Insertion of Isonitriles into the M–C Bonds of Group 4 Dialkyl Complexes
Insertion of Isonitriles into the M–C Bonds of Group 4 Dialkyl Complexes
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将异腈插入第 4 族二烷基配合物的 M−C 键中
DOI：
10.1021/jacs.8b05377
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发表时间：
2018
影响因子：
15
通讯作者：
Rauch, Michael
中科院分区：
文献类型：
--
作者：
Chen, Jiawei;Yassin, Nadine;Gunasekara, Thilina;Norton, Jack R.;Rauch, Michael
合成了具有约束几何(CG)配体的4族金属的2，3-二甲基丁二烯配合物，发现它们以σ-2，π键呈仰卧取向。将cgTi(2，3-二甲基丁二烯)(1-Ti)与丁二烯反应生成钛氮杂环丙烷(3)，并通过二烯与异腈的形式[4+1]加成生成配位环戊烯亚胺。相反，cgZr(2，3-二甲基丁二烯)(1-Zr)或cgHf(2，3-二甲基丁二烯)(1-HF)与2当量的丁NC或XyNC的反应以更复杂的方式进行，生成不对称的2，5-二氮杂茂环戊烷衍生物(4，6-Zr和6-HF)或对称的2，5-二氮杂茂金属环戊烯配合物(7-Zran7-HF)。不对称的产物含有配位的环丙烷；相互作用的强度是通过配位的C-C键的1JCC还原来衡量的。对相关的cgM(Me)2(M=Ti和Hf)络合物进行了详细的机理分析。第一次插入的速度太快，无法监测，但可以完全转化为烷基亚氨基酰基中间体。第二异腈(RNC)可以通过还原消除和配位/插入两种不同机制中的任何一种与该中间体反应。在第一种反应机理(Ti)中，C-C偶联反应速率决定，生成钛氮杂环丙烷，然后是异腈的快速配位。在第二种机制(HF)中，配位是缓慢的步骤，插入形成双(亚氨基酰基)HF络合物是快速的。
The 2,3-dimethylbutadiene complexes of Group 4 metals with constrained geometry (cg) ligands have been prepared and found to adopt a supine orientation with σ2,π bonding. Treatment of cgTi(2,3-dimethylbutadiene) (1-Ti) withtBuNC leads to the formation of a titana-aziridine (3) with a coordinated cyclopentenimine that arises from the formal [4+1] addition of the diene to the isonitrile. In contrast, the reactions of cgZr(2,3-dimethylbutadiene) (1-Zr) or cgHf(2,3-dimethylbutadiene) (1-Hf) with 2 equiv oftBuNC or XyNC proceeded in a more sophisticated manner to yield unsymmetrical 2,5-diazametallacyclopentane derivatives (4,6-Zr, and6-Hf) or symmetrical 2,5-diazametallacyclopentene complexes (7-Zrand7-Hf). The unsymmetrical products contain coordinated cyclopropanes; the strength of the interaction is measured by the reduction in the1JCCof the C–C bond that is coordinated. A detailed mechanistic analysis has been possible with the relatedcgM(Me)2(M = Ti and Hf) complexes. The first insertion is too fast to monitor, but allows complete conversion to an alkyl iminoacyl intermediate. The second isonitrile (RNC) may react with that intermediate by either of two different mechanisms, reductive elimination and coordination/insertion. In the first mechanism (Ti), rate-determining C–C coupling gives a titana-aziridine, followed by fast coordination of the isonitrile. In the second mechanism (Hf), coordination is the slow step; insertion to form a bis(iminoacyl) Hf complex is rapid.