Synthesis and Characterization of Free and Coordinated Nitroxide and Nitronyl Nitroxide Diradicals with a 2,7-Naphthalene Coupling Unit

Synthesis and Characterization of Free and Coordinated Nitroxide and Nitronyl Nitroxide Diradicals with a 2,7-Naphthalene Coupling Unit Full article

Journal

Inorganic Chemistry
ISSN: 0020-1669

Output data

Year: 2026, Volume: 65, Number: 12, Pages: 6476–6491 Pages count : 16 DOI: 10.1021/acs.inorgchem.5c05421

Authors

Zlokazov Mikhail ¹ , Zayakin Igor ¹ , Romanenko Galina ² , Bogomyakov Artem ^2,3 , Smirnova Kristina ^2,3 , Zaitsev Konstantin ^2,3 , Fedin Matvey ^2,3 , Starikov Andrey ⁴ , Shangin Pavel ¹ , Syroeshkin Mikhail ¹ , Nasyrova Darina ¹ , Tretyakov Evgeny ¹

Affiliations

1	N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
2	International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Institutskaya Str. 3a, Novosibirsk 630090, Russian Federation
3	Novosibirsk State University, Pirogova Str. 1, Novosibirsk 630090, Russian Federation
4	Institute of Physical and Organic Chemistry, Southern Federal University, Stachka Ave. 194/2, Rostov-On-Don 344090, Russian Federation

A quantum-chemical investigation of nitroxide and nitronyl nitroxide diradicals with a 2,7-naphthalene coupling unit (bis-tert-butylnitroxide DR4, bis-nitronyl nitroxide DR6, and mixed tert-butylnitroxide/nitronyl nitroxide DR5) was carried out to predict conformation-dependent values of the intramolecular interactions. The coupling constants J are positive for symmetrical diradicals with tert-butyl-nitroxide or nitronyl nitroxide moieties (B3LYP/Def2-TZVPP: ∼440 and 60 K, respectively, for the most stable conformations), but it is negative for the mixed DR5 (∼−160 K). The triplet diradical DR4 was allowed to react with Mn(hfac)2 to give a polymer complex [Mn(hfac)2(DR4)]n exhibiting non-linear field dependencies of magnetization at low temperatures due to short-range ordering within the polymer chains. Attempts to synthesize the mixed diradical DR5 revealed that the tert-butyl-nitroxide moiety is not stable and undergoes a previously unobserved degradation pathway to give the corresponding α-carbonyl nitrone. At the same time, diradical DR6 was successfully prepared by using the palladium-catalyzed reaction of 2,7-dibromonaphthalene with a (nitronyl nitroxide-2-ide)(triphenylphosphine)gold complex. Magnetic susceptibility studies proved that the diradical DR6 has the triplet ground state with the energy gap ΔEST = ∼24 and ∼10–18 K in frozen (glassy) solution and solid state, respectively. Surprisingly, naphthalene-2,7-diyl is comparable as a ferromagnetic coupler with m-phenylene, which provides the singlet-triplet energy gap of value ΔEST = ∼46 K.

Zlokazov M. , Zayakin I. , Romanenko G. , Bogomyakov A. , Smirnova K. , Zaitsev K. , Fedin M. , Starikov A. , Shangin P. , Syroeshkin M. , Nasyrova D. , Tretyakov E.
Synthesis and Characterization of Free and Coordinated Nitroxide and Nitronyl Nitroxide Diradicals with a 2,7-Naphthalene Coupling Unit
Inorganic Chemistry. 2026. V.65. N12. P.6476–6491. DOI: 10.1021/acs.inorgchem.5c05421 OpenAlex

Published online:	Mar 16, 2026
Published print:	Mar 30, 2026

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