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排序方式: 共有458条查询结果,搜索用时 15 毫秒
61.
Simon G. Bott Jian Cheng Wang Michael G. Richmond 《Journal of chemical crystallography》1999,29(5):603-608
The cobalt cluster PhCCo3(CO)9 reacts with the bis(phosphanyl)hydrazine ligand bis(diphenylphosphino)dimethylhydrazine (dppdmh) in CH2Cl2 with added Me3NO to give the monosubstituted cluster PhCCo3(CO)8[Ph2PP(O)PPh2] as the major isolable product. The solid-state structure of this new cluster was unequivocally established by X-ray diffraction analysis, which has confirmed the presence of a noncoordinated (O)PPh2 moiety. PhCCo3(CO)8[Ph2PP(O)Ph2] crystallizes in the triclinic space group P
, a = 12.036(2), b = 12.037(2), c = 15.124(3) Å, = 84.82(1)°, = 89.44(2)°, = 60.09(1)°, V = 1890.0(6) Å3, Z = 2, and dcalc = 1.540 g/cm3. 相似文献
62.
Huafeng Shen Jian Cheng Wang Simon G. Bott Michael G. Richmond 《Journal of chemical crystallography》1997,27(11):649-656
Thermolysis of Ru3(CO)12 with 2,3-bis(diphenylphosphino)maleic anhydride (bma) in toluene solution gives the new compounds Ru3(CO)10(bma) (2), Ru2(CO)6(bma) (3), and (4). All compounds have been isolated and characterized in solution by IR and31P NMR spectroscopy. The solid-state structures of2, as the monohydrate, and4 were established by X-ray crystallography. Ru3(CO)10(bma)·H2O crystallizes in the monoclinic space groupC2/c,a=12.741(2) Å,b=19.548(2) Å,c=32.973(4) Å, β=96.847(9)°,V=8154(2) Å3,Z=8,d calc=1.740 g cm?3;R=0.046,R w =0.051 for 2541 observed reflections withl>3σ(l). The bma ligand in2 is bound to the triruthenium frame in a bridging fashion, with equatorially disposed PPh2 groups. The X-ray structure of2 reveals an extreme twisting of the maleic anhydride ring away from the plane defined by the plane of the three ruthenium atoms, along with a significant lengthening of the maleic anhydride C=C π bond. crystallizes in the monoclinic space groupP21/c,a=9.3113(5) Å,b=18.164(1) Å,c=20.097(1) Å, β-102.021(4)°,V=3324.5(3) Å3,Z=4,d calc=1.671 g cm?3;R=0.024,R w =0.030 for 3499 observed reflections withl>3σ(l). The presence of the μ2 moiety and P?C (maleic anhydride) bond cleavage attendant in the formation of4 are confirmed by X-ray analysis. The relationship of the compounds3 and4 to the dimeric compounds Ru2(CO)6(bpcd) and [where bpcd=4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione] is discussed. Independent studies dealing with Ru3(CO)10(bma) (bridging isomer) have shown that cluster2 is stable in toluene solution at elevated temperature and does not afford compounds3 and4, suggesting the intermediacy of the putative chelating isomer of Ru3(CO)10(bma) (1) as the source of3 and4. 相似文献
63.
William H. Watson Guanmin Wu Michael G. Richmond 《Journal of chemical crystallography》2004,34(10):709-716
The reaction of p-toluenethiol with 4,5-dichloro-4-cyclopenten-1,3-dione in 1,2-dichloroethane with added DBU affords good yields of the new bidentate sulfide ligand 4,5-bis(p-tolylthio)-4-cyclopenten-1,3-dione. The title compound was isolated by column chromatography and characterized in solution by IR and NMR spectroscopies. The solid-state structure of RC=CRC(O)CH2C(O) (where R = p-tolylthio) was solved by X-ray crystallography. 4,5-Bis(p-tolylthio)-4-cyclopenten-1,3-dione crystallizes in the monoclinic space group P2
1/c, a = 14.203(3) Å, b = 6.181(1) Å, c = 20.372(4) Å, = 106.111(3)°, V = 1718.1(6) Å3, Z = 4, and d
calc = 1.316 mg/m3; R = 0.0743, R
w = 0.1693 for 3958 reflections with I > 2(I). The redox properties of 4,5-bis(p-tolylthio)-4-cyclopenten-1,3-dione have been examined by cyclic voltammetry in CH2Cl2 solution, where a quasireversible reduction wave at –1.10 V was found. The reduction behavior is discussed relative to the nature of the LUMO level, which has been determined by extended Hückel MO calculations. The redox chemistry and the LUMO of our bidentate sulfide ligand are contrasted with the known redox chemistry and the LUMO composition of the corresponding bidentate phosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). 相似文献
64.
