1. The “Helmet Phthalocyanines”: Synthetic and Catalytic Studies on a New Class of Chiral Phthalocyaninato-Metal Complexes
Robert W. McGaff, Chemistry Department, University of Wisconsin-La Crosse
The central goal of our PRF-supported research is the discovery of enantioselective oxidation catalysts from among two sub-classes of modified metallophthalocyaninato complexes. One sub-class consists of the so-called “helmet” metallophthalocyanines of general formula L(diiPc)M, where diiPc is the 14,28-[1,3-diiminoisoindolinato]phthalocyaninato ligand, L is a labile monodentate ligand, and M represents Fe(III) or Co(III).  Over the course of the past grant year, we have chosen to concentrate our efforts on the catalytic (as opposed to enantiomer separation) aspects of the project, with some exciting and promising results. More specifically, we have focused primarily on the catalytic oxidation of cyclohexane and cyclooctane employing the iron(III) “helmet” complex. Specifically, we have seen that:
(1) L(diiPc)Fe catalyzes the oxidation of cyclohexane by hydrogen peroxide to give cyclohexanol with a turnover number (TON) = and cyclohexanone with TON = To our knowledge this represents the best performance of any non-heme iron-based cyclohexane oxidation catalyst to date in terms of TON and selectivity for the alcohol.
The same iron complex catalyzes the oxidation of cyclooctane under analogous conditions with TON = for cyclooctanol and TON = 5.8 for cyclooctanone. To our knowledge this far surpasses the best performance of any reported non-heme iron-based cyclooctane oxidation catalyst to date in terms of selectivity and TON for the alcohol.
L(diiPc)Fe also catalyzes the oxidation of indan to 1-indanol with TON = 10.1, significant because 1-indanol is chiral and thus represents a target for asymmetric catalysis.
We are currently seeking to separate and isolate enantiopure or enriched samples of L(diiPc)Fe in sufficient quantity to allow for investigation of its enantioselective catalytic properties in similar oxidations.