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Magneto‐Structural Correlations in a 1,3,2‐Dithiazolyl Radical Crystal, BBDTA⋅GaBr 4 : Structure and Magnetic Properties of its Three Polymorphs
Author(s) -
Fujita Wataru,
Kikuchi Koichi
Publication year - 2009
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200800362
Subject(s) - antiferromagnetism , ferromagnetism , isostructural , magnetic susceptibility , crystallography , spin canting , crystal structure , spins , chemistry , condensed matter physics , materials science , magnetization , physics , magnetic field , quantum mechanics
Three attractions in one cage : Various magnetic networks are formed in the three polymorphs of an organic magnet, BBTDA(=benzo[1,2‐d:4,5‐d′]bis[1,3,2]dithiazole)⋅GaBr 4 . The three phases show quite different magnetic behaviors in spite of having the same chemical formula. Their magnetic differences originate from the relative configuration of the neighboring organic radical molecules in their crystals.We investigate the preparation, crystal growth, crystal structure, and magnetic properties of the three polymorphs (α, β, and γ) of an organic magnet, BBDTA(=benzo[1,2‐d:4,5‐d′] bis[1,3,2]dithiazole)⋅GaBr 4 , which is an S ‐1/2 system. In the α phase, BBDTA + units form a square‐planar lattice, and show canted antiferromagnetism with a magnetic coupling constant J / k B of −18 K and a canting angle of 0.15° below 15.5 K. The β phase is composed of a ferromagnetic regular chain with a J / k B value of +4.5 K and a strong antiferromagnetic chain with J / k B =−99 K, and shows ferromagnetic ordering in spins of purely the ferromagnetic chain below 0.4 K. The γ phase is isostructural with γ‐BBDTA⋅GaCl 4 , which is an organic ferromagnet below 7.0 K, and possesses antiferromagnetic interactions of J / k B =−60 K between BBDTA + cations, and shows no magnetic ordering until 2 K. The magnetic properties of these phases are quite sensitive to the molecular alignment in the crystals.