Activation of H<sub>2</sub>O<sub>2</sub> over Zr(IV). Insights from Model Studies on Zr-Monosubstituted Lindqvist Tungstates
作者:Nataliya V. Maksimchuk、Vasilii Yu. Evtushok、Olga V. Zalomaeva、Gennadii M. Maksimov、Irina D. Ivanchikova、Yuriy A. Chesalov、Ilia V. Eltsov、Pavel A. Abramov、Tatyana S. Glazneva、Vadim V. Yanshole、Oxana A. Kholdeeva、R. John Errington、Albert Solé-Daura、Josep M. Poblet、Jorge J. Carbó
DOI:10.1021/acscatal.1c02485
日期:2021.8.20
(Bu4N)2[W5O18Zr(H2O)3] (1) and (Bu4N)6[W5O18Zr(μ-OH)}2] (2), have been employed as molecular models to unravel the mechanism of hydrogen peroxide activation over Zr(IV) sites. Compounds 1 and 2 are hydrolytically stable and catalyze the epoxidation of C═C bonds in unfunctionalized alkenes and α,β-unsaturated ketones, as well as sulfoxidation of thioethers. Monomer 1 is more active than dimer2. Acid
Zr-单取代的 Lindqvist 型多金属氧酸盐 (Zr-POM),(Bu 4 N) 2 [W 5 O 18 Zr(H 2 O) 3 ] ( 1 ) 和 (Bu 4 N) 6 [W 5 O 18 Zr( μ-OH)} 2 ] ( 2 ),已被用作分子模型来揭示过氧化氢在 Zr(IV) 位点上的活化机制。化合物1和2具有水解稳定性,可催化未官能化烯烃和 α,β-不饱和酮中 C=C 键的环氧化以及硫醚的磺化氧化。单体1比二聚体2更活跃。酸添加剂大大加速了氧化反应,并将氧化剂利用效率提高到>99%。产物分布表明异裂氧转移机制,该机制涉及在 Zr-POM 和 H 2 O 2相互作用时形成的亲电氧化物质。1和2与 H 2 O 2的相互作用以及由此产生的过氧衍生物已通过 UV-vis、FTIR、拉曼光谱、HR-ESI-MS 和组合 HPLC-ICP-原子发射光谱技术进行了研究。一个之间的相互作用17
Synthesis and Reactivity of the Methoxozirconium Pentatungstate (<i><sup>n</sup></i>Bu<sub>4</sub>N)<sub>6</sub>[{(μ-MeO)ZrW<sub>5</sub>O<sub>18</sub>}<sub>2</sub>]: Insights into Proton-Transfer Reactions, Solution Dynamics, and Assembly of {ZrW<sub>5</sub>O<sub>18</sub>}<sup>2</sup><sup>-</sup> Building Blocks
作者:R. John Errington、Sagar S. Petkar、Paul S. Middleton、William McFarlane、William Clegg、Robert A. Coxall、Ross W. Harrington
DOI:10.1021/ja0725495
日期:2007.10.1
and n = 1 for 4-8, while 1H and 17O NMR studies of hydrolysis of 1 revealed the formation of an intermediate [(mu-MeO)(mu-HO)(ZrW5O18)2]6-. Electrospray ionization mass spectrometry of 1 and 3 illustrated the robust nature of the ZrW5O18 framework, and X-ray crystal structure determinations showed that steric interactions between ligands X and the ZrW5O18 surface are important. The coordination number
Hydrates of Organic Compounds. VII. The Effect of Anions on the Formation of Clathrate Hydrates of Tetrabutylammonium Salts
作者:Haruo Nakayama
DOI:10.1246/bcsj.56.877
日期:1983.3
Phasediagrams of the binary mixtures of tetrabutylammonium salt [(n-C4H9)4N]nX (X=NO2, NO3, BrO3, ClO3, IO3, ClO4, MnO4, and NCS for n=1; X=CO3, SO4, WO4, and CrO4 for n=2; and X=PO4 for n=3) with water were determined over the temperature range between −10 and +50 °C. From these diagrams the following results were obtained: (1) the formation of a clathrate-like hydrate for salts having such anions