William H. Watson Bhaskar Poola Jin Liu Michael G. Richmond 《Journal of chemical crystallography》2007,37(5):349-358
The reaction of the pincer diphosphine ligand 4,6-bis(diphenylphosphinomethyl)-m-xylene (dppx) with the metal cluster compounds PhCCo3(CO)9 and Ru6(μ6-C)(CO)17 has been explored. Both clusters react with dppx to afford the simple substitution products [PhCCo3(CO)8]2(dppx) and [Ru6(μ6-C)(CO)16]2(dppx), where two cluster units are tethered by the pincer ligand. The molecular structures of the title products and the
2:1 cluster-pincer ligand stoichiometry have been established by X-ray crystallography. The stability of [PhCCo3(CO)8]2(dppx) and [Ru6(μ6-C)(CO)16]2(dppx) has been investigated under gentle thermolysis conditions (ca. 55–65°C). Both dppx-substituted clusters are unstable
with [PhCCo3(CO)8]2(dppx) decomposing and [Ru6(μ6-C)(CO)16]2(dppx) transforming into the diphosphine-bridged cluster Ru6(μ6-C)(CO)15(μ-dppx) as the major observable product. The identity of the latter cluster has been ascertained by IR and NMR spectroscopies
and mass spectrometry. 相似文献
65.
Simon G. Bott Kaiyuan Yang Michael G. Richmond 《Journal of chemical crystallography》2004,34(2):127-133
Treatment of the diphosphine ligand 1,2-bis(diphenylphosphino)cyclobutenedione (bpcbd) with the THF adduct fac-BrRe(CO)3(THF)2 at room temperature furnishes the new dirhenium compound [BrRe(CO)3]2(bpcbd) instead of the expected mononuclear compound fac-BrRe(CO)3(bpcbd). [BrRe(CO)3]2(bpcbd) was characterized in solution by IR spectroscopy, and the solid-state structure was solved by X-ray crystallography. [BrRe(CO)3]2(bpcbd), as the CH2Cl2 solvate, crystallizes in the space group P
, a = 11.173(1), b = 13.362(1), c = 15.250(1) Å, = 108.973(7)°, = 99.477(8)°, = 110.466(7)°, V = 1915.0(3) Å3, Z = 2, and d
calc = 2.143 g-cm–3. The structure of [BrRe(CO)3]2(bpcbd) consists of two rhenium centers that are six-coordinate and possess nearly ideal octahedral geometry. The two Re(CO)3 units are linked together by the bridging diphosphine ligand and two bridging bromide groups. 相似文献
66.
Michael P. Castellani William G. Smith Nimish G. Patel Simon G. Bott Michael G. Richmond 《Journal of chemical crystallography》1999,29(5):609-617
The reaction between the tricobalt cluster Co3(CO)9(3-CCl) (1) and AlCl3, followed by treatment with ethyl diazoacetate, N2CHCO2Et, affords a complex mixture of products in low yields. Column chromatography has allowed the isolation of the four cluster compounds Co3(CO)9(3-CH) (2), Co3(CO)9(3-CCO2Et) (3), Co3(CO)9(3-CCH2CO2Et) (4), and [Co3(CO)9(3-CCHCO2Et)]2 (5). Clusters 4 and 5 are new and have been fully characterized in solution by IR and 1H NMR spectroscopy. The molecular structures of clusters 3–5 have also been determined by single-crystal X-ray diffraction analysis. Co3(CO)9(3-CCO2Et) crystallizes in the triclinic space group P
, a = 8.8393(5), b = 14.727(1), c = 15.272(1) Å, = 93.361(6), = 105.509(5)°, = 100.336(6)°, V = 1872.6(2) Å3, Z = 4, and d
calc = 1.823 g/cm3. Co3(CO)9(3-CCH2CO2Et) crystallizes in the monoclinic space group P21/n, a = 9.3806(7), b = 9.2617(8), c = 22.455(2) Å, = 94.483(7)°, V = 1944.9(3) Å3, Z = 4, and d
calc = 1.803 g/cm3. [Co3(CO)9(3-CCHCO2Et)]2 crystallizes in the monoclinic space group C2/c, a = 21.585(2), b = 8.7977(7), c = 20.784(1) Å, = 104.807(6)°, V = 3815.8(5) Å3, Z = 4, and d
calc = 1.835 g/cm3. Plausible pathways leading to the formation of clusters 2,
4, and 5 are discussed. 相似文献
67.
