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Baffert C Boas JF Bond AM Kögerler P Long DL Pilbrow JR Cronin L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(33):8472-8483
The synthesis, isolation and structural characterization of the sulfite polyoxomolybdate clusters alpha-(D(3h))(C(20)H(44)N)(4){alpha-[Mo(18)O(54)(SO(3))(2)]}CH(3)CN and beta-(D(3d))(C(20)H(44)N)(4){beta-[Mo(18)O(54)(SO(3))(2)]}CH(3)CN is presented. Voltammetric studies in acetonitrile (0.1 M Hx(4)NClO(4), Hx(4)N=tetra-n-hexylammonium) reveal the presence of an extensive series of six one-electron reduction processes for both isomers. Under conditions of bulk electrolysis, the initial [Mo(18)O(54)(SO(3))(2)](4-/5-) and [Mo(18)O(54)(SO(3))(2)](5-/6-) processes produce stable [Mo(18)O(54)(SO(3))(2)](5-) and [Mo(18)O(54)(SO(3))(2)](6-) species, respectively, and the same reduced species may be produced by photochemical reduction. Spectroelectrochemical data imply that retention of structural form results upon reduction, so that both alpha and beta isomers are available at each of the 4-, 5-, and 6-redox levels. However, the alpha isomer is the thermodynamically favored species in both the one- and two-electron-reduced states, with beta-->alpha isomerization being detected in both cases on long time scales (days). EPR spectra also imply that increasing localization of the unpaired electron occurs over the alpha- and beta-[Mo(18)O(54)(SO(3))(2)](5-) frameworks as the temperature approaches 2 K where the EPR spectra show orthorhombic symmetry with different g and hyperfine values for the alpha and beta isomers. Theoretical studies support the observation that it is easier to reduce the alpha cluster than the beta form and also provide insight into the driving force for beta-->alpha isomerization in the reduced state. Data are compared with that obtained for the well studied alpha-[Mo(18)O(54)(SO(4))(2))](4-) sulfate cluster. 相似文献
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M. I. Sykhrannova S. Ya. Khorshev A. N. Tatarnikov E. N. Gladyshev 《Russian Chemical Bulletin》1994,43(8):1405-1407
Based on the dependences v(CO) =a + b* for IR spectra of carbonyi complexes of transition metals, the inductive constants of the organometallic fragments M(CO)
m
Cp
n
and HgM(CO)
m
Cp
n
(M = Co, Mo, Mn, Fe, Re) have been determined. The acceptor properties of the organometallic fragments have been shown to change according to the order of the nucleophilicity of the anions: Fe(CO)2Cp > Re(CO)5 > Mn(CO)5 > Mo(CO)3Cp > Co(CO)4.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1482–1484, August, 1994. 相似文献
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Alvarez CS Bashall A McInnes EJ Layfield RA Mole RA McPartlin M Rawson JM Wood PT Wright DS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(11):3053-3060
The ion-contact complexes [{(eta(5)-Cp)(2)Mn(eta(2):eta(5)-Cp)K}(3)]x0.5 THF (1x0.5 THF) and [{(eta(2)-Cp)(2)(eta(2);eta(5)-MeCp)MnK(thf)}]x2 THF (2x2 THF) and ion-separated complexes [Mg(thf)(6)][(eta(2)-Cp)(3)Mn](2) (3), [Mg(thf)(6)][(eta(2)-Cp)(eta(2)-MeCp)(2)Mn)](2)x0.5 THF (4x0.5 THF), [Mg(thf)(6)][(eta(2)-MeCp)(3)Mn)](2)x0.5 THF (5x0.5 THF) and [Li([12]crown-4)](5)[(eta-Cp)(3)Mn](5) (6) (Cp=C(5)H(5), CpMe=C(5)H(4)CH(3)), have been prepared and structurally characterised. The effects of varying the Cp and CpMe ligands in complexes 1-5 have been probed by variable-temperature magnetic susceptibility measurements and EPR spectroscopic studies. 相似文献
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Bernhardt E Finze M Willner H Lehmann CW Aubke F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(32):8276-8283
The reaction of [Co(2)(CO)(8)] with (CF(3))(3)BCO in hexane leads to the Lewis acid-base adduct [Co(2)(CO)(7)CO--B(CF(3))(3)] in high yield. When the reaction is performed in anhydrous HF solution [Co(CO)(5)][(CF(3))(3)BF] is isolated. The product contains the first example of a homoleptic metal pentacarbonyl cation with 18 valence electrons and a trigonal-bipyramidal structure. Treatment of [Co(2)(CO)(8)] or [Co(CO)(3)NO] with NO(+) salts of weakly coordinating anions results in mixed crystals containing the [Co(CO)(5)](+)/[Co(CO)(2)(NO)(2)](+) ions or pure novel [Co(CO)(2)(NO)(2)](+) salts, respectively. This is a promising route to other new metal carbonyl nitrosyl cations or even homoleptic metal nitrosyl cations. All compounds were characterized by vibrational spectroscopy and by single-crystal X-ray diffraction. 相似文献
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Haidoo Kwen Victor G. Young Jr. Eric A. Maatta 《Angewandte Chemie (International ed. in English)》1999,38(8):1145-1146
A new metathetical route to diazoalkane complexes is described which allows the introduction of such ligands into previously inaccessible environments. The method, which involves the exchange of oxo and [N2CR2] ligands, is illustrated by the preparation of the first diazoalkane–polyoxometalate complex 1 . 相似文献
