A non-heme cationic Fe(iii)-complex intercalated in montmorillonite K-10: synthesis, characterization and catalytic alkane hydroxylation with H2O2 at room temperature

Abstract

A non-heme iron complex cis-[Fe^III(cyclam)Cl₂]Cl (cyclam = 1,4,8,11-tetraazacyclotetradecane) has been intercalated into smectite montmorillonite K-10. The intercalated solid has been characterized using EDXRF, AAS, TGA, PXRD, IR and UV-visible analyses. The heterogeneous iron(III)–cyclam has been found to be capable of hydroxylating C–H bonds as strong as those in cyclohexane (BDE = 99.7 kcal mol⁻¹) using benign H₂O₂ at room temperature. The reactivity of the heterogeneous catalytic system is found to significantly improve in comparison with that of cis-[Fe^III(cyclam)Cl₂]Cl/H₂O₂ under homogeneous conditions. The catalytic reactions are marked by a very high selectivity for alcohols which is comparable with the best known non-heme catalysts with H₂O₂. The results critically reflect the role of the clay matrix surrounding the cationic metal complex in tuning the catalytic activity and selectivity of alkane hydroxylation.