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Ligand π‐Radical Interaction with f‐Shell Unpaired Electrons in Phthalocyaninato–Lanthanoid Single‐Molecule Magnets: A Solution NMR Spectroscopic and DFT Study
Author(s) -
Damjanović Marko,
Morita Takaumi,
Katoh Keiichi,
Yamashita Masahiro,
Enders Markus
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201501944
Subject(s) - chemistry , unpaired electron , hyperfine structure , crystallography , lanthanide , ligand (biochemistry) , molecule , cationic polymerization , proton nmr , fermi contact interaction , multiplicity (mathematics) , stereochemistry , ion , atomic physics , mathematical analysis , biochemistry , physics , receptor , mathematics , organic chemistry
The phthalocyaninato double‐decker complexes [M(obPc) 2 ] 0 (M= Y III , Tb III , Dy III ; obPc=2,3,9,10,16,17,23,24‐octabutoxyphthalocyaninato), along with their reduced ([M(obPc) 2 ] − [P(Ph) 4 ] + ; M=Tb III , Dy III ) and oxidized ([M(obPc) 2 ] + [SbCl 6 ] − (M=Y III , Tb III ) counterparts were studied with 1 H, 13 C and 2D NMR. From the NMR data of the neutral (i.e., with one unpaired electron in the ligands) and anionic Tb III complexes, along with the use of dispersion corrected DFT methods, it was possible to separate the metal‐centered and ligand‐centered contributions to the hyperfine NMR shift. These contributions to the 1 H and 13 C hyperfine NMR shifts were further analyzed in terms of pseudocontact and Fermi contact shifts. Furthermore, from a combination of NMR data and DFT calculations, we have determined the spin multiplicity of the neutral complexes [M(obPc) 2 ] 0 (M=Tb III and Dy III ) at room temperature. From the NMR data of the cationic Tb III complex, for which actually no experimental structure determination is available, we have analyzed the structural changes induced by oxidation from its neutral/anionic species and shown that the interligand distance decreases upon oxidation. The fast electron exchange process between the neutral and anionic Tb III double‐decker complexes was also studied.