화학공학소재연구정보센터
Inorganic Chemistry, Vol.51, No.19, 10408-10416, 2012
Synthesis of Backbone P-Functionalized Imidazol-2-ylidene Complexes: En Route to Novel Functional Ionic Liquids
1-Alkyl-3-methyl-4-diphenylphosphoryl-imidazolium hydrogensulfate (4a,b) (a: R-1 = R-2 = Me; b: R-1 = Pr-i, R-2 = Me) and 1-alkyl-3-methyl-4,5-bis(diphenylphosphoryl)imidazolium hydrogensulfate (6a,c) (c: R-1 = '' Bu, R-2 = Me) were obtained selectively and in good yields by oxidative desulfurization of 1-alkyl-3-methyl-4-diphenylphosphino-imidazole-2-thiones (2a,b) and 1-n-butyl-3-methyl-4,5-bis(diphenylphosphoryl)imidazole-2-thione (3c) or 1,3-dimethyl-4-diphenylthiophosphoryl-5-diphenylphosphino-imidazole-2-thione (5a), respectively, with hydrogen peroxide. Synthesis of phosphoryl functionalized imidazol-2-ylidene complexes of group VI metal pentacarbonyls (7a-9a) and (10b-12b) and bis(phosphoryl) functionalized imidazol-2-ylidene complexes of group VI metal pentacarbonyls (13c-15c) and (16a) with low steric demand (methyl, isopropyl, n-butyl) at both N-centers was achieved through deprotonation of imidazolium salts (4a,b) and (6a,c), respectively,-having HSO4- as a counterion-with potassium tert-butoxide followed by rapid addition of metal pentacarbonyl acetonitrile complexes [M(CO)(5)(CH3CN)] (M = Cr, Mo, W). The products were unambiguously characterized by elemental analyses, spectroscopic and spectrometric methods, and in addition, by single-crystal X-ray structure studies in the cases of 4b, 8a, 15c, and 16a; the latter two reveal imidazole ring bond distance alternation in contrast to 8a.