The first structural characterisation of a group 2 metal alkylperoxide complex: comments on the cleavage of dioxygen by magnesium alkyl complexes |
| |
Authors: | Bailey Philip J Coxall Robert A Dick Caroline M Fabre Sylvie Henderson Louise C Herber Christian Liddle Stephen T Loroño-González Daniel Parkin Andrew Parsons Simon |
| |
Institution: | Department of Chemistry, The University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh, EH9 3JJ, UK. Philip.Bailey@ed.ac.uk |
| |
Abstract: | A new high-yield synthesis of (PhCH(2))(2)Mg(thf)(2)] and (PhCH(2))CH(3)Mg(thf)](2)] via benzylpotassium has allowed a simple entry into benzylmagnesium coordination chemistry. The syntheses and X-ray crystal structures of both (eta(2)-Me(2)NCH(2)CH(2)NMe(2))Mg(CH(2)Ph)(2)] and eta(2)-HCC(CH(3))NAr'](2)Mg(CH(2)Ph)(thf)] (Ar'=2,6-diisopropylphenyl) are reported. The latter beta-diketiminate complex reacts with dioxygen to provide a 1:2 mixture of dimeric benzylperoxo and benzyloxo complexes. The benzylperoxo complex eta(2)-HCC(CH(3))NAr'](2)Mg(mu-eta(2):eta(1)-OOCH(2)Ph)](2)] is the first example of a structurally characterised Group 2 metal-alkylperoxo complex and contains the benzylperoxo ligands in an unusual mu-eta(2):eta(1)-coordination mode, linking the two five-coordinate magnesium centres. The Obond]O separation in the benzylperoxo ligands is 1.44(2) A. Reaction of the benzylperoxo/benzyloxo complex mixture with further eta(2)-HCC(CH(3))NAr'](2)Mg(CH(2)Ph)(thf)] results in complete conversion of the benzylperoxo species into the benzyloxo complex. This reaction, therefore, establishes the cleavage of dioxygen by this system as a two-step process that involves initial oxygen insertion into the Mgbond]CH(2)Ph bond followed by Obond]O/Mgbond]C sigma-bond metathesis of the resulting benzylperoxo ligand with a second Mgbond]CH(2)Ph bond. The formation of a 1:2 mixture of the benzylperoxo and benzyloxo species indicates that the rate of the insertion is faster than that of the metathesis, and this is shown to be consistent with a radical mechanism for the insertion process. |
| |
Keywords: | alkylperoxo ligand magnesium N ligands oxygen |
本文献已被 PubMed 等数据库收录! |
|