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2-(2-Hydroxy-4-methoxybenzoyl)benzoic acid derivatives of group 4 metal alkoxides

Boyle, Timothy; Yonemoto, Daniel T.; Neville, Michael L.

Continued exploration of the coordination behavior of derivatives of 2-benzophenone-based ligands with metal alkoxides ([M(OR)4]) was undertaken from the reaction of 2-(2-hydroxy-4-methoxybenzoyl)benzoic acid (H2-OBzA) with a series of Group 4 precursors. The products of these reactions were identified as: [(OR)2Ti(-(c,c-OBzA))]2 (OR = OCHMe2 (OPri; 1 •2tol); OCMe3 (OBu t; 2 •THF); OCH2CMe3 (ONep; 3)), [[(OPri)3Ti(-OPri)Ti(OPri) 2]2(-(c,-OBzA))2]2 (4), [(ONep)3Zr(-ONep)2Zr(ONep)2] 2(-(c,-OBzA)2) (5 •tol), [(py)(OBut) 3Zr]2(-(c,c-OBzA)) (6), [(OBut) 2Hf(-OBut)]2(-(c,η1-OBzA)) (7) where c = chelating or η2; = bridging or η1, η1(O,O); and c = bridging chelating or η1,η1(O,O); η2: η1. The metal centers for each of these compounds adopt a pseudo-octahedral geometry employing the OBzA ligand in numerous binding modes. The different functional oxygens (carboxylate, hydroxyl, and carbonyl) were employed in a variety of coordination modes for 1-7. The complexity of these OBzA-modified compounds is driven by a combination of the coordination behavior of the OBzA moieties, the size of the metal cation, and the pendant chain of the OR ligand. Solution NMR indicates a complex structure exists in solution that was considered to be consistent with the solid-state structure. © 2014 Taylor & Francis.