A square-planar tetracoordinate oxygen-containing Ti<inf>4</inf>O <inf>17</inf> cluster stabilized by two 1,1′-ferrocenedicarboxylato ligands

Abstract

By introducing steric constraints into molecular compounds, it is possible to achieve atypical coordination geometries for the elements. Herein, we demonstrate that a titanium-oxo cluster [{Ti4(μ4-O) (μ2-O)2}(OPri)6(fdc) 2], which possesses a unique edge-sharing Ti4O 17 octahedron tetramer core, is stabilized by the constraints produced by two orthogonal 1,1′-ferrocenedicarboxylato (fdc) ligands. As a result, a square-planar tetracoordinate oxygen (ptO) can be generated. The bonding pattern of this unusual anti-van'tHoff/LeBel oxygen, which has been probed by theoretical calculations, can be described by two horizontally σ-bonded 2px and 2py orbitals along with one perpendicular nonbonded 2pz orbital. While the two ferrocene units are separated spatially by the ptO with an Fe⋯Fe separation of 10.4Å, electronic communication between them still takes place as revealed by the cluster's two distinct one-electron electrochemical oxidation processes. A square-planar tetracoordinate oxygen (ptO) is realized in an edge-sharing Ti4O17 octahedron tetramer stabilized by two orthogonal 1,1′-ferrocenedicarboxylato ligands. Whereas the two ferrocene units are separated spatially by the ptO with an Fe⋯Fe separation of 10.4Å, the electronic communication between them still takes place as indicated by the cluster's two distinct one-electron electrochemical oxidation processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.