Theoretical study on single-molecule electron conductivity of paddlewheel-type dichromium(II,II) tetracarboxylate complexes

A relationship between the single-molecule electron conductivity, spin states, and substituents is investigated on the paddlewheel-type dichromium(II,II) tetracarboxylate complexes as the simplest model of the extended metal atom chains. The electronic structures and single-molecule electron conductivity of some model complexes with different substituents are calculated by the broken-symmetry density functional theory and elastic scattering Green's functions methods, respectively. The calculated results indicate that the electron conductivity of the complexes is changed by the electron-donating/withdrawing groups introduced into the bridging ligands. In addition, it is also found that a ratio of the electron conductivities between the antiferromagnetic and ferromagnetic coupling states in the Cr(II)2unit can be changed by these substituents. These results suggest that the electron conductivity of these complexes can be controlled by changing the spin state.Graphical Abstract