A density functional study on magnetic exchange interaction between Mn(II) ion and nitronyl nitroxide radical in trans- and cis-metal-radical complexes

The magneto-structural correlation between a Mn(II) ion, coordinated in an octahedral environment, and two nitronyl nitroxide radical ligands in trans- and cis-metal-radical complexes is investigated by the broken symmetry (BS) approach within density functional theory (DFT). The dependences of coupling constants Jon three structural parameters: (i) bond angle theta (Mn-O-N (nitroxide)); (ii) rotating angle psi, defined by the nitronyl nitroxide radical plane rotating around the axial Mn-O (nitroxide); (iii) bond distance R (Mn-O (nitroxide)) are directly calculated. Our calculations showed that both trans- and cis-Mn(II)-radical complexes behave a stronger antiferromagnetic interaction, consistent with experiments. In view of molecular orbital theory, the direct exchanges, including sigma-type and TT-type exchanges, are responsible for the magnetic exchange pathways. There is a preferable linear correlation between the calculated coupling constants J and the overlap integral squares S-ab(2), between the local magnetic orbitals at the various rotating angle psi at the fixed bond angle theta and bond distance R, in both trans- and cis-Mn(II)radical complexes.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000233366500003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, MultidisciplinarySCI(E)EI5ARTICLE5402-4144