Adducts of the Lewis acid [B(C6F5)3] with transition metal oxo compounds
作者:Georgina Barrado、Linda Doerrer、Malcolm L. H. Green、Michael A. Leech
DOI:10.1039/a809519a
日期:——
The oxo anions [WO4]2– and [ReO4]– react with the Lewis acid molecule [B(C6F5)3] to give the tris-adduct [WOOB(C6F5)3}3]2– or the mono adduct [ReO3OB(C6F5)3}]– respectively. The crystal structure of the salt [nPr4N]2[WOOB(C6F5)3}3] has been determined. The η-cyclopentadienyl-oxo compounds [Re(η-C5R5)O3] (where R = H or Me) react with [B(C6F5)3] giving the mono adducts [(η-C5R5)ReO2OB(C6F5)3}] and the crystal structure of the compound where R = H has been determined. The triazacyclononane compounds [LMO3] (where L = N,N′,N″-trimethyl-1,4,7-triazacyclononane and M = Mo or W) with [B(C6F5)3] give the mono adducts [LMO2OB(C6F5)3}] and the crystal structure of the tungsten compound is reported. The compound [ReHB(pz)3}O3] [where HB(pz)3} = hydridotris(1-pyrazolyl) borate] and [B(C6F5)3] gives the mono adduct [HB(pz)3ReO2OB(C6F5)3}].
氧化阴离子 [WO4]2- 和 [ReO4]- 与路易斯酸分子 [B(C6F5)3] 反应,分别生成三加合物 [WOOB(C6F5)3}3]2- 或单加合物 [ReO3OB(C6F5)3}]-。盐 [nPr4N]2[WOOB(C6F5)3}3] 的晶体结构已经确定。η-环戊二烯氧化合物 [Re(η-C5R5)O3](其中 R = H 或 Me)与 [B(C6F5)3] 反应生成单加合物 [(η-C5R5)ReO2OB(C6F5)3}],其中 R = H 的化合物的晶体结构已经确定。三氮杂环壬烷化合物 [LMO3](其中 L = N,N′,N″-三甲基-1,4,7-三氮杂环壬烷,M = Mo 或 W)与 [B(C6F5)3] 生成单加合物 [LMO2OB(C6F5)3}],并报告了钨化合物的晶体结构。化合物 [ReHB(pz)3}O3] [其中 HB(pz)3} = 三(1-吡唑基)硼酸氢化物] 和 [B(C6F5)3] 得到单加合物 [HB(pz)3ReO2OB(C6F5)3}]。
Alkoxide hydrolysis as a route to early transition-metal polyoxometalates: synthesis and crystal structures of heteronuclear hexametalate derivatives
作者:William Clegg、Mark R. J. Elsegood、R. John Errington、Joanne Havelock
DOI:10.1039/dt9960000681
日期:——
Oxygen-17 NMR studies indicated that the hexametalates [MW5O19]n– or their derivatives [(MeO)MW5O18](n–1)–(M = Ti, Zr, V, Nb, Ta, Mo or W) can be obtained by hydrolysis of the appropriate mixture of metal alkoxides in the presence of M′O42–(M′= W or Mo) with remarkable selectivity in some cases, giving a very efficient method of preparing 17O-enriched polyoxometalates. The crystal structure of [NBun4]3[(MeO)TiW5O18]·0.5MeCN shows the terminal Ti–OMe bond in the anion to have Ti–O 1.760(10)Å and Ti–O–C 150.1(12)° and also reveals W–O bridging bond length alternations due to the substitution of Ti(OMe)3+ for WO4+ in the [W6O19]2– structure. Hydrolysis of [NBun4]2[(MeO)NbW5O18] gives [NBun4]4[(NbW5O18)2O] and the crystal structure revealed two eclipsed NbW5O18 oxide fragments joined by a strictly linear Nb–O–Nb linkage with Nb–O 2.264(8)Å.