Trans effect and inverse trans effect in MLX5 complexes (M=Mo, U; L=O, S; X=Cl, Br): A rationalization within density functional theory study

Trans effect in MLX5 complexes in which M is Mo or U metal, L is oxygen or sulphur and X a halide, are theoretically studied with density functional theory. In these octahedral complexes, the axial M-X bond length differs from the equatorial M-X one, and this difference depends on the relative electronegativity of the ligands, and of the total charge of the complexes (i.e. the oxidation degree of the metal). Fragment interaction energies, molecular orbital compositions and charge analysis are used to interpret the variation in the structures.