Schuman Ashley J, Robey Sarah F T, Judkins Eileen C, Zeller Matthias, Ren Tong
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
Dalton Trans. 2021 Apr 14;50(14):4936-4943. doi: 10.1039/d1dt00707f. Epub 2021 Mar 25.
Described herein is the synthesis and characterization of macrocyclic Cr mono-alkynyl complexes. By using the meso-form of the tetraazamacrocycle HMC (HMC = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane), trans-[Cr(HMC)(CPh)Cl]OTf (1a), trans-[Cr(HMC)(CNp)Cl]OTf (2a), trans-[Cr(HMC)(CCHBu)Cl]OTf (3a), and trans-[Cr(HMC)(C(3,5-ClCH))Cl]OTf (4a) complexes have been realized. These complexes were synthesized in high yield through the reaction of trans-[Cr(meso-HMC)(CAr)]OTf (1b-4b) with stoichiometric amounts of methanolic HCl. Single crystal X-ray diffraction showed that the trans-stereochemistry and pseudo-octahedral geometry is retained in the desired mono-alkynyl complexes. The absorption spectra of complexes 1a-4a display d-d bands with distinct vibronic progressions that are slightly red shifted from trans-[Cr(HMC)(CAr)] with approximately halved molar extinction coefficients. Time-delayed measurements of the emission spectra for complexes 1a-4a at 77 K revealed phosphorescence with lifetimes ranging between 343 μs (4a) and 397 μs (1a). The phosphorescence spectra of 1a-4a also exhibit more structuring than the bis-alkynyl complexes due to a strengthened vibronic coupling between the Cr metal center and alkynyl ligands.
本文描述了大环铬单炔基配合物的合成与表征。通过使用四氮大环HMC（HMC = 5,5,7,12,12,14 - 六甲基 - 1,4,8,11 - 四氮杂环十四烷）的内消旋形式，实现了反式 - [Cr(HMC)(CPh)Cl]OTf（1a）、反式 - [Cr(HMC)(CNp)Cl]OTf（2a）、反式 - [Cr(HMC)(CCHBu)Cl]OTf（3a）和反式 - [Cr(HMC)(C(3,5 - ClCH))Cl]OTf（4a）配合物的合成。这些配合物通过反式 - [Cr(内消旋 - HMC)(CAr)]OTf（1b - 4b）与化学计量的甲醇盐酸反应以高产率合成。单晶X射线衍射表明，在所需的单炔基配合物中保留了反式立体化学和伪八面体几何结构。配合物1a - 4a的吸收光谱显示出具有明显振动进展的d - d带，与反式 - [Cr(HMC)(CAr)]相比略有红移，摩尔消光系数约减半。在77 K下对配合物1a - 4a的发射光谱进行时间延迟测量，结果显示磷光寿命在343 μs（4a）至397 μs（1a）之间。由于Cr金属中心与炔基配体之间的振动耦合增强，1a - 4a的磷光光谱也比双炔基配合物表现出更多的结构。
