Local density discrete variational Xα calculations on transition-metal oxycation complexes: d–d and charge-transfer spectra of molybdenyl species

Theoretical d–d and charge-transfer electronic transition energies for the structurally characterised d1 MoO3+ complexes [MoOCl4]–, [MoOCl4(OH2)]–, [MoOBr4(OH2)]–, [MoOF5]2– and [MoO(NCS)5]2– are reported and compared with the most recent experimental data. The discrete variational Xα model gives excellent reproduction of band energies and assignments for each individual complex and for the whole series. With two minor exceptions, the experimental and theoretical results are in agreement and support the general validity of the Ballhausen–Gray picture of the electronic structure of d1 oxycation species.