화학공학소재연구정보센터
Journal of Catalysis, Vol.337, 157-166, 2016
Decoding catalytic activity of platinum carbene hydrosilylation catalysts
A series of complexes of the formula [Pt(dvtms)(ImPy-R)] (dvtms = 1,1,3,3-tetramethy1-1,3-divinyldisiloxane, ImPy-R = 2-R-imidazo[1,5-a]pyridine-3-ylidene; R = 4-cyanophenyl (4a), 4-trifluoromethyiphenyl (4b), phenyl (4c), 4-methoxyphenyl (4d), mesityl (4e), pentafluorophenyl (4f), tert-butyl (4g)) are presented. These compounds are synthesized from Karstedt's catalyst [Pt-2(dvtms)(3)] and the respective imidazo[1,5-a]pyridinium salts using (BuOK)-Bu-t as base. 4a-g were characterized (H-1, C-13, F-19, (195)pt NMR, EA, IR, UV-Vis) and investigated by cyclic voltammetry. The compounds are efficient and selective catalysts in the model hydrosilylation reaction of oct-1-ene with HSi3O2Me7. The combination of spectroscopic and theoretical studies on the B3LYP/6-31G** level of theory reveals a distinct correlation of HOMO energy levels EHomo, oxidation potential E-Ox and catalytic activity (TOF). The impact of the substitution pattern introduced at the ImPy-R ligand can be interpreted based on electronics (Hammet correlation) and sterics of the residues R. (C) 2016 Elsevier Inc. All rights reserved.