Isomers of Cyclometalated Macrocycles Constructed through Olefinic C–H Activation

A new series of dinuclear complexes [(Cp*M)2{(2-pyridyl)-CC-(2-pyridyl)}­Cl2] (M = Rh (1a), Ir (1b)) and tetranuclear metallamacrocycles [{(Cp*M)2{(2-pyridyl)-CC-(2-pyridyl)}­(pyrazine)}2]­(OTf)4 (M = Rh (2a), Ir (2b)), [{(Cp*M)2{(2-pyridyl)-CC-(2-pyridyl)}­(bpy)}2]­(OTf)4 (M = Rh (3a), Ir (3b); bpy = 4,4′-bipyridine), and [{(Cp*M)2{(2-pyridyl)-CC-(2-pyridyl)}­(bpe)}2]­(OTf)4 (M = Rh (4a), Ir (4b); 4,4′-bpe = trans-1,2-bis­(4-pyridyl)­ethylene) were constructed stepwise through double-site C–H activation on the olefinic CC bond of 1,2-bis­(2-pyridyl)­ethylene. Isomers were observed in both the dinuclear species and tetranuclear macrocyclic complexes and were confirmed by single-crystal X-ray diffraction. The molecular structures of 1a–c, (R,R)-(S,S)-3b, (R,R)-(S,S)-4a, (R,R)-(R,R)-/(S,S)-(S,S)-4a, and (R,R)-(S,S)-4b were characterized by single-crystal X-ray crystallography. All complexes were fully characterized by 1H NMR spectroscopy, ESI-MS, and elemental analysis.本研究通过对1,2-二(2-吡啶基)乙烯的烯烃C=C键实施双位点C-H活化，逐步构建了一系列新型双核配合物与四核金属大环。其中双核配合物为[(五甲基环戊二烯基(Cp*)M)₂{(2-吡啶基)-C=C-(2-吡啶基)}Cl₂]（M = 铑(Rh，1a)、铱(Ir，1b)）；四核金属大环包括[{(五甲基环戊二烯基(Cp*)M)₂{(2-吡啶基)-C=C-(2-吡啶基)}(吡嗪)}₂](三氟甲磺酸盐(OTf))₄（M = 铑(Rh，2a)、铱(Ir，2b)）、[{(五甲基环戊二烯基(Cp*)M)₂{(2-吡啶基)-C=C-(2-吡啶基)}(bpy)}₂](三氟甲磺酸盐(OTf))₄（M = 铑(Rh，3a)、铱(Ir，3b)；bpy = 4,4'-联吡啶）以及[{(五甲基环戊二烯基(Cp*)M)₂{(2-吡啶基)-C=C-(2-吡啶基)}(bpe)}₂](三氟甲磺酸盐(OTf))₄（M = 铑(Rh，4a)、铱(Ir，4b)；4,4'-bpe = 反式-1,2-二(4-吡啶基)乙烯）。双核物种与四核大环配合物中均存在异构体，相关异构体经单晶X射线衍射得到确证。通过单晶X射线晶体学对1a~1c、(R,R)-(S,S)-3b、(R,R)-(S,S)-4a、(R,R)-(R,R)-/(S,S)-(S,S)-4a以及(R,R)-(S,S)-4b的分子结构完成了表征。所有配合物均通过¹H核磁共振波谱、电喷雾电离质谱(ESI-MS)及元素分析实现了全面表征。