Ab initio calculation for magnetostructural characterization of azido-bridged Cu(II) dimers

On basis of the broken symmetry approach and density functional theory (DFT ), the magnetostructural characterization of azido - bridged Cu ( II) dimer s is studied which have end - to - end (EE) and end - on (EO) two main coor dination modes. The calculating results show that EE mode gives antiferroma gnetic interaction, whereas EO mode gives ferromagnetic coupling in which t heta is about 91 degrees - 107 degrees, basically agreealde with the experi mental value 96 degrees - 104 degrees. The essence of the magnetostructural characterization lies in d- p- d three centers sigma antibonding action be tween two Cu d, orbitals and bridged N p(x) orbital in SOMO b(Ig). In the t heta region of 95 degrees - 110 degrees the sigma antibonding overlap has t he maximum, which leads to the maximum ferromagnetic coupling. It is also s hown that tau has no great influence on J, whereas J decreases linearly wit h increasing r(Cu - N mu).