, provided that the diastereomeric adducts formed by the resolving agent with the enantiomers additionally interact with a non-chiral chromatographic sorbent. This concept is based on the results of ligand-exchange chromatography of -amino acid enantiomers with copper(II) complexes of chiral bifunctional ligands as the resolving agents in chromatographic systems. 相似文献
34.
Villareal V Kaddis J Azad M Zurita C Silva I Hernandez L Rudolph M Moran J Gomez FA 《Analytical and bioanalytical chemistry》2003,376(6):822-831
Partial-filling affinity capillary electrophoresis (PFACE) is used to examine the binding interactions between two model biological systems: D-Ala-D-Ala terminus peptides to the glycopeptide antibiotic vancomycin (Van) from Streptomyces orientalis, and arylsulfonamides to carbonic anhydrase B (CAB, EC 4.2.1.1, bovine erythrocytes). Using these two systems, modifications in the PFACE technique are demonstrated including flow-through PFACE (FTPFACE), competitive flow-through PFACE (CFTPFACE), on-column ligand synthesis PFACE (OCLSPFACE), and multiple-step ligand injection PFACE (MSLIPFACE). In PFACE small plugs of sample are injected into the capillary column and an equilibrium is established between receptor and ligand during electrophoresis. Binding constants are then obtained by Scatchard analysis using changes in the migration time of the receptor/ligand on changing the concentration of the ligand/receptor. Data demonstrating the quantitative potential of these methods are presented. This review focuses on the unique capabilities of the different PFACE techniques as applied to two model biological systems. 相似文献
35.
Bruce R. McGarvey 《Coordination chemistry reviews》1998,170(1):75-92
Using a newly proposed approach involving an internally consistent set of equations, the ligand field parameters Δ/ξ, V/ξ and k are obtained from literature values of the g matrix for strong field d5 systems of various conformations in which |Δ/ξ|≤10. Qualitative analysis of the observed results is done using the Angular Overlap Model, AOM. 相似文献
36.
Raymond K. Sheline Harald Mahnke 《Angewandte Chemie (International ed. in English)》1975,14(5):314-321
It has been proven qualitatively by a number of authors using variable temperature NMR experiments that most metal carbonyl complexes are nonrigid. A quantitative determination of the ligand exchange frequency ve is often achieved by a line shape analysis or by measurement of the transverse relaxation time T2 using the Carr-Purcell method. In the case of a “very fast” exchange, however, both methods prove unsuccessful. It is shown in this study that a simultaneous fit of IR or Raman spectra on the one hand and NMR spectra on the other can make possible the determination of ve for the “very fast” exchange and can also facilitate the determination of ve in “slow” and “medium” exchange cases considerably. The ligand exchange frequency thus found for Fe(CO)5, 1.1 × 1010s?1, is unexpectedly high; comparison with variable temperature measurements on solid Fe(CO)5, yields similar energy barriers. A mechanism of exchange closely related to the “Berry mechanism” is proposed. Finally the consequences of this surprisingly large ligand exchange rate are discussed with respect to IR band assignments for molecular “fragments” M(CO)x (where x=coordination number, and M is a transition metal, typically lanthanoid or actinoid). 相似文献
37.
Thiam Seong Chong 《Journal of organometallic chemistry》2005,690(18):4132-4138
Three methods of obtaining time-resolved Fourier-Transform infrared (TR-FTIR) absorption spectra of transition metal carbonyl radicals in hexane are reported here. For the first method, CpM(CO)2L and Cp*M(CO)2L (M = Mo, W; L = CO, PR3) radicals have been generated by photodissociation of the corresponding metal-metal bonded dimers. Radicals of formula M(CO)4L (M = Mn, Re; L = CO, PR3, AsPh3, SbPh3) and CpM(CO)n (M = Fe, Mo; n = 2, 3) have been produced via the second method which is halogen abstraction of the transition metal carbonyl halides using CpMo(CO)3 radical. For the third method, fast radical ligand substitution kinetics has been exploited to generate CpMo(CO)2PR3 radicals from CpMo(CO)3 in the presence of free phosphines. An assessment of the three methods with respect to TR-FTIR spectroscopic detection of radicals was also discussed. 相似文献
38.
