The Structure of Monomeric Octahedral d2-Rhenium(V) Monooxo Complexes [ReO(Lmtri)(Lnbi)], [ReO(Lmtri)Cl2] with Oxygen Atoms of Tridentate Chelating (O,S,O and S,O,S) Ligands

The structural features of eleven mononuclear octahedral d2-Re(V) monooxo complexes with tridentate chelating (O,S,O and S,O,S) ligands, $$\left[ {{\text{ReO}}\left( {\text{L}_{\text{tri}}^{m}} \right)\left( {\text{L}_{\text{bi}}^{n}} \right)} \right],$$$$\left[ {{\text{ReO}}\left( {\text{L}_{\text{tri}}^{m}} \right){\text{C}}{{{\text{l}}}_{{\text{2}}}}} \right]$$, are discussed. The $${\text{Re-O}}{{\left( {\text{L}_{\text{tri}}^{m}} \right)}_{{trans}}}$$ bond lengths (except for two cases) were shown to be similar to (or somewhat shorter than), the Re–O(L)cis or Re–O(ST) bond lengths, which is indicative of the presence of pseudo-dioxo ReO2 groups with increased bond orders for both trans-arranged Re–O bonds. In the structures of two compounds, the $${\text{Re-O}}{{\left( {\text{L}_{\text{tri}}^{m}} \right)}_{{trans}}}$$ bonds are, on average, 0.093 Å longer than the Re–O(ST) bonds, which is consistent with the structural requirements of the trans-effect of a multiply bonded oxo ligand.