Magnetic Phase Transition in a Heteromolecular Hydrogen-Bonded Complex of Nitronylnitroxide Radicals

Abstract

An organic molecular acid-base complex has been synthesized from pyridine-substituted biradical 2 in a triplet (S = 1) ground state and a benzoic acid derivative of monoradical 3 with S = 1/2. The two constituent molecules are bound by an OH-N hydrogen bond in a crystalline solid state. The complex has been found to exhibit an antiferromagnetic phase transition at 5 K. The complex is the first example of a hydrogen-bonded heterospin, heteromolecular complex exhibiting a magnetic phase transition in purely organic molecule-based materials.

Co-crystallisation of thiazyl radicals: preparation and crystal structure of [PhCNSSN][C6F5CNSSN]

“…The introduction of potentially strong non-covalent interactions between radicals A and B which are not present in either A or B should stabilise the formation of such co-crystals. 7 In this paper we describe the use of a perfluorophenyl-phenyl interaction 8 of ca. 30 kJ mol À1 to drive the formation, using The parent radicals 1c and 2c were prepared according to literature methods † and purified by vacuum sublimation to yield green-black needles of (1) 2 and deep red, well-faceted crystals of (2) 2 suitable for X-ray diffraction.…”

Synthesis, Structure and Magnetic Properties of 1‐D Silver(I) Complexes with Benzoic Acids Bearing Ortho‐Imino Nitroxide and Para‐Nitronyl Nitroxide Radical Ligands

“…Benzoic acid-substituted para-nitronyl nitroxide, IT-pBAH and ortho-imino nitroxide M-oBAH free radicals (IM-oBAH = 2-(2-carboxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-yloxyl, NIT-pBAH = 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-3-oxido-1H-imidazol-3-ium-1-yloxyl) were prepared in good yield according to a general method reported previously. [19][20][21]…”

Pyridine-substituted nitronyl nitroxide biradicals: a triplet (S = 1) ground state lasting out N-methylation

“…Hydrogen-donating and -accepting molecules such as phenol, carboxylic acid, and pyridine derivatives, have been introduced into the stable radical family of nitroxide and imino-or nitronyl nitroxide. [14][15][16][17] The magnetic properties of these compounds have been examined in view of hydrogen-bonded assemblage of the open-shell building blocks. [14][15][16][17] Electrostatic forces between ionic charges have been introduced onto stable nitronyl nitroxide radicals, 18 which contributed to the successful control of molecular arrangements suitable for intermolecular magnetic exchange interactions.…”

“…[14][15][16][17] The magnetic properties of these compounds have been examined in view of hydrogen-bonded assemblage of the open-shell building blocks. [14][15][16][17] Electrostatic forces between ionic charges have been introduced onto stable nitronyl nitroxide radicals, 18 which contributed to the successful control of molecular arrangements suitable for intermolecular magnetic exchange interactions. Most of the molecular and crystal engineering approaches based on noncovalent bonding have been applied only to doublet (S = 1/2) radicals.…”