Treatment of the ligand 6‐aza‐2‐thiothymine (ATT, HL, 1 ) with palladium chloride in methanol forms the ionic complex [(HL)4Pd]Cl2·8MeOH ( 2 ), while its reaction with palladium iodide in same solvent produces the neutral complex trans‐[(HL)2PdI2]·2MeOH ( 3 ) in high yields. The reaction of 1 with Na2[PdCl4] in the presence of sodium acetate in a molar ratio of 2:1:2 and with platinum(II) chloride in presence of sodium acetate led to the dimer tetranuclear complexes [(L4Pd2)NaCl]2·8MeOH ( 4 ) and [L4Pt2Cl2]·6MeOH·H2O ( 5 ). The latter is the first PtIII complex of the ligand. All complexes were characterized by elemental analyses and IR spectroscopy and the crystal structures of 2 , 3 , 4 and 5 are determined by single‐crystal X‐ray diffraction. Crystal data for 2 at ?80 °C: triclinic space group , a = 1006.6(1), b = 1006.9(1), c = 1158.1(1) pm, α = 85.20(1)°, β = 83.84(1)°, γ = 88.91(1)°, Z = 1, R1 = 0.0278; for 3 at ?80 °C: triclinic space group , a = 490.5(1), b = 977.2(2), c = 1116.8(2) pm, α = 90.26(1)°, β = 102.33(1)°, γ = 96.08(1)°, Z = 1, R1 = 0.0394; for 4 at ?80 °C: orthorhombic space group Ccca, a = 1791.7(2), b = 1874.1(2), c = 2044.0(1) pm, Z = 4, R1 = 0.0341 and for 5 at ?80 °C: monoclinic space group P21/c, a = 1464.3(1), b = 2003.7(1), c = 1368.5(1) pm, β = 95.66(1)°, Z = 4, R1 = 0.0429. 相似文献
39.
Two ligand exchange chiral stationary phases (CSPs) based on (S)-leucinol derivative, sodium N-((S)-1-hydroxymethyl-3-methylbutyl)-N-undecylaminoacetate, and (R)-phenylglycinol derivative, sodium N-((R)-2-hydroxy-1-phenylethyl)-N-undecylaminoacetate, covalently bonded to silica gel have been successfully applied in the resolution of nine -hydroxycarboxylic acids. The latter was more effective than the former, the separation factors () being 1.05 to 2.12 while the resolution factors (RS) varying from 0.18 to 5.29 on the latter. The chromatographic resolution behaviors were dependent on the type and the content of organic modifier and the content of CuSO4 in aqueous mobile phase and the column temperature. A possible chiral recognition mechanism was also proposed based on the chromatographic resolution behaviors. 相似文献
40.
The 60 even permutations of the ligands in the five-coordinate complexes, ML
5, form the alternating group A
5, which is isomorphic with the icosahedral pure rotation group I. Using this idea, it is shown how a regular icosahedron can be used as a topological representation for isomerizations of the five-coordinate complexes, ML
5, involving only even permutations if the five ligands L correspond either to the five nested octahedra with vertices located at the midpoints of the 30 edges of the icosahedron or to the five regular tetrahedra with vertices located at the midpoints of the 20 faces of the icosahedron. However, the 120 total permutations of the ligands in five-coordinate complexes ML
5 cannot be analogously represented by operations in the full icosahedral point group I
h, since I
his the direct product I×C2 whereas the symmetric group S
5 is only the semi-direct product A
5S2. In connection with previously used topological representations on isomerism in five-coordinate complexes, it is noted that the automorphism groups of the Petersen graph and the Desargues-Levi graph are isomorphic to the symmetric group S
5 and to the direct product S
5×S
2, respectively. Applications to various fields of chemistry are briefly outlined. 相似文献