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41.
Michael I. Bruce Ernst Horn Janis G. Matisons Michael R. Snow 《Journal of organometallic chemistry》1985,286(2):271-287
The reactions of Os3(μ-H)2(CO)10 with a series of Group IB metal acetylide-tertiary phosphine complexes are described. Whereas the compounds M(C2C6F5)(PPh3) (M = Cu, Ag, Au) afforded the complexes MOs3(μ-CHCHC6F5)(CO)10(PPh3) cleanly and in high yield, complex mixtures of products were obtained from reactions of the analogous phenylacetylides. The complexes MOs3(μ-CHCHPh)(CO)10(PPh3), MOs3(μ-CHCHPh)(CO)9(PPh3)2 and MOs3(μ-H)(CO)10(PPh3) (of known structure), and MOs3(μ-CHCHPh)(CO)9(PPh3)2 and HMOs3(CHCPh)(CO)8 (of unknown structure) were characterised; Au(C2Ph)(PMe3) afforded similar derivatives. The reactions proceed by oxidative-addition and hydrogen migration steps; MP bond cleavage reactions also occur to a small extent. The molecular structures of AuOs3(μ-CHCHC6R5)(CO)10(PPh3) (R = F or H) were determined by X-ray analyses. For R = F, crystals are triclinic, space group P with a 9.081(2), b 13.291(2), c 17.419(2) Å, α 84.49(1), β 76.20(2), γ 75.81(2)° and Z = 2; 4622 observed data [I > 2.5σ(I)] were refined to R = 0.027, RW = 0.031. For R = H, crystals are triclinic, space group P, with a 9.403(4), b 13.448(3), c 13.774(4) Å, α 83.34(2), β 88.66(3), γ 70.21(3)°, and Z = 2; 4405 observed data [I > 2.5σ(I)] were refined to R = 0.030, RW = 0.033. The two molecules differ in the orientation of the Ph rings of the PPh3 groups, but are otherwise similar to Os3(μ-H)(μ-CHCHBut)(CO)10 with the μ-H ligand replaced by the isolobal μ-Au(PPh3) group. 相似文献
42.
Characterization of inclusion complexes of betamethasone-related steroids with cyclodextrins using high-performance liquid chromatography 总被引:1,自引:0,他引:1
HPLC was used to study the inclusion complexes formed between various beta- and gamma-cyclodextrins and a series of corticosteroids related to betamethasone. Apparent association constants were measured in acetonitrile-water for a set of 13 steroids. An increase in the stability of the steroid-cyclodextrin complex is observed at lower concentrations of acetonitrile. The effects of the nature of the halide at the 9-position, the location of a double bond within the C-ring, substitution at the 9- and 11-positions, and modification of the D-ring of the steroid backbone were studied. The 11- and 17-positions were found to be critically involved in the inclusion process. Larger apparent association constants were obtained with gamma-cyclodextrin (gamma-CD) than with beta-cyclodextrin (beta-CD) due to the increased diameter of the gamma-CD cavity. Van't Hoff plots were constructed to examine the thermodynamic properties of the inclusion process. Plots constructed using retention factors were found to be nonlinear when gamma-CD was present in the mobile phase. This is due to an increase in the strength of the inclusion complex as temperature decreases. Plots constructed using apparent association constants were linear, indicating that the mechanism of inclusion does not change over the range of temperatures studied (10 to 80 degrees C). Enthalpy-entropy compensation was observed for 11 of the 13 steroids studied. The usefulness of cyclodextrins to achieve the separation of steroids in HPLC is discussed and a practical application for the analysis of a steroid and three potential impurities is described. 相似文献
43.
Michael I. Bruce Andrew Catlow Mark G. Humphrey George A. Koutsantonis Michael R. Snow Edward R.T. Tiekink 《Journal of organometallic chemistry》1980,338(1):59-80
A reinvestigation of the reaction between C2(CO2Me)2 and RuH(PPh3)2(η-C5H5) and some related complexes is reported. Initial cis addition is followed by conversion into the trans isomer. In the case of the bis-(PPh3) complex, isomerisation is followed by chelation of the ester CO group with concomitant displacement of one PPh3ligand. The resulting chelate complex reacts with CO or CNBut to give the (Z)-RuC(CO2Me)CH(CO2Me) complexes; the (E)-isomer of the carbonyl complex is obtained by addition of C2(CO2Me)2to RuH(CO)(PPh3)(η-C5H5). The 1Hand 13C NMR spectra are not a reliable guide to assignment of the stereochemistry of the vinyl group. Other products isolated from the initial reaction are the bis-insertion product CH(CO2Me)} -(PPh3)(η-C5H5) and the 1/2 PPh3/C2(CO2Me)2 adduct. The molecular structures of Ru{(Z)-C(CO2Me)CH(CO2Me)}(CO)(PPh3(η-C5H5) · 0.5EtOH, Ru{(E)-C(C2Me)CH(CO2Me)}(dppe)(η-C5H5) and CH(CO2Me)}(PPh3)(η-C5H5) have been determined. The cis isomer is monoclinic, space group P21,with a 9.328(8), b 17.385(10), c 10.356(7) Å, β 101.78(3)° and Z = 2; 2107 data with I ≥ 2.5σ(I) were refined to R = 0.076 Rw = 0.085. The trans isomer is triclinic, space group P, with a 10.404(7) b 11.221(6), c 13.230(9) Å, α 92.67(5), β 110.56(5), γ 106.21(5)° and Z = 2; 2520 data with I ≥ 2.5σ(I) were refined to R = 0.055 Rw = 0.068. The butadienyl complex is monoclinic, space group P21/a, with a 19.655(8), b 8.674(4), c 21.060(5) Å, β 116.22(3)° and Z = 4; 2724 data with I ≥ 2.5σ(I) were refined to R = 0.042, Rw = 0.047. 相似文献
44.
