Flat and Efficient HCNN and CNN Pincer Ruthenium Catalysts for Carbonyl Compound Reduction

摘要

The bidentate HCNN dicarbonyl ruthenium complexes trans,cis-[RuCl2(HCNN)(CO)(2)] (1-3) and trans,cis-[RuCl2(ampy)(CO)(2)] (1a) were prepared by reaction of [RuCl2(CO)(2)](n) with 1-[6-(4'-methylphenyl)pyridin-2-yl]methanamine, benzo[h]quinoline (HCNN), and 2-(aminomethyl)pyridine (ampy) ligands. Alternatively, the derivatives 13 were obtained from the reaction of RuCl3 hydrate with HCO2H and HCNN. The pincer CNN cis-[RuCl(CNN)(CO)(2)] (4) was isolated from 1 by reaction with NEt3. The monocarbonyl complexes trans-[RuCl2(HCNN)(PPh3)(CO)] (5-7) were synthesized from [RuCl2(dmf)(PPh3)2(CO)] and HCNN ligands, while the diacetate trans-[Ru(OAc)(2)(HCNN)(PPh3)(CO)] (8) was obtained from [Ru(OAc)(2)(PPh3)(2)(CO)]. Carbonylation of cis-[RuCl(CNN)(PPh3)(2)] with CO afforded the pincer derivatives [RuCl(CNN)(PPh3)(CO)] (9-11). Treatment of 9 with Na[BArf](4) and PPh3 gave the cationic complex trans-[Ru(CNN)(PPh3)(2)(CO)][BAr4f] (12). The dicarbonyl derivatives 1-4, in the presence of PPh3 or PCy3, and the monocarbonyl complexes 5-12 catalyzed the transfer hydrogenation (TH) of acetophenone (a) in 2-propanol at reflux (S/C = 1000100000 and TOF up to 100000 h(-1)). Compounds 13, with PCy3, and 6 and 8-10 were proven to catalyze the TH of carbonyl compounds, including alpha,beta-unsaturated aldehydes and bulky ketones (S/C and TOF up to 10000 and 100000 h(-1), respectively). The derivatives 1-3 with PCy3 and 5 and 6 catalyzed the hydrogenation (HY) of a (H-2, 30 bar) at 70 degrees C (S/C = 2000-10000). Complex 5 was active in the HY of diaryl ketones and aryl methyl ketones, leading to complete conversion at S/C = 10000.