Phenol-substituted nitronyl nitroxide biradicals with a triplet (S = 1) ground state

Synthesis, Crystal Structure and Magnetic Properties of a Trinuclear Copper(II) Complex Based on P-Cresol-Substituted Bis(α-Nitronyl Nitroxide) Biradical

“…Bond lengths of the N−O group within the four NN moieties are comprised in the range 1.254(6)–1.300(5) Å ( Table 2 ) with small elongation (0.03 Å) of the coordinated ones and are characteristic of free and coordinated nitroxide radicals [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. The O-N-C-N-O moieties are strictly planar ( Table 3 ), as expected due to electron delocalization.…”

“…Therefore, an almost unlimited number of open-shell molecules may be synthesized. Thus, nitronyl nitroxide have been grafted on alcanes [ 4 ], pyridine [ 5 , 6 , 7 , 8 , 9 , 10 ], imidazole [ 11 ], triazole [ 12 ], bipyridine [ 13 ], phenol [ 14 , 15 , 16 , 17 ], pyrene [ 18 ], azulene [ 19 ], phthalocyanine [ 20 ], porphyrin [ 21 ], cyclotriphosphazene [ 22 ], or even on graphene [ 23 ]. Most importantly, nitronyl nitroxide has one of the best stabilities among the free radicals, and this is retained in most of its derivative so that they can generally be handled under mild but normal conditions, even when coordinated with most metal ions.…”

“…This versatile but richness of magnetic behaviors prompt us to investigate complexation of copper(II) by bis-nitronyl nitroxide diradical 4-methyl-2,6-bis(1-oxyl-3-oxido-4,4,5,5-tetramethyl-2-imidazolin-2-yl)phenol [ 14 ] (NIT 2 PhOH, Scheme 1 ). Herein, we report the reaction with copper(II) chloride to afford a heterospin neutral complex [Cu II 3 (NIT 2 PhO) 2 Cl 4 ] where this diradical (NIT 2 PhOH) acts both as a bridging and chelating ligand.…”

Hyperfine structure of ESR spectra as a probe for heisenberg exchange couplings in nitroxide triradicals serving as building blocks for molecule-based ferrimagnets

“…Thus, the molecular design serving for the syntheses of the organic ferrimagnets is a challenging issue in materials science. We have examined the possible occurrence of the ferrimagnetic spin alignments in organic molecular assemblages both by experiments and by theoretical calculations in quantum terms [24][25][26][27][28][29][30][31][32].…”

Clustering of molecular spins in the crystals of nitronylnitroxide and iminonitroxide triradicals based on benzene-1,3,5-triyl frameworks

“…In the previous studies, 7 we have designed and synthesized a triradical 1 and 2 (Scheme 1) from a phenol-substituted biradical and a benzoic acid monoradical as a building block of ''single-component ferrimagnetics''. 8,9 The biradical based on a 2,4-disubstituted phenol is known to have a triplet (S = 1) ground state with the singlet-triplet energy gap of 2J p /k B = 26 K, 10 which is retained in the triradical 1 after the esterification. 7a,b The amplitude of the additional interactions, |J s1 | and |J s2 |, of 1 has been estimated to be in the order of 100 mK.…”