Studies on Molybdena- and Tungstenacyclobutadiene Complexes Supported by Fluoroalkoxy Ligands as Intermediates of Alkyne Metathesis
Studies on Molybdena- and Tungstenacyclobutadiene Complexes Supported by Fluoroalkoxy Ligands as Intermediates of Alkyne Metathesis
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DOI：
10.1021/acs.organomet.9b00068
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发表时间：
2019-04-08
期刊：
影响因子：
2.8
通讯作者：
Tamm, Matthias
中科院分区：
文献类型：
--
作者：
Ehrhorn, Henrike;Bockfeld, Dirk;Tamm, Matthias
制备了钼和钨 2,4,6-三甲基苄基[MesC M{OC(CF3)(2)Ph}(3)] (12a, M = Mo; 12b, M = W)，并在结构上表征为与已知的 [MesC M{OC(CF3)(2)Me}(3)] (MoF6, M = Mo; WF6, M = W) 相关的配合物。用 3-己炔处理 12a 产生丙炔络合物 [EtC Mo{OC(CF3)(2)Ph}(3)] (13)，而钨同源物 12b 通过与 3-己炔、1-苯基-1-丙炔和 2,4-己二炔反应形成可分离的金属环丁二烯 (MCBD) 物质 14-16，这可以与钨配合物的亲电性越高。此外，在低温下从高活性MoF6催化剂与3-己炔的反应中分离出不稳定的MCBD [(C3Et3)Mo{OC(CF3)(2)Me}(3)] (17)，并可以通过X射线衍射分析进行表征。在室温下，相同的反应得到[EtC Mo{OC(CF3)(2)Me}(3)] (18)，并且通过变温NMR光谱进一步研究了与3-己炔形成17的平衡反应，这使得可以确定MCBD 17形成的Delta H度和Delta S度。实验热力学数据用于设定DFT计算的基准。此外，由[MesC Mo{OC(CF3)(3)}(3)] (MoF9)和苯乙炔制备的脱杷金属环丁二烯配合物(DPMCBD) [C-3(Mes)(Ph)}Mo{OC(CF3)(3)}(2)] (19)被分离和结构表征为末端炔复分解的分解产物，并用于苯乙炔的聚合。
The molybdenum and tungsten 2,4,6-trimethylbenzylidynes [MesC M{OC(CF3)(2)Ph}(3)] (12a, M = Mo; 12b, M = W) were prepared and structurally characterized as related complexes to already known [MesC M{OC(CF3)(2)Me}(3)] (MoF6, M = Mo; WF6, M = W). While treatment of 12a with 3-hexyne yielded the propylidyne complex [EtC Mo{OC(CF3)(2)Ph}(3)] (13), the tungsten congener 12b formed isolable metallacyclobutadiene (MCBD) species 14-16 by reaction with 3-hexyne, 1-phenyl-1-propyne, and 2,4-hexadiyne, which can be correlated with the higher electrophilicity of the tungsten complex. Furthermore, the labile MCBD [(C3Et3 )Mo{OC(CF3)(2)Me}(3)] (17) was isolated at low temperature from the reaction of the highly active MoF6 catalyst with 3-hexyne and could be characterized by X-ray diffraction analysis. At room temperature, the same reaction afforded [EtC Mo{OC(CF3)(2)Me}(3)] (18), and the equilibrium reaction with 3-hexyne to form 17 was additionally studied by variable temperature NMR spectroscopy, which allowed determining Delta H degrees and Delta S degrees for the formation of MCBD 17. The experimental thermodynamic data were used to set the benchmark for DFT calculations. Moreover, the deprotiometallacyclobutadiene complex (DPMCBD) [C-3(Mes)(Ph)}Mo{OC(CF3)(3)}(2)] (19), prepared from [MesC Mo{OC(CF3)(3)}(3)] (MoF9) and phenylacetylene, was isolated and structurally characterized as a decomposition product of terminal alkyne metathesis and employed in the polymerization of phenylacetylenes.