A series of metal complexes with the non-innocent N,N'-bis(pentafluorophenyl)-o-phenylenediamido ligand: twisted geometry for tuning the electronic structure.

A series of homoleptic complexes with non-innocent ligands derived from N,N'-bis(pentafluorophenyl)-o-phenylenediamine (H(2)(F)pda) are reported. [Ni(II)((F)sbqdi)(2)] (1), [Pd(II)((F)sbqdi)(2)] (2), [Co(II)((F)sbqdi)(2)] (3), and [Cu(II)((F)sbqdi)(2)] (4) were synthesized, where ((F)sbqdi)(1-) represents a radical anion formed by one-electron oxidation of the doubly deprotonated H2(F)pda. The oxidation states of ligands and metals in complexes 1-4 were assigned by single crystal X-ray crystallography performed at low temperatures. Complex 4 is the first Cu(II) complex where both o-phenylenediamine derived ligands are monoanionic radicals. The bulky N-C6F5 substituents force the complexes 1, 3, and 4 to adopt a twisted geometry (intermediate between square-planar and tetrahedral). The electronic structures of the neutral compounds 1-4 and of some of their cationic and/or anionic neighboring redox states were probed using EPR and UV-VIS-NIR spectroelectrochemistry. The twisted geometry of the complexes results in considerable changes in their electronic structures compared to the well known square-planar complexes while the strongly electron withdrawing N-C6F5 groups have a great influence on redox properties.