Structures of monomeric octahedral d 2 rhenium(V) oxo complexes with oxygen atoms trans to the oxo ligands: Complexes with ethoxo ligands trans to O(oxo)

Specific features of the structure of mononuclear octahedral rhenium(V) complexes with oxygen atoms of ethoxo ligands trans to the multiply bonded oxo ligands have been considered. The complexes contain inorganic or organic monodentate ligands, as well as organic bi-, tri-, and tetradentate ligands in the equatorial plane. It has been noted that the Re-O(OEt)trans bonds, like the other bonds with alkoxy ligands ORalk (in particular, Re-O(OMetrans)) are not elongated owing to the structural manifestation of the trans influence of multiply bonded oxo ligands; rather, they are significantly shortened. This fact is explained by that the Re-O(ORalk) bonds are also multiple; i.e., the oxo alkoxo complexes should been considered as pseudo-dioxo compounds Re(=O)(=ORalk).