659741-95-4Relevant academic research and scientific papers
A sterically demanding enolate ligand: Tantalum ligation and pyridine coupling
Soo, Han Sen,Diaconescu, Paula L.,Cummins, Christopher C.
, p. 498 - 503 (2004)
Enolate ligands of formula [OC(Ad)Ar]- (Ad = 2-adamantylidene; Ar = 3,5-C6H3Me2 1a, Ar = 2,4,6-C6H2Me3 1b) were designed and prepared as potassium salts to mimic the topology of related N-tert-hydrocarbyl and ketimide ligands. Subsequently, trimethyltantalum bis-enolate complexes TaMe3(O-C[Ad]Ar)2 (Ar = 3,5-C6H3Me2 2a, Ar = 2,4,6-C6H2Me3 2b) were prepared in good yields from a salt metathesis reaction between TaMe3Cl2 and 2 equiv of the corresponding potassium enolate. Complex 2a was structurally characterized and found to be monomeric in the solid state and to exhibit an inner coordination sphere of approximate D3h symmetry. Reaction between 2a and pyridine in the presence of dihydrogen resulted in an unanticipated pyridine coupling with formation of the bipyridine complex TaMe(O-C[Ad](3,5-C6H3Me2))2(py)(bpy) , 3a (py = pyridyl, bpy = 2,2′-bipyridyl), which was structurally characterized to confirm its formulation. Labeling experiments using pyridine-d5 and D2 suggest that formation of the tantalum(III) complex 3a occurred via C-H activation involving a putative tantalum(III) intermediate, TaMe-(O-C[Ad](3,5-C6H3Me2))2 (py)3, 4a.
