Reactivity of Scorpionate-Anchored Yttrium Alkyl Complex toward Organic Nitriles
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The mixed TpMe2/Cp-supported yttrium monoalkyl (TpMe2)CpYCH2Ph(THF) (1) reacted with 1 equiv of PhCN in THF at room temperature to afford the imine–enamine tautomer (TpMe2)CpY(N(H)C(Ph)CHPh)(THF) (2) and the insertion product (TpMe2)CpY(NC(CH2Ph)Ph)(THF) (3), in 61% and 12% isolated yields, respectively. 2 further reacted with PhCN in toluene at 120 °C to give the N–H bond addition product (TpMe2)CpY(N(H)C(Ph)NC(Ph)CHPh) (4). Treatment of 1 with 1 equiv of anthranilonitrile produced the dimer [(TpMe2)CpY(μ-NHC6H4CN)]2 (5). The monomer product (TpMe2)CpY(NHC6H4CN)(HMPA) (6) can be obtained through the coordination of HMPA (hexamethylphosphoric triamide). The reaction of 5 with 1 in THF at room temperature gave the cyano group insertion product [(TpMe2)CpY(THF)]2(μ-NHC6H4C(CH2Ph)N) (7). However, this reaction under the heating conditions gave an unexpected rearrangement product, (TpMe2)CpY(THF)(η2-NHC6H4C(CH2Ph)NH) (8). 5 further reacted with o-aminobenzonitrile at 120 °C to afford the nucleophilic addition/cyclization product TpMe2Y[κ3-(4-NH(C8N2H4)(2-NHC6H4)](HMPA) (9), accompanied with the elimination of the Cp ring. These results indicated that the yttrium alkyl complex exhibits high activity toward organic nitriles and reveals some unusual transformations during the insertion process. All these new complexes were characterized by elemental analysis and spectroscopic methods, and their solid-state structures were also confirmed by single-crystal X-ray diffraction analysis.
以TpMe2与环戊二烯基（Cyclopentadienyl, Cp）共同支撑的一烷基钇配合物(TpMe2)CpYCH2Ph(THF) (1)，于室温下在四氢呋喃（Tetrahydrofuran, THF）中与1当量苯甲腈（Benzonitrile, PhCN）反应，分别以61%和12%的分离产率得到亚胺-烯胺互变异构体(TpMe2)CpY(N(H)C(Ph)=CHPh)(THF) (2)与插入产物(TpMe2)CpY(N=C(CH2Ph)Ph)(THF) (3)。配合物2进一步于甲苯中在120 ℃条件下与PhCN反应，得到N-H键加成产物(TpMe2)CpY(N(H)C(Ph)NC(Ph)=CHPh) (4)。将配合物1与1当量邻氨基苯甲腈（Anthranilonitrile）反应，得到二聚体[(TpMe2)CpY(μ-NHC6H4CN)]2 (5)。通过六甲基磷酰胺（Hexamethylphosphoric triamide, HMPA）配位，可分离得到单体产物(TpMe2)CpY(NHC6H4CN)(HMPA) (6)。配合物5与1在室温下的THF中反应，得到氰基插入产物[(TpMe2)CpY(THF)]2(μ-NHC6H4C(CH2Ph)=N) (7)。但该反应在加热条件下则得到意外的重排产物(TpMe2)CpY(THF)(η2-NHC6H4C(CH2Ph)=NH) (8)。配合物5在120 ℃下进一步与邻氨基苯甲腈反应，得到亲核加成/环化产物TpMe2Y[κ3-(4-NH=(C8N2H4)(2-NHC6H4)](HMPA) (9)，同时伴随Cp环的消除过程。上述结果表明，该烷基钇配合物对有机腈类底物展现出较高的反应活性，并揭示了插入过程中若干非常规的转化路径。所有新合成的配合物均通过元素分析与光谱分析法进行了表征，其固态分子结构亦经单晶X射线衍射分析得以确认。
