Bimetallic isopropoxides M[Al(OC3Hi7)4]3 (M†=†Pr, Nd)-catalyzed reduction of 2-octanone and benzophenone

Bimetallic alkoxides of praseodymium and neodymium with aluminum, viz., M[Al(OC3Hi7)4]3, where M = Pr(III)/Nd(III), have been used as catalysts in Meerwein-Ponndorf-Verley (MPV) reduction of 2-octanone and benzophenone in isopropanol to give their corresponding secondary alcohols. The reduction of ketones is investigated by following the absorption spectra involving 4f-4f transitions. During the MPV reduction the oscillator strengths (P) and the Judd-Ofelt intensity (Tλ, λ=2,4,6) parameters corresponding to each 4f-4f band (H43→D21, H43→P03, H43→P13, and H43→P23 in praseodymium, and I9/24→F3/24, I9/24→F5/24, I9/24→F7/24, I9/24→G5/24, and I9/24→G7/24 in neodymium alkoxides) at different time intervals have also been calculated and used in the determination of rates. Rates were calculated in terms of complexation of ketone and isopropanol with M[Al(OC3Hi7)4]3 during the MPV reaction, from the changes in both absorbance and oscillator strength with time, and were found to be comparable, verifying the Judd-Ofelt theory. The stronger oxyphilicity of Pr(III) and Nd(III) in M[Al(OC3Hi7)4]3 than of their analogue Al(III) in Al(OC3Hi7)3 made the bimetallic alkoxides better catalyst in MPV reduction of ketones.