Abstract
A series of tantalum imido and amido complexes supported by a pyridine-linked bis(phenolate) ligand has been synthesized. Characterization of these complexes via X-ray crystallography reveals both C s and C 2 binding modes of the bis(phenolate) pyridine ligand, with complexes containing two or fewer strong jr-donor interactions from ancillary ligands giving C s symmetry, whereas three strong jr-donor interactions (e.g., three amido ligands or one amido ligand and one imido ligand) give C 2-symmetric binding of the bis(phenolate)pyridine ligand. DFT calculations and molecular orbital analyses of the complexes have revealed that the preference for C s-symmetric ligand binding is a result of tantalum - phenolate π-bonding, whereas in cases where tantalum - phenolate π-bonding is overridden by stronger Ta - N π-bonding, C 2-symmetric ligand binding is preferred, likely because conformationally this is the lowest-energy arrangement. This electronically driven change in geometry indicates that, unlike analogous metallocene systems, the bis(phenolate)pyridine pincer ligand is not a strong enough π-donor to exert dominant control over the electronic and geometric properties of the complex.
Original language | English (US) |
---|---|
Pages (from-to) | 5096-5105 |
Number of pages | 10 |
Journal | Inorganic chemistry |
Volume | 48 |
Issue number | 12 |
DOIs | |
State | Published - Jun 15 2009 |