Diketiminate ligands

The substituents on the ancillary /3-diketiminate ligand play a crucial role in determining the activity of these catalysts. Hence, although (335) and (336) are highly active, the less bulky (337) and (338) are inactive. The most active example reported is (339) which produces 558 g polymer/g [Zn]/h. 

A review of complexes of /3-diketiminate ligands (155) contains little material on iron complexes. ... 

The sterically encumbering /3-diketiminate ligand [ HC (MeCDippN)2Ga ] (Dipp = C6H3-2,6-Pr2) has been... 

Compared to ligands L22 and L23, L24 is a bulkier P-diketiminate ligand by altering methyl with wo-propyl on A -aryl substituents on L23. L24 has been broadly used in rare-earth metal chemistry and many interesting complexes have been studied. 

All tris-P-diketiminato complexes 130-134 exhibited high catalytic activity for the ROP of e-caprolactone and L-lactide. a,co-dihydroxytelechelic polymers in high yield with high molar mass and moderate molar mass distributions (Mw/M = 1.38-1.89) were produced from the ROP of e-caprolactone (Scheme 8) catalyzed by 130-134.130-134 are highly active catalysts for the ROP of L-lactide to produce polylactide (Scheme 14). The electronic factor of the P-diketiminate ligand largely affects the catalytic activity of the complexes. 131 containing an... 

Figure 1. Left General structure of a (3-diketiminate ligand with aryl substituted nitrogen groups. Right The coordination wedge of a metal complex with LMe,zPr2 (R = Me, R = H, R" = zPr, R//z = H), depicting how the R" groups block the axial sites of the metal atom (shown in black).

In this chapter we collect representative procedures for the preparation of the most popular family of /V-aryl p-diketiminate ligands, and of alkali metal and thallium salts that are especially useful precursors to transition metal complexes. We then describe the preparation of a series of useful p-diketiminato metal complexes with 3d transition metals from Sc to Zn, each of which serves as a template for further elaboration. 

The [3-diketiminate ligand HLMe,Me3 was first reported by Budzelaar via condensation of acetylacetone with 2,4,6-trimethylaniline in 12 N HC1 at 120-140°C.1 We find that the milder procedure below for HLMe,Me3 adapted from Budzelaar s method for HLMe,Me2 offers a simple workup and is also versatile for the synthesis of other HLMe,R derivatives.2 We also include spectroscopic information for HLMe,Me2 that was prepared analogously. The synthesis of the thallium derivative xiLMe,Me3 was adapted from the published literature procedures for xiLMe,Me2 and xiLMe,Me3.3,4... 

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