E. K. Squire P. A. Snow P. St. J. Russell L. T. Canham A. J. Simons C. L. Reeves 《Journal of luminescence》1998,80(1-4):125-128
Experimental and theoretical techniques are used to examine the effects of microstructuring on the optical properties of multilayer, single and multiple microcavity structures fabricated from porous silicon. Measurements of the reflectivity and photoluminescence spectra of three multilayer samples are presented. The results are modelled using a transfer matrix technique including a negative absorption term to represent the effect of spontaneous emission which gives luminescence. The emitted light is strongly controlled by the optical modes of the structures and very good agreement is observed between theory and experiment. 相似文献
45.
M. Bonesini E. Bonvin P. S. L. Booth R. Bopp L. J. Carroll A. J. Cass D. Cavalli S. U. Chung G. Costa M. Donnat P. A. Dorsaz E. Durieux M. E. J. Feliks J. R. Fischer L. Fluri F. Gianotti S. Jack J. N. Jackson M. Kelly M. N. Kienzle-Focacci R. Lucock J. G. Lynch L. Mandelli M. Martin L. Mathys A. Maxwell M. Mazzanti P. J. Negus L. Perini D. Perrin G. Polesello R. Poultney W. H. Range L. Rosselet S. W. Snow A. S. Thompson R. M. Turnbull M. Werlen WA -Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,42(4):527-532
The inclusive cross sections for η production by the interactions of 280 GeV/c momentum π?, π+, and proton beams in hydrogen have been measured. The kinematical range covered is ?0.45<x F <0.45, and 4.0<P T <7.0 GeV/c for Feynmanx F and transverse momentum respectively. The η to π0 cross section ratios are given for the three reactions. The ratio of π? p to π+ p cross sections for η production in the above kinematic ranges is 1.22±0.08±0.11. 相似文献
46.
Ammar R Baringer P Coppage D Davis R Kelly M Kwak N Lam H Ro S Kubota Y Lattery M Nelson JK Perticone D Poling R Schrenk S Wang R Alam MS Kim IJ Nemati B Romero V Sun CR Wang P Zoeller MM Crawford G Fulton R Gan KK Kagan H Kass R Lee J Malchow R Morrow F Sung MK Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Skubic P Snow J Bortoletto D Brown DN Dominick J McIlwain RL Miller DH Modesitt M Shibata EI Schaffner SF Shipsey IP Battle M Ernst J Kroha H Roberts S Sparks K Thorndike EH 《Physical review D: Particles and fields》1992,45(11):3976-3985
47.
48.
Michael I. Bruce Ernst Horn Omar Bin Shawkataly Michael R. Snow 《Journal of organometallic chemistry》1985,280(2):289-298
Deprotonation (K[HBBu3s]) of HRu3(μ3-C2But)(CO)9, followed by reaction of the anion with [O{Au(PPh3)}3][BF4], afforded the known complex Ru3Au(μ3-C2But)(CO)9 (9%), the vinylidene cluster Ru3Au2(μ3-CCHBut)(CO)9(PPh3)2 (16%) and the hexanuclear Ru3Au3(C2But)(CO)8(PPh3)3 (3%). The X-ray structure of the pentanuclear complex shows an asymmetric trigonal-bipyramidal Ru3Au2 core (Ru, Au at the apices) with the Ru3 face bridged by a t-butylvinylidene ligand, being σ-bonded to Ru(1) and Ru(3), and η2-coordinated to Ru(2). Crystals are monoclinic, space group P21/n with a 19.121(3), b 13.109(3), c 23.649(4) Å, β 106.76(2)° and Z = 4. The structure was solved using 4405 observed diffractometer data, and refined to R 0.044, Rw 0.047. 相似文献
49.
Michael I. Bruce E. Horn M.R. Snow M.L. Williams 《Journal of organometallic chemistry》1984,276(2):c53-c57
Hydrogenation of [Ru3(CO)10(L2)] (L2 = dppm or dpam) affords [HRu3(μ3-PhECH2EPh2)(CO)9] (E = P or As), which is deprotonated by K[HBBu3s] . Reactions of the anions with [PhN2] [PF6] give [Ru3(μ-N2Ph)(μ3-PhECH2EPh2)(CO)9], which undergo facile cyclometallation reactions when heated, as revealed by an X-ray structure of the title complex. 相似文献
50.