Synthesis and Characterization of Ethylbis(2-pyridylethyl)amineruthenium Complexes and Two Different Types of C–H Bond Cleavage at an Ethylene Arm

Ruthenium complexes bearing ethylbis(2-pyridylethyl)amine (ebpea), which has flexible −C2H4– arms between the amine and the pyridyl groups and coordinates to a metal center in facial and meridional modes, have been synthesized and characterized. Three trichloro complexes, fac-[RuIIICl3(ebpea)] (fac-[1]), mer-[RuIIICl3(ebpea)] (mer-[1]), and mer-[RuIICl3{η2-N(C2H5)(C2H4py)CH–CH2py}] (mer-[2]), were synthesized using the Ru blue solution. Formation of mer-[2] proceeded via a C–H activation of the CH2 group next to the amine nitrogen atom of the ethylene arm. Reduction reactions of fac- and mer-[1] afforded a triacetonitrile complex mer-[RuII(CH3CN)3(ebpea)](PF6)2 (mer-[3](PF6)2). Five nitrosyl complexes fac-[RuX2(NO)(ebpea)]PF6 (X = Cl for fac-[4]PF6; X = ONO2 for fac-[5]PF6) and mer-[RuXY(NO)(ebpea)]PF6 (X = Cl, Y = Cl for mer-[4]PF6; X = Cl, Y = CH3O for mer-[6]PF6; X = Cl, Y = OH for mer-[7]PF6) were synthesized and characterized by X-ray crystallography. A reaction of mer-[2] in H2O–C2H5OH at room temperature afforded mer-[1]. Oxidation of C2H5OH in H2O–C2H5OH and i-C3H7OH in H2O–i-C3H7OH to acetaldehyde and acetone by mer-[2] under stirring at room temperature occurred with formation of mer-[1]. Alternative C–H activation of the CH2 group occurred next to the pyridyl group, and formation of a C–N bond between the CH moiety and the nitrosyl ligand afforded a nitroso complex [RuII(N3)2{N(O)CH(py)CH2N(C2H5)C2H4py}] ([8]) in reactions of nitrosyl complexes with sodium azide in methanol, and reaction of [8] with hydrochloric acid afforded a corresponding chloronitroso complex [RuIICl2{N(O)CH(py)CH2N(C2H5)C2H4py}] ([9]).

携带乙基双(2-吡啶乙基)胺（ethylbis(2-pyridylethyl)amine, ebpea）配体的钌配合物——该配体在胺基与吡啶基之间带有柔性亚乙基（−C2H4–）臂，可与金属中心以面式（facial）和经式（meridional）两种模式配位——已被成功合成并完成表征。采用钌蓝溶液合成了三种三氯配合物：fac-[RuIIICl3(ebpea)]（记为fac-[1]）、mer-[RuIIICl3(ebpea)]（记为mer-[1]），以及mer-[RuIICl3{η2-N(C2H5)(C2H4py)CH–CH2py}]（记为mer-[2]）。其中mer-[2]的生成经由亚乙基臂中紧邻胺氮原子的亚甲基（CH2）发生碳氢键活化过程完成。对fac-[1]与mer-[1]实施还原反应，得到三乙腈配合物mer-[RuII(CH3CN)3(ebpea)](PF6)2（记为mer-[3](PF6)2）。成功合成五种亚硝酰配合物：fac-[RuX2(NO)(ebpea)]PF6（X=Cl时为fac-[4]PF6；X=ONO2时为fac-[5]PF6），以及mer-[RuXY(NO)(ebpea)]PF6（X=Cl、Y=Cl时为mer-[4]PF6；X=Cl、Y=CH3O时为mer-[6]PF6；X=Cl、Y=OH时为mer-[7]PF6），并借助X射线晶体衍射完成了结构表征。将mer-[2]置于水-乙醇混合溶剂中室温反应，可得到mer-[1]。在室温搅拌条件下，mer-[2]可将水-乙醇混合溶剂中的乙醇、水-异丙醇混合溶剂中的异丙醇分别氧化为乙醛与丙酮，自身则转化为mer-[1]。当吡啶基邻位的亚甲基发生另一类碳氢键活化时，亚硝酰配合物与叠氮化钠在甲醇中反应，可使CH片段与亚硝酰配体间形成C-N键，得到亚硝酰配合物[RuII(N3)2{N(O)CH(py)CH2N(C2H5)C2H4py}]（记为[8]）；将[8]与盐酸反应，可得到对应的氯代亚硝酰配合物[RuIICl2{N(O)CH(py)CH2N(C2H5)C2H4py}]（记为[9]）。