Electronic Structure and Magnetic Properties of Y2Ti(μ-X)2TiY2 (X, YH, F, Cl, Br) Isomers

The electronic structure and magnetic properties of homodinuclear titanium(III) molecules with halide and hydride ligands have been studied using single- and multireference methods. Natural orbital occupation numbers suggest that the singlet states are essentially diradical in character. Dynamic electron correlation is required for calculating quantitatively accurate energy gaps between the singlet and triplet states. Isotropic interaction parameters are calculated, and three of the compounds studied are predicted to be ferromagnetic at the MRMP2/ TZV(p) level of theory. Zero-field splitting parameters are determined using CASSCF and MCQDPT spinorbit coupling with three different electron operator methods. Timings for these methods are compared. Calculated dimerization energies suggest that all dimers studied are lower in energy than the corresponding monomers. Monomer structures and vibrational frequencies are reported.