Dr Frank Mair (BSc, PhD, MRSC CChem) - research
1. Ligand design.
Our most significant contribution to the practise of co-ordination chemistry was the first demonstration of the exceptional steric control offered by incorporation of ortho-bulk into the aryl groups of diaryldiketiminate monoanionic ligands. Our 1998 paper1 reporting a potassium complex concluded that "The effectiveness of encapsulation that this ligand topology offers promises rich rewards in wide areas of chemistry". 479 hits for that ligand anion in the CCDC (as at 30/03/07) prove the prescience of this remark.
Then we alkylated the anion to prepare neutral b-diimines. These were originally viewed as competitors to the bulky a-diimines repopularised by Brookhart and others, but the absence of p-acceptor character renders them very weak ligands.2 This led to two parallel developments, both directed at olefin and ethylene polymerization catalysis.
The first path: reduce the ligands, highly diastereoselectively, to make racemic 1,3 diamines,3 lithiate, to make diamido anions,4 (figure 2) then metathesise with TiCl4, to make racemic C2-symmetric diamidotitanium catalysts,5 (Figure 3) desymmetrised and bulkier analogues of McConville?s diamidotitanium catalysts.
The second path: Make super-bulky,strongly p-accepting a-diimines. This is ongoing, to be published. It has parallel applications in polymerization catalysis, and in the promotion of new and unusual reactions, see section 3.
Aside from these amido ligands, derived from b-diketiminates by alkylation followed by reduction, we have developed further elaborations of b-diketiminates, summarised in Scheme 1.