Solid state pi-pi stacking and higher order dimensional crystal packing, reactivity, and electrochemical behaviour of salphenazine actinide and transition metal complexes

Condensation of a 2,3-diaminophenazine or 2,3-diamino-2-quinoxalinol with two equivalents of 3,5-ditertbutylsalicylaldehyde affords new Schiff base ligands. Here, we describe and compare the synthesis, UV-Vis, electrochemical, solution, and solid state behaviour of the free base, salphenazine ligand [L^I], and M[L^I] complexes, where M = UO₂(VI), Cu(II), VO(IV), Zn(II), Co(II), and Ni(II). The change in π-overlap and π-stacking between molecules and long-range ordering of the solid-state structure is vastly different depending on the size and electronic character of the metal. A sterically constrained μ-oxo Fe(III) dimer complex is also reported.