Computational study of the spin-state energies and UV-Vis spectra of bis (1,4,7-triazacyclononane) complexes of some first-row transition metal cations

We report here computed spin-state energies and UV-Vis spectra for several transition metal complexes with a triazacyclononane ligand. Our results show that the spin ground-state is correctly obtained with either OPBE or SSB-D, except for the high-spin ground-state of the Co(ii) complex that was properly described only by SSB-D. The UV-Vis spectra from TD-DFT reproduce in general rather well the experimental spectra, but in cases of the Cr(iii) and Co(ii) complexes it clearly failed. Better results for the UV-Vis spectra have been obtained by using Ligand Field DFTThe following organizations are thanked for financial support: the HPC-Europa2 Transnational Access program of the European Union, the Ministerio de Ciencia e Innovacion (MICINN, project number CTQ2011-25086/BQU), and the DIUE of the Generalitat de Catalunya (project number 2009SGR528), and Serbian Ministry of Science under project 172035. Financial support from MICINN (Ministry of Science and Innovation, Spain) and the FEDER fund (European Fund for Regional Development) was provided by grant UNGI08-4E-00