Synthesis of Alkyl and Alkylidene Complexes of Tungsten Bearing Imido and Redox-Active α-Diimine or o-Iminoquinone Ligands and Their Application as Catalysts for Ring-Opening Metathesis Polymerization of Norbornene
Synthesis of Alkyl and Alkylidene Complexes of Tungsten Bearing Imido and Redox-Active α-Diimine or o-Iminoquinone Ligands and Their Application as Catalysts for Ring-Opening Metathesis Polymerization of Norbornene
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含钨亚氨基和氧化还原活性α-二胺或邻亚氨基醌配体的烷基和亚烷基配合物的合成及其作为降冰片烯开环复分解聚合催化剂的应用
DOI：
10.1021/om501010n
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发表时间：
2015
期刊：
影响因子：
2.8
通讯作者：
Kazushi Mashima
中科院分区：
文献类型：
--
作者：
Hiromasa Tanahashi;Hayato Tsurugi;Kazushi Mashima
本文报道了一种新的合成含双齿氧化还原活性配体的钨酰亚胺配合物的方法，即用1-甲基-3，6-双（三甲基硅基）-1，4-环己二烯（MBTCD）还原高价钨酰亚胺配合物，而不产生任何金属盐废料。W的反应在α-二亚胺和亚氨基醌等氧化还原活性配体存在下，（NH_4N_6H_3 - 2，6-iPr_2）Cl_4和MBTCD与相应的氧化还原活性配体生成了钨亚胺配合物，（α-二亚胺）W（三氟甲基氯）2（1），[（o-亚氨基醌）W（NO_3N_6H_3 - 2，6-iPr_2）Cl]_2（μ-Cl）_2（3）和（o-亚氨基醌）W（NO_3N_6H_3 - 2，6-iPr_2）Cl_2（THF）（4），沿着有Me_3SiCl和甲苯作为全部副产物。棕色配合物1与[nBu 4 N][Cl]反应得到[nBu 4 N][（α-diimine）W（NO_3-NC_6 H_3 - 2，6-iPr_2）Cl_3]（2）的强绿色单晶。通过光谱分析和X射线衍射研究了α-二亚胺和亚氨基醌配体的多种配位模式。配合物1与1当量的Mg（CH 2 Ph）2·Et 2 O反应生成（α-二亚胺）W（CH 2NH 3 - 2，6-iPr 2）（CH 2 Ph）2（5），5与PMe 2 Ph在80 °C反应生成（α-二亚胺）W（CH 2NH 3 - 2，6-iPr 2）（CH 2 Ph）（PMe 2 Ph）（6）。另一方面，5在CCl 4存在下通过CCl 4的C-Cl键的还原断裂得到不对称的亚苄基配合物（Cl 3C-amido-imino）W（CH 2NC 6 H3 - 2，6-iPr 2）（CH 2CHPh）Cl（7）。分离的亚烷基络合物6和7用作催化剂，用于在甲苯中在80 °C下以1摩尔%的催化剂负载量进行异丙基烯的开环易位聚合。用2当量LiCH_2CMe_2 Ph处理邻-亚氨基醌配合物4，得到二烷基配合物（邻-亚氨基醌）W（CH_2CMe_2 Ph）_2（2，6-iPr_2）（8）。在80 °C下，双烷基络合物5和8作为催化剂，得到了具有较宽多分散性的聚异戊二烯。
We report a new strategy to synthesize tungsten imido complexes bearing bidentate redox-active ligands through reduction of high-valent tungsten imido complexes by 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (abbreviated MBTCD) without forming any metal salt waste. Reaction of W(NC6H3-2,6-iPr2)Cl4and MBTCD in the presence of redox-active ligands, such as α-diimine ando-iminoquinone, produced tungsten imido complexes with the corresponding redox-active ligands, (α-diimine)W(NC6H3-2,6-iPr2)Cl2(1), [(o-iminoquinone)W(NC6H3-2,6-iPr2)Cl]2(μ-Cl)2(3), and (o-iminoquinone)W(NC6H3-2,6-iPr2)Cl2(THF) (4), along with Me3SiCl and toluene as whole byproducts. Reaction of the brown complex1with [nBu4N][Cl] afforded intensely green single crystals of [nBu4N][(α-diimine)W(NC6H3-2,6-iPr2)Cl3] (2). The versatile coordination modes of the α-diimine ando-iminoquinone ligands were clarified by spectroscopic methods and X-ray diffraction studies. Treatment of complex1with 1 equiv of Mg(CH2Ph)2·Et2O resulted in the formation of (α-diimine)W(NC6H3-2,6-iPr2)(CH2Ph)2(5), and thermolysis of5in the presence of PMe2Ph at 80 °C afforded the alkylidene complex (α-diimine)W(NC6H3-2,6-iPr2)(CHPh)(PMe2Ph) (6). On the other hand, thermolysis of5in the presence of CCl4afforded the dissymmetric benzylidene complex (Cl3C-amido-imino)W(NC6H3-2,6-iPr2)(CHPh)Cl (7) via reductive cleavage of the C–Cl bond of CCl4. Isolated alkylidene complexes6and7served as catalysts for ring-opening metathesis polymerization of norbornene with 1 mol% of catalyst loading in toluene at 80 °C. Treatment ofo-iminoquinone complex4with 2 equiv of LiCH2CMe2Ph afforded the dialkyl complex (o-iminoquinone)W(NC6H3-2,6-iPr2)(CH2CMe2Ph)2(8). Dialkyl complexes5and8at 80 °C served as catalysts to give poly(norbornene) with rather broad polydispersity.