Field-Induced Slow Magnetic Relaxation in a Mononuclear Manganese(III)-Porphyrin Complex.
We report on a novel manganese(III)-porphyrin complex with the formula [Mn(III) (TPP)(3,5-Me2 pyNO)2 ]ClO4 ⋅CH3 CN (2; 3,5-Me2 pyNO=3,5-dimethylpyridine N-oxide, H2 TPP=5,10,15,20-tetraphenylporphyrin), in which the Mn(III) ion is six-coordinate with two monodentate 3,5-Me2 pyNO molecules and a tetradentate TPP ligand to build a tetragonally elongated octahedral geometry. The environment in 2 is responsible for the large and negative axial zero-field splitting (D=-3.8 cm(-1) ), low rhombicity (E/|D|=0.04) of the high-spin Mn(III) ion, and, ultimately, for the observation of slow magnetic-relaxation effects (Ea =15.5 cm(-1) at H=1000 G) in this rare example of a manganese-based single-ion magnet (SIM). Structural, magnetic, and electronic characterizations were carried out by means of single-crystal diffraction studies, variable-temperature direct- and alternating-current measurements and high-frequency and -field EPR spectroscopic analysis followed by quantum-chemical calculations. Slow magnetic-relaxation effects were also observed in the already known analogous compound [Mn(III) (TPP)Cl] (1; Ea =10.5 cm(-1) at H=1000 G). The results obtained for 1 and 2 are compared and discussed herein.
Instituto de Ciencia Molecular (ICMOL), Universitat de València, Paterna 46980, València (Spain).
Alejandro
A
Pascual-Álvarez
Instituto de Ciencia Molecular (ICMOL), Universitat de València, Paterna 46980, València (Spain).
Julia
J
Vallejo
Instituto de Ciencia Molecular (ICMOL), Universitat de València, Paterna 46980, València (Spain). emilio.pardo@uv.es.
Emilio
E
Pardo
Instituto de Ciencia Molecular (ICMOL), Universitat de València, Paterna 46980, València (Spain).
Miguel
M
Julve
Instituto de Ciencia Molecular (ICMOL), Universitat de València, Paterna 46980, València (Spain).
Francesc
F
Lloret
National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, Florida 32310 (USA).
J
J
Krzystek
Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, Cosenza, 87036 (Italy).
Donatella
D
Armentano
Institut Néel, CNRS, Nanoscience Department, BP 166, 380412 Grenoble Cedex 9 (France).
Wolfgang
W
Wernsdorfer
Instituto de Ciencia Molecular (ICMOL), Universitat de València, Paterna 46980, València (Spain). joan.cano@uv.es.|Fundació General de la Universitat de València (FGUV), Universitat de València, Paterna 46980, València (Spain). joan.cano@uv.es.
Joan
J
Cano
D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D008024:Ligands; D059346:Magnets / Q000737:chemistry; D008345:Manganese / Q000737:chemistry*; D008665:Metalloporphyrins / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D013696:Temperature
C509964:5,10,15,20-tetraphenylporphyrin; D008024:Ligands; D008665:Metalloporphyrins; D011166:Porphyrins; D011725:Pyridines; D008345:Manganese; C521455:3,5-dimethylpyridine
EPR spectroscopy; complete active space (CAS) calculations; magnetic materials; manganese; porphyrinoids