<sup>183</sup>
W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
作者:Julius Hillenbrand、Markus Leutzsch、Christopher P. Gordon、Christophe Copéret、Alois Fürstner
DOI:10.1002/anie.202009975
日期:2020.11.23
Triarylsilanolates are privileged ancillary ligands for molybdenum alkylidyne catalysts for alkynemetathesis but lead to disappointing results and poor stability in the tungsten series. 1H,183W heteronuclear multiple bond correlation spectroscopy, exploiting a favorable 5J‐coupling between the 183W center and the peripheral protons on the alkylidyne cap, revealed that these ligands upregulate the Lewis acidity
三芳基硅烷醇盐是用于炔复分解的钼亚烷基催化剂的优先辅助配体,但在钨系列中导致令人失望的结果和较差的稳定性。1 H, 183 W 异核多重键相关光谱,利用183 W 中心与烷叉帽上的外围质子之间有利的5 J耦合,揭示了这些配体将路易斯酸度上调到一定程度,使得环丁二烯钨在最初形成[2+2]环加成步骤过度稳定并且催化周转停止。以183 W NMR 位移作为中心原子路易斯酸度的代表,并通过烷叉单元的化学位移张量分析,重新审视了配体设计,并制备了更强的 π 供体全醇盐配体。新的膨胀螯合物具有缓和的路易斯酸度,并且在速率和官能团相容性方面优于带有单齿叔丁氧基配体的经典Schrock催化剂。
Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex
作者:Henrike Ehrhorn、Janin Schlösser、Dirk Bockfeld、Matthias Tamm
DOI:10.3762/bjoc.14.220
日期:——
The catalytic alkyne metathesis activity of these metal complexes was determined in the self-metathesis, ring-closing alkyne metathesis and cross-metathesis of internal and terminal alkynes, revealing an almost equally high metathesis activity for the bimetallic tungstencomplex W2F3 and the alkylidyne complex W Ph F3. In contrast, Mo2F6 displayed no significant activity in alkyne metathesis.
Partially fluorinated oxo-alkoxide tungsten(<scp>vi</scp>) complexes as precursors for deposition of WO<sub>x</sub> nanomaterials
作者:Richard O. Bonsu、Hankook Kim、Christopher O'Donohue、Roman Y. Korotkov、K. Randall McClain、Khalil A. Abboud、Ashley A. Ellsworth、Amy V. Walker、Timothy J. Anderson、Lisa McElwee-White
DOI:10.1039/c4dt00407h
日期:——
The partiallyfluorinated oxo-alkoxide tungsten(VI) complexes WO(OR)4 [4; R = C(CH3)2CF3, 5; R = C(CH3)(CF3)2] have been synthesized as precursors for chemical vapour deposition (CVD) of WOx nanocrystalline material. Complexes 4 and 5 were prepared by salt metathesis between sodium salts of the fluoroalkoxides and WOCl4. Crystallographic structure analysis allows comparison of the bonding in 4 and
Classifying and Understanding the Reactivities of Mo-Based Alkyne Metathesis Catalysts from <sup>95</sup>Mo NMR Chemical Shift Descriptors
作者:Zachariah J. Berkson、Lukas Lätsch、Julius Hillenbrand、Alois Fürstner、Christophe Copéret
DOI:10.1021/jacs.2c06252
日期:2022.8.24
that NMR chemical shifts are powerful descriptors, though previous studies have mostly focused on ligand-based NMR descriptors. Here, we show in the context of alkyne metathesis that 95Mo chemical shift tensors encode detailed information on the electronic structure of these catalysts. Analysis by first-principles calculations of 95Mo chemical shift tensors extracted from solid-state 95Mo NMR spectra
最活跃的炔烃复分解催化剂依赖于定义明确的 Mo 亚烷基,X 3 Mo≡CR (X = OR),特别是最近开发的带有硅烷醇配体组的冠层催化剂家族。最近了解催化剂反应模式的努力表明 NMR 化学位移是强大的描述符,尽管以前的研究主要集中在基于配体的 NMR 描述符上。在这里,我们在炔烃复分解的背景下表明,95 Mo 化学位移张量编码了有关这些催化剂电子结构的详细信息。从固态95中提取的95 Mo 化学位移张量的第一性原理计算分析Mo NMR 光谱显示化学位移值与 HOMO 和 LUMO 的能量直接相关,这两个分子轨道涉及关键的 [2 + 2]-环加成步骤,因此将95 Mo 化学位移与反应性联系起来。特别是,95 Mo 化学位移是由配体电负性(σ-供体)和通过 Mo-O π 相互作用的电子离域驱动的,从而解释了硅醇盐冠层催化剂的反应模式。这些结果进一步激发了对过渡金属核磁共振特征及其与电子结构和反应性关系的探索。
Dioxo–Fluoroalkoxide Tungsten(VI) Complexes for Growth of WO<sub><i>x</i></sub> Thin Films by Aerosol-Assisted Chemical Vapor Deposition
作者:Richard O. Bonsu、Hankook Kim、Christopher O’Donohue、Roman Y. Korotkov、Khalil A. Abboud、Timothy J. Anderson、Lisa McElwee-White
DOI:10.1021/acs.inorgchem.5b01124
日期:2015.8.3
The soluble bis(fluoroalkOxide) dioxo tungsten(VI) complexes WO2(OR)(2)(DME) [1,R = C(CF3)(2)CH3; 2, R = C(CF3)(3)] have been synthesized by alkoxide-chloride metathesis and evaluated as precursors for aerosol-assisted chemical vapor deposition (AACVD) of WOx. The H-1 NMR and F-19 NMR spectra of 1 and 2 are consi$tent with an equilibrium between the dimethoxyetharie (DME) complexes 1 and 2 and the solvato complexes WO2(OR)(2)(CD3CN)(2) [1b, R = C(CF3)(2)CH3; 2b, R = C(CF3)(3)] in acetonitrile-d(3) solution. Studies of the fragmentation of 1 and 2 by mass spectrometry and therrnolysis resulted in observation of DME and the corresponding alcohols, with hexafluoroisobutylene also generated from 1. DFT calculations on possible decomposition mechanisms for 1 located pathways for hydrogen abstraction by a terminal oxo to form hexafluoroisobutylene, followed by dimetization of the resulting terminal hydroxide complex and dissociation of the alcohol. AACVD using 1 occurred between 100 and 550 degrees C and produced both substoichiometric amorphous WOx and a polycrystalline W18O49 monoclinic phase, which exhibits 1-D preferred growth in the [010] direction. The work fuhction (4.9-5.6 eV), mean optital transmittance (39.1-91.1%), conductivity (0.4-2.3 S/cm), and surface roughness (3.4-7.9 nm) of the WOx films are suitable for charge injection layers in organic electronics.