Structural and spectroscopic characterisation of the holmium double-decker partially oxidised and bi-radical phthalocyanine complexes with iodine

Two crystals of holmium(III) double-decker iodine doped phthalocyanines, HoPc2I5/3 (I) and HoPc2I (II), were grown directly in the reaction of holmium chips with 1,2-dicyanobenzene under versatile quantity of iodine at 180–160 °C. The complex I crystallises in the P4/mcc space group of tetragonal system, while the complex II crystallises in the P2/c space group of monoclinic system. The space group of P4/mcc and z = 1 requires that the Ho(III) atom is statistically disordered in the HoPc2I5/3 structure. The iodine atoms form linear symmetrical triiodide I 3 - ions in I, while the I− ions in II. Assignment of iodine species as I 3 - in the HoPc2I5/3 and I− in HoPc2I complexes point to the +5/9 and +1 oxidation state of the HoPc2 unit in these complexes. Thus one Pc macrocycle of the double-decker HoPc2 units has a non-integer oxidation state of −1.222 in I, while both Pc-rings are one-electron oxidised radical Pc− in II. Magnetic susceptibilities of HoPc2I5/3 and HoPcI at room temperature are 4.56 × 10−2 and 5.12 × 10−2 emu/mol and the calculated magnetic moments are 10.46 and 11.08 μB, respectively. UV–Vis spectroscopic measurement of I and II in benzene solution were carried out and discussed.