Blue-Green Luminescent Rhenium(I) Tricarbonyl Complexes with Pyridine-Functionalized N-Heterocyclic Carbene Ligands

Five rhenium­(I) tricarbonyl chloride complexes with pyridine-functionalized
N-heterocyclic carbenes, Re­(CO)3(L)Cl (L = 3-methyl-1-(2-pyridyl)­imidazol-2-ylidene
(1), 3-methyl-1-(2-picolyl)­imidazol-2-ylidene (2), 3-methyl-1-(2-pyridyl)­benzimidazolin-2-ylidene (3), 3-methyl-1-(2-picoyl)­benzimidazolin-2-ylidene (4), 1-methyl-4-(2-pyridyl)-1,2,4-triazoline-5-ylidene (5)), have been synthesized by silver carbene transmetalation and characterized
by elemental analysis, 1H NMR, 13C NMR, and
IR spectra. The molecular structures of 3–5 have been determined by single-crystal X-ray diffraction.
The electrochemical and photophysical properties of complexes 1, 3, and 5 have been studied. In
both degassed CH2Cl2 solution and the solid
state at room temperature or 77 K, the emission wavelengths (465–511
nm) of complexes 1, 3, and 5 lie in the blue-green region, which are rare in contrast to the
reported rhenium­(I) tricarbonyl complexes. The photoluminescence lifetime
decays of Re­(I) complexes 1, 3, and 5 were measured, and the quantum yields were calculated by
using the standard sample ([Ru­(bpy)3]2+(Cl–)2 in degassed acetonitrile solution; Φstd = 0.094).

五种铼(I)三羰基氯化物复合物，具有吡啶官能化的N-杂环卡宾（Re(CO)3(L)Cl，其中L分别为3-甲基-1-(2-吡啶基)咪唑-2-亚胺基(1)、3-甲基-1-(2-吡啶基)咪唑-2-亚胺基(2)、3-甲基-1-(2-吡啶基)苯并咪唑-2-亚胺基(3)、3-甲基-1-(2-吡啶基)苯并咪唑-2-亚胺基(4)和1-甲基-4-(2-吡啶基)-1,2,4-三唑-5-亚胺基(5)），通过银卡宾转金属化方法合成，并通过元素分析、1H NMR、13C NMR和红外光谱进行表征。复合物3-5的分子结构通过单晶X射线衍射确定。复合物1、3和5的电化学和光物理性质已被研究。在室温和77 K下，无气体的CH2Cl2溶液和固态中，复合物1、3和5的发射波长（465-511 nm）位于蓝绿色区域，与已报道的铼(I)三羰基复合物相比较为罕见。通过使用标准样品([Ru(bpy)3]2+(Cl-)2在无气体的乙腈溶液中；Φstd = 0.094)测量了Re(I)复合物1、3和5的磷光寿命，并计算了量子产率。