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81.
Scoles L Sterenberg BT Udachin KA Carty AJ 《Chemical communications (Cambridge, England)》2002,(4):320-321
Reaction of the aminophosphinidene complex [Ru5(CO)15(mu 4-PNPri2)] 1 with [PPN][NO2] (PPN = Ph3P=N=PPh3) led to the mixed nitrosyl/phosphinidene cluster complex [PPN][Ru5(CO)13(mu-NO)(mu 4-PNPri2)] 2 which is transformed into the novel nitrene/phosphinidene cluster [Ru5(CO)10(mu-CO)2(mu 3-CO)(mu 4-NH)(mu 3-PNPri2)] 3 via treatment with triflic acid. 相似文献
82.
Baker MV Barnard PJ Brayshaw SK Hickey JL Skelton BW White AH 《Dalton transactions (Cambridge, England : 2003)》2005,(1):37-43
A series of (pseudo)halo(1,3-di-tert-butylimidazol-2-ylidine)gold complexes [(But2Im)AuX](X = Cl, Br, I, CN, N3, NCO, SCN, SeCN, ONO2, OCOCH3, CH3) have been synthesized and characterised spectroscopically and structurally. 13C NMR chemical shifts for the carbene carbon vary widely with differing ancillary anion, correlating well with the sigma-donor ability of the latter and with the M-C(carbene) bond distance. These results reinforce the notion that N-heterocyclic carbene ligands are primarily sigma-donor ligands with little pi-acceptor ability. 相似文献
83.
Kevin Burgess Brian F.G. Johnson Jack Lewis Paul R. Raithby 《Journal of organometallic chemistry》1982,224(4):C40-C44
Organic azides [N3R] react with [Os3(CO)11(NCMe)] and with [Os3(μ-H)2(CO)10] to form [Os3(CO)10(NCMe)(N3COR)] (R Ph) and [Os3(μ-H)(CO)10(HN3R)] (R Ph, n-Bu, CH2Ph, cyclo-C6H11), respectively; the latter may be converted to [Os3(μ-H)2(CO)9(μ3-NR)] by thermolysis; the molecular structure of the phenyl derivative of each class of compound has been confirmed by x-ray analysis. 相似文献
84.
George R. Clark Brian W. Skelton T.Nell Waters 《Journal of organometallic chemistry》1975,85(3):375-394
The crystal structure of tetrakis(methyldiphenylphosphine)iridium(I) tetrafluoroborate with cyclohexane of solvation, [Ir(PPh2Me)4]BF4·C6H12, has been determined from a three-dimensional X-ray analysis. The compound has been analysed in space group C2/c of the monoclinic system. There are twelve molecules (i.e. 1.5 molecules per asymmetric unit) in a cell of dimensions a = 36.804(8), b = 22.93(2), c = 21.676(4) Å, β = 121.41(1)°. Block-diagonal least-squares refinement has given a final R-factor of 0.060 for 7905 reflections having I > 3σ(I).The structure consists of two crystallographically distinct, but structurally similar molecules, one on a general position and one on a crystallographic two-fold axis. The phosphine ligands around the iridium atoms are in a very distorted square-planar arrangement. The reactions of the cation axe discussed in terms of this structure. 相似文献
85.
Rh(π-C3H5)(PF3)3 (I), reacts with trifluoroacetic acid to form propene and [Rh(CF3COO)(PF3)2]2 (II). I reacts with t-butyl bromide to give [RhBr(PF3)2]2 and a mixture of propene and 2-methyl-1-propene and with n-propyl bromide to give propene and [RhBr(PF3)2]2. Rh(π-C3H5)(PPh3)2 (III), and t-butyl bromide yield propene and 2-methyl-1-propene. In these reactions a mechanism involving β-hydrogen abstraction and hydrogen migration via the metal to carbon is proposed. When III reacts with Me3SnCl the Me3Sn—moiety migrates intact to the π-allyl group. I reacts with acetyl chloride to give propene, [RhCl(PF3)2]2 and the carbonyl rhodium complex Rh2Cl2(PF3)3(CO). II does not apparently undergo phosphine ligand exchange unlike the analogous halogeno-bridged dimers. 相似文献
86.
O-GlcNAcylation of serine and threonine residues is a dynamic and essential post-translational modification involved in signaling pathways in eukaryotes. Studies of O-GlcNAcylation would be aided by small-molecule inhibitors of O-GlcNAc transferase (OGT), the sole enzyme know to mediate this modification, but discovery of such molecules has been hampered by poor expression of cloned OGT and lack of suitable high-throughput screens. This Communication describes the development an expression system to access large amounts of the catalytic domain of OGT and the implementation of a fluorescence-based substrate analogue displacement assay that has led to the discovery of a set of OGT inhibitors. This work lays the foundation for both structural and functional analysis of the catalytic domain of OGT. 相似文献
87.
