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Selective Crystallization of Four Bis(phthalocyaninato)neodymium(III) Polymorphs
preprintsubmitted on 13.07.2020, 13:56 and posted on 14.07.2020, 09:35 by Maegan Dailey, Claire Besson
Four polymorphs of bis(phthalocyaninato)neodymium(III) were reproducibly and selectively crystallized by the slow evaporation of saturated solutions. The obtained phase depended on the initial oxidation state of the NdPc2 molecule and the choice of solvent. Single-crystal X-ray diffraction studies were used to correct previous mis-identifications and provide missing coordinates for the γ-phase as well as a detailed comparison of molecular structure and crystal packing in all NdPc2 polymorphs. The primary feature in all phases is columnar stacking based on parallel π π interactions, with a variety of slip angles within those stacks as well as secondary interactions between them. Chemical redox and acid-base titrations, performed on re-dissolved crystals demonstrate that NdPc2+ and NdPc2- are easily obtained through weak oxidizing and reducing agents, respectively. Additionally, we show that the protonated form of the NdPc2- complex has a nearly identical UV-Vis spectra to that of neutral NdPc2, explaining some of the confusion over chemical composition in previously published literature.