Windmill-shaped octanuclear Zn-4(II)/Ln(4)(III) (Ln(III) = Dy, Tb, Ho) heterometallic ensembles supported by a tetraferrocene scaffold

Utilizing a new ferrocene-based compartmental ligand, H4L (1), a series of novel heterometallic complexes [{LZn(mu-OAc) Dy}(4)(mu(4)-H2O)] (2), [{LZn(mu-OAc) Tb}(4)(mu(4)-H2O)] (3), [{LZn(mu-OAc) Ho}(4)(mu(4)-H2O)] (4), [L = Fe[(C5H4 ){=C(Me)-N=NC6H3-(o-O)(m-O)}](2)] were synthesized and characterized. 2 and 3 crystallize in the monoclinic crystal system in the 12/m space group, whereas 4 crystallizes in the tetragonal crystal system in the 14/m space group. The tetra deprotonated ligand L4- has two distinct coordination compartments: one pocket (2N, 2O) suitable for the transition metal (3d) ions and another pocket (4O) suitable for lanthanide (4f) metal ions. Additionally, the terminal phenoxo group can be utilized for cluster expansion. In all the complexes, the Zn-II ion is in a perfect square pyramidal (2N, 3O) geometry whereas the lanthanide ion has a coordination number of eight (8O) in a distorted biaugmented trigonal-prism geometry. The electrochemical properties of 2 and 3 along with ligand H4L (1) were studied by cyclic voltammetry (CV). All the complexes display a similar type of electrochemical behavior viz., one quasi-reversible oxidation typical of a ferrocene/ferrocenium motif. The magnetic properties of all the complexes have also been investigated.