Thomson RK Zahariev FE Zhang Z Patrick BO Wang YA Schafer LL 《Inorganic chemistry》2005,44(24):8680-8689
Easily prepared and highly modular organic amide proligands have been used to synthesize a series of new bis(amidate)-bis(amido) Ti and Zr complexes via protonolysis. These complexes have been structurally characterized by NMR spectroscopy and X-ray crystallography. The solid-state molecular structures of these complexes indicate that the amidate ligands bind to the metal centers in an exclusively bidentate fashion, resulting in discrete monomeric species. Geometric isomerism in these species is highly dependent upon the steric characteristics of the proligands utilized in the synthesis. In solution, these complexes are observed to isomerize on the NMR time scale, with one isomer being predominant. Bonding in the bis(amidate)-bis(amido) complexes was investigated by DFT calculations. The geometric isomers predicted by theory matched the experimentally observed results, within experimental error. The orbitals associated with amidate-metal bonding are energetically well below the frontier orbitals. The HOMO in these complexes is a pi orbital associated with amido ligand-to-metal bonding character, while the LUMO in all cases is a vacant d orbital on the metal center. 相似文献
88.
M. Maccoss L. C. Meurer K. Hoogsteen J. P. Springer G. Koo L. B. Peterson R. L. Tolman E. Emini 《Journal of heterocyclic chemistry》1993,30(5):1213-1220
A number of novel C-nucleosides related to purine derivatives are described in which the purine moiety has been replaced by the isosteric heterocycle, 8-aminoimidazo[1,2-α]pyrazine. The nucleosides prepared include the ribo, 3′-deoxy, 2′,3′-dideoxy, and 2′,3′-unsaturated derivatives. These C-nucleosides represent derivatives containing acid stable glycosyl bonds and they can be considered as analogs of adenine- or 3-deazaade-nine-containing nucleosides. Preparation of the parent ribonucleoside was accomplished by reaction of the C-l functionalized sugar, (2ξ)-1-amino-3,6-anhydro-l-deoxy-4,5-O-isopropylidene-7-O-trityl-D-allo-heptitol with 2,3-dichloropyrazine, followed by ring closure to the 8-chloroimidazo[1,2-α]pyrazine nucleoside, conversion to the 8-amino derivative and deblocking. A single crystal X-ray structure of the parent 8-amino-3-(β-D-ribofuranosyl)imidazo[1,2-α]pyrazine is described and the conformation compared to that of formycin. The sugar-modified analogs were prepared by subsequent functional group manipulations on the sugar moiety. Biological evaluation against HIV in H9 T-lymphoid cell culture showed the nucleosides to be devoid of significant antiviral activity compared to DDA. The 3-deazaadenosine analog also demonstrated weak suppression of mouse splenic NK activity toward YAC cells (mouse lymphoma cell targets). The imidazo[1,2-α]pyrazine analog of 3-deazaadenosine showed antiinflammatory activity in vivo in the rat pleurisy carrageenan model in the same range with 3-deazaadenosine. 相似文献
89.
Geng J Ducati C Shephard DS Chhowalla M Johnson BF Robertson J 《Chemical communications (Cambridge, England)》2002,(10):1112-1113
A nanoscale ruthenium/gold bimetallic cluster of clusters has been used as a molecular precursor to produce pure ruthenium nanoparticles (seeds) as catalysts for the growth of carbon nanohorns (CNHs). 相似文献
90.
The chiral surfactant dodecoxycarbonylvaline (DDCV) has proven to be an effective pseudostationary phase for the separation of many enantiomeric pharmaceutical compounds. In this study the elution range and the prediction of octanol-water partitioning for the DDCV micellar system was examined. Through incorporation of DDCV in mixed micelles and unilamellar vesicles, enhancement of the elution range was observed. The mixed micelles contained a second anionic surfactant, sodium dodecyl sulfate (SDS), while the vesicles were composed of DDCV and the cationic surfactant cetyltrimethylammonium bromide (CTAB). Enantioselectivity, as well as other chromatographic and electrophoretic parameters, were compared between the mixed micelles, vesicles, and DDCV micelles. The hydrophobicity of the DDCV system was also evaluated as a predictor of n-octanol-water partition coefficients for 15 beta amino alcohols. The correlation between the logarithm of the retention factor (log k) and log P(ow) for seven hydrophobic beta-blockers and eight beta-agonists were r2 = 0.964 and r2 = 0.814, respectively. 相似文献