Electronic Structure of 2,2′-Bipyridine Organotransition-Metal Complexes. Establishing the Ligand Oxidation Level by Density Functional Theoretical Calculations

摘要: A density functional theoretical (DFT) study (B3LYP) has been carried out on 20 organometallic complexes containing η(5)- and/or η(3)-coordinated cyclopentadienyl anions (Cp(-)) and 2,2'-bipyridine (bpy) ligand(s) at varying oxidation levels, i.e., as the neutral ligand (bpy(0)), π-radical monoanion (bpy(•-))(-), or diamagnetic dianion (bpy(2-))(2-). The molecular electronic structures of these species in their ground states and, some cases, first excited have calculated using broken-symmetry methodology. results are compared with experimental structural spectroscopic data (where available) order to validate DFT computational approach. following electron-transfer series studied: [(Cp)(2)V(bpy)](0,+,2+) (1-3), [(Cp)(2)Ti(bpy)](-,0,+,2+) (4-7), [(Cp)(2)Ti(biquinoline)](0,+) (8 9), [(Cp*)(2)Ti(bpy)](0) (10) (Cp* = pentamethylcyclopentadienyl anion), [Cp*Co(bpy)](0,+) (11 12), [Cp*Co(bpy)Cl](+,0) (13 14), [Fe(toluene)(bpy)](0) (15), [Cp*Ru(bpy)](-) (16), [(Cp)(2)Zr(bpy)](0) (17), [Mn(CO)(3)(bpy)](-) (18). In test predictive power our computations, we also two complexes, B, namely, dimer [Cp*Sc(bpy)(μ-Cl)](2) (A) paramagnetic (at 25 °C) mononuclear [(η(5)-C(5)H(4)(CH(2))(2)N(CH(3))(2))Sc((m)bpy)(2)] (B). crystallographically observed intramolecular π-π interaction N,N'-coordinated leading an S 0 state is reliably reproduced. Similarly, small singlet-triplet gap ~600 cm(-1) between antiferromagnetically coupled (bpy(•-))(-) ligands ferromagnetically radical triplet B Therefore, confident that can present computationally obtained, detailed for 1-18. We show bpy(0) behave very weak π acceptors (if all), whereas (bpy(2-))(2-) dianions strong π-donor ligands.