Structural details of monomeric octahedral d ²-rhenium(V) oxo complexes with oxygen atoms in the trans-positions to oxo ligands. Complexes with the anionic ligands or ^n- (n = 1, 2) in trans-positions to O(oxo)

The paper considers details of the structures of mononuclear octahedral rhenium(V) oxo complexes with oxygen atoms of aromatic (phenolic) and other similar cyclic ligands OR− (R = Ph, Cy, C6H4R′ (R′ = OH, OMe), C10H6OH) and with other structurally studied anionic ligands ORn− (n = 1, 2) (R = P(O)(OMe)2, C(O)(CF3), OC(Me(CF3)2, BF3) located in the trans-position to the multiply bonded oxo ligands. The complexes contain halide ligands and organic mono-, bi-, and tetradentate ligands in the equatorial plane. The Re-O(OR)trans bonds as well as the bonds with aliphatic alkoxo ligands (ORalk)trans (R = Me, Et, Pr) are not elongated due to the trans-effect of doubly bonded oxo groups but are substantially shortened (with one exception). This is attributable to the fact that these Re-O(OR) bonds, like Re-O(oxo) bonds, have a higher order, i.e., d2-rhenium(V) complexes of this type should be treated as pseudo-dioxo compounds [Re(=O)(=OR)]3 − n (n = 1, 2).