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Hydrothermal Synthesis and Structure of a New Molybdenum Phosphate: (NH_3CH_2CH_2NH_3)_(2.5)[Mo_5O_(15)(PO_4) (HPO_4)]·7.5H_2O 总被引:2,自引:0,他引:2
1 INTRODUCTION A new class of materials of metal oxide clusters based on anionic molybdenum phosphate frameworks has received much attention as a consequence of their potential applications in catalysis and materials science [1]. As a result, some molybdenum phosphates have been studied [2,3]. Recently we have studied the structure of NaPMO material[4] and the spectrum of multicomponent compound with Keggin struc- ture [5]. Here we report the synthesis and crystal structure of a new… 相似文献
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Jean-François Lemonnier Sébastien Floquet Jérôme Marrot Emmanuel Cadot 《Journal of Cluster Science》2006,17(2):267-282
The novel polyoxothioanion [Mo4S4O4(OH)2(OH2)3pba]2? where pba4? ligand is the 1,3-propylenebis(oxamate), was prepared by reacting Mo12S12O12(OH)12(OH2)6 ring with [Cu-pba]2? in aqueous medium. NaK[Mo4O4(μ-S)4(μ-OH)2(μ-H2O)(H2O)2(pba)] ·7H2O was isolated in the solid state and fully characterized by X-ray diffraction study (tetragonal, P4(2)/m [a=20.4962(4) Å; b=20.4962(4) Å; c=14.7013(5) Å). The molecular structure consists of an arc cycle shape tetranuclear enchainment {Mo4S4O4(OH)2 (OH2)3} closed by a pba4? ligand. The 3-D packing, resulting from the connection between K+ and Na+ and the coordination complex {Mo4-pba]2? is described. The 1H-NMR characterization of the complex in aqueous solution is given. The 1H-NMR spectrum exhibits four signals assigned to four enantiotopic protons of the alkyl chain of the pba4? ligand and is in agreement with crystal structure of the complex [Mo4-pba]2?. The compound was also characterized by infrared spectroscopy. 相似文献
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Hinrichs M Hofbauer FR Klüfers P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(17):4675-4683
With the [Re(CO)(3)Br(3)](2-) ion as a precursor for the Re(I)(CO)(3) fragment, the diols (1R,2R)-cyclohexane-1,2-diol [(1R,2R)-Chxd], anhydroerythritol (AnEryt), and (1S,2S)-cyclopentane-1,2-diol [(1S,2S)-Cptd] form dinuclear monoanions in the salts (NBu(4))[(Re(2)(CO)(6){mu-(1R,2R)-ChxdH(-1)}(3)] (1), [K([18]crown-6)][Re(2)(CO)(6)(mu-OMe)(2)(mu-AnErytH(-1))] (2) and (NBu(4))[Re(2)(CO)(6){mu-(1S,2S)-CptdH(-1)}(3)] (3). The monoanionic diolato ligands in these triply bridged dirhenates(I) are monodentate. Bridging triolato ligation in the trirhenates(I) is supported by the anions of glycerol (Glyc) and methyl beta-D-ribopyranoside (Me-beta-D-Ribp), the latter binding in its (1)C(4) conformation, in (DBUH)(2)[Re(3)(CO)(9)(mu(3)-O)(mu(3)-GlycH(-3))]0.5 MeCN (4 a), (NEt(4))[Re(3)(CO)(9)(mu(3)-OMe)(mu(3)-GlycH(-3))] (4 b) and (DBUH)[Re(3)(CO)(9)(mu(3)-OMe)(mu(3)-(1)C(4)-Me-beta-D-Ribp2,3,4H(-3))] (5). The chiral sugar alcohols L-threitol (L-Thre) and D-arabitol (D-Arab) act as tetra- and pentadentate ligands, respectively, in (NEt(4))[Re(2)(CO)(6)(L-ThreH(-3))]MeCN (6) and (NEt(4))(2)(DBUH)(2)[Re(6)(CO)(18)(D-ArabH(-5))(2)] (7). Complexes 6 and 7 are free of supporting oxo or methoxo ligands and use solely the O-atom pattern of the polyol for the connection of the Re(I)(CO)(3) moieties. 相似文献
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Rodrigo J. Lobo‐Lapidus Bruce C. Gates 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(37):11386-11398
Two carbonyl complexes of rhenium, [HRe(CO)5] and [CH3Re(CO)5], were used to probe surface sites of TiO2 (anatase). These complexes were adsorbed from the gas phase onto anatase powder that had been treated in flowing O2 or under vacuum to vary the density of surface OH sites. Infrared (IR) spectra demonstrate the variation in the number of sites, including Ti+3? OH and Ti+4? OH. IR and extended X‐ray absorption fine structure (EXAFS) spectra show that chemisorption of the rhenium complexes led to their decarbonylation, with formation of surface‐bound rhenium tricarbonyls, when [HRe(CO)5] was adsorbed, or rhenium tetracarbonyls, when [CH3Re(CO)5] was adsorbed. These reactions were accompanied by the formation of water and surface carbonates and removal of terminal hydroxyl groups associated with Ti+3 and Ti+4 ions on the anatase. Data characterizing the samples after adsorption of [HRe(CO)5] or [CH3Re(CO)5] determined a ranking of the reactivity of the surface OH sites, with the Ti+3? OH groups being the more reactive towards the rhenium complexes but the less likely to be dehydroxylated. The two rhenium pentacarbonyl probes provided complementary information, suggesting that the carbonate species originate from carbonyl ligands initially bonded to the rhenium and from hydroxyl groups of the titania surface, with the reaction leading to the formation of water and bridging hydroxyl groups on the titania. The results illustrate the value of using a family of organometallic complexes as probes of oxide surface sites. 相似文献
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