Oxo-Transfer Reactions of Chromium and Titanium Porphyrins

Abstract

<p>Examples of intermetal oxygen atom transfer are rare. In general, inner-sphere electron transfer mediated through an oxo ligand typically leads to formation of .u-oxo-bridged products.1 For example, when (TPP)Cr1v=O is treated with Cr11(TPP) in toluene, formation of (TPP)Cr111-0-Cr111(TPP) is observed. 2•3 lntermetal oxo transfer thus far has been limited to molybdenum and tungsten complexes.4 Oxo transfer between two ruthenium centers has been implicated in the aerobic epoxidation of olefins by ruthenium porphyrins.5 As an extension of our studies on inner-sphere redox reactions and nitrogen atom transfer,6 we have initiated an investigation of oxygen atom transfer. Our approach to oxo transfer developed as a result of our recent finding that nitrogen atom transfer occurs reversibly between (OEP)Mn==N and (TTP)Mn-CI as shown in eq 1.</p>