Huafeng Shen Jian Cheng Wang Simon G. Bott Michael G. Richmond 《Journal of chemical crystallography》1994,27(11):649-656
Thermolysis of Ru3(CO)12 with 2,3-bis(diphenylphosphino)maleic anhydride (bma) in toluene solution gives the new compounds Ru3(CO)10(bma) (2), Ru2(CO)6(bma) (3), and
(4). All compounds have been isolated and characterized in solution by IR and31P NMR spectroscopy. The solid-state structures of2, as the monohydrate, and4 were established by X-ray crystallography. Ru3(CO)10(bma)·H2O crystallizes in the monoclinic space groupC2/c,a=12.741(2) ?,b=19.548(2) ?,c=32.973(4) ?, β=96.847(9)°,V=8154(2) ?3,Z=8,d
calc=1.740 g cm−3;R=0.046,R
w
=0.051 for 2541 observed reflections withl>3σ(l). The bma ligand in2 is bound to the triruthenium frame in a bridging fashion, with equatorially disposed PPh2 groups. The X-ray structure of2 reveals an extreme twisting of the maleic anhydride ring away from the plane defined by the plane of the three ruthenium
atoms, along with a significant lengthening of the maleic anhydride C=C π bond.
crystallizes in the monoclinic space groupP21/c,a=9.3113(5) ?,b=18.164(1) ?,c=20.097(1) ?, β-102.021(4)°,V=3324.5(3) ?3,Z=4,d
calc=1.671 g cm−3;R=0.024,R
w
=0.030 for 3499 observed reflections withl>3σ(l). The presence of the μ2 moiety and P−C (maleic anhydride) bond cleavage attendant in the formation of4 are confirmed by X-ray analysis. The relationship of the compounds3 and4 to the dimeric compounds Ru2(CO)6(bpcd) and
[where bpcd=4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione] is discussed. Independent studies dealing with Ru3(CO)10(bma) (bridging isomer) have shown that cluster2 is stable in toluene solution at elevated temperature and does not afford compounds3 and4, suggesting the intermediacy of the putative chelating isomer of Ru3(CO)10(bma) (1) as the source of3 and4. 相似文献
68.
William H. Watson Guanmin Wu Michael G. Richmond 《Journal of organometallic chemistry》2008,693(8-9):1439-1448
Me3NO activation of the tetrairidium cluster Ir4(CO)12 (1) in presence of the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) furnishes the bpcd-substituted clusters Ir4(CO)10(bpcd) (3) and Ir4(CO)8(bpcd)2 (4) as the minor and major products, respectively. Cluster 3 has been isolated as the sole observable product from the reaction of [Ir4(CO)11Br][Et4N] (2) with bpcd in presence of AgBF4 at room temperature. Both 3 and 4 have been isolated and fully characterized in solution by spectroscopic methods. The solid-state structure of 3 reveals that the ancillary bpcd ligand is bound to a single iridium center, with chelating and bridging bpcd ligands found in the X-ray structure of cluster 4. Cluster 4 is unstable at room temperature and slowly loses CO to afford the hydride-bridged cluster HIr4(CO)4(μ-CO)3(bpcd)[μ-PhP(C6H4)CC(PPh2)C(O)CH2C(O)] (5). Cluster 5 has been fully characterized in solution by IR and NMR spectroscopies, and the C–H bond activation attendant in the ortho metalation step is shown to occur regioselectively at one of the aryl groups associated with the bridging bpcd ligand. The redox properties of clusters 3–5 have been explored and the electrochemical behavior discussed with respect to extended Hückel MO calculations and related diphosphine-substituted cluster compounds prepared by our groups. 相似文献
69.
Nitric acid plays an important role in the heterogeneous chemistry of the atmosphere. Reactions involving HNO(3) at aqueous interfaces in the stratosphere and troposphere depend on the state of nitric acid at these surfaces. The vapor/liquid interface of HNO(3)-H2O binary solutions and HNO(3)-H(2)SO(4)-H2O ternary solutions are examined here using vibrational sum frequency spectroscopy (VSFS). Spectra of the NO2 group at different HNO(3) mole fractions and under different polarization combinations are used to develop a detailed picture of these atmospherically important systems. Consistent with surface tension and spectroscopic measurements from other laboratories, molecular nitric acid is identified at the surface of concentrated solutions. However, the data here reveal the adsorption of two different hydrogen-bonded species of undissociated HNO(3) in the interfacial region that differ in their degree of solvation of the nitro group. The adsorption of these undissociated nitric acid species is shown to be sensitive to the H2O:HNO(3) ratio as well as to the concentration of sulfuric acid. 相似文献
70.
The interaction of EDTA with barium sulfate 总被引:1,自引:0,他引:1
Jones F Jones P Ogden MI Richmond WR Rohl AL Saunders M 《Journal of colloid and interface science》2007,316(2):553-561
Ethylenediaminetetraacetic acid (EDTA) is a known complexing agent that interacts with a host of cations. In this paper, various techniques are used to elucidate the mechanism of interaction between EDTA and barium sulfate surfaces. It is shown that complexation with metal ions is not sufficient to explain the inhibition of barite crystallization but that other processes such as chemisorption must also occur. EDTA is shown to always adsorb as the mono-protonated species - suggesting that the molecule is able to lose a proton when it adsorbs at lower pH. Molecular modelling shows that the interaction of the surface barium ions with the carboxylate group is an important one. Finally, in situ turbidity measurements provide information about the mechanism of nucleation/growth modification. It is found that the EDTA molecule inhibits barium sulfate nucleation and that this could be its primary means of inhibiting precipitation of barium sulfate. 相似文献