Structural Features of Monomeric Octahedral d²-Rhenium(V) Monooxo Complexes with Oxygen Atoms of Tridentate Chelating (O,P,O and O,P,N) Ligands

Abstract

The structural features of eleven mononuclear octahedral d²-Re(V) monooxo complexes with tridentate chelating (O,P,O and O,P,N) ligands, [ReO$\left( {{\text{L}}_{{{\text{tri}}}}^{m}} \right)$$\left( {{\text{L}}_{{{\text{bi}}}}^{n}} \right)$], [ReO$\left( {{\text{L}}_{{{\text{tri}}}}^{m}} \right)$Cl₂], and [ReO$\left( {{\text{L}}_{{{\text{tri}}}}^{m}} \right)$-Cl(PPh₃)], are considered. The Re–O${{\left( {{\text{L}}_{{{\text{tri}}}}^{m}} \right)}_{{trans}}}$ bond lengths are commensurable (or somewhat shorter) with the Re–O${{\left( {{\text{L}}_{{{\text{tri}}}}^{m}} \right)}_{{cis}}}$ 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 Re–O${{\left( {{\text{L}}_{{{\text{bi}}}}^{{\text{2}}}} \right)}_{{trans}}}$ bonds are, on average, 0.094 Å longer than Re–O(ST) and 0.189 Å longer than Re–O${{\left( {{\text{HL}}_{{{\text{bi}}}}^{{\text{3}}}} \right)}_{{cis}}}$, in accordance with the structural consequences of the trans-effect of a multiply bonded oxo ligand.