Synthesis and Crystal Structure of 1-Methyl-3-(2-pyridyl)imidazolium Hexafluorophosphate

Compound 1-Methyl-3-(2-pyridyl)imidazolium hexafluorophosphate was crystallized in monoclinic system with space group and unit cell parameters , , , , and？？ . The obtained solid state structure of 1-Methyl-3-(2-pyridyl)imidazolium hexafluorophosphate shows CH？F type weak interactions and was analyzed. 1. Introduction The chemistry of N-heterocyclic carbene (NHC) has become emerged field after the crystal structure of free 1,3-diadamantyl imidazol-2-ylidene was first reported in 1991 by Arduengo III et al. [1–3]. The chemical durability of NHC encouraged the chemist to study their reactivity with inorganic and organic compounds. The synthesis of NHC normally had been done by removal of C-2 proton of imidazolium salt with a suitable base. Many examples of imidazolium salts were synthesized and their corresponding NHC and NHC-metal compounds were studied [4, 5]. The interesting criteria of the imidazole are that, by tuning the substitution on nitrogen center at the imidazole ring, different types of functionalized imidazolium salts have been synthesized [6–9]. Herein, the modified synthesis of 1-Methyl-3-(2-pyridyl)imidazolium hexafluorophosphate (1) and its crystal structure have been discussed. 2. Materials and Methods A mixture 2-chloropyridine (1.35？g, 10？mmole) and 1-methylimidazole (0.821？g, 10？mmole) were heated at 150°C for 20 hours. To this mixture saturated aqueous solution of KPF6 was added, while the mixture was hot and it results in the rapid precipitation of white color substance. The obtained white color precipitate was filtrated off and dried in vacuum. The colorless block type crystals of (MeIMPy)(PF6) were obtained after one week from methanolic solution. Yield (based on 1-methylimidazole): 1.05？g, 34%. Anal. Calcd. for C9H10N3F3P (305.17): C, 35.26; H, 3.42; N, 13.48. Found: C, 35.42; H, 3.30; N, 13.77. 1H NMR (400？MHz, CD3OD, 22°C,δ): 3.93 (s, 3H), 7.61 (m, 2H), 7.76 (d, 1H), 8.07 (m, 1H), 8.12 (m, 1H), 8.48 (m, 1H), 9.26 (s, 1H). 2-Chloropyridine (99.0%), 1-methylimidazole (99.0%), and KPF6 (98.0%) were purchased from Sigma-Aldrich and used as received. 1H NMR spectra were obtained on a JEOL-JNM LAMBDA 400 model spectrometer operating at 400？MHz. The spectra were recorded in CD3OD solution, and the chemical shifts were referenced with respect to TMS. Crystal was coated with light hydrocarbon oil and mounted in the 100？K dinitrogen stream of Bruker SMART APEX CCD diffractometer equipped with CRYO Industries low-temperature apparatus and intensity data were collected using graphite monochromated Mo Kα radiation ( ). The data integration