{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,15]],"date-time":"2026-05-15T13:55:26Z","timestamp":1778853326296,"version":"3.51.4"},"reference-count":82,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2023,12,21]],"date-time":"2023-12-21T00:00:00Z","timestamp":1703116800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"JSPS","doi-asserted-by":"publisher","award":["22K19006"],"award-info":[{"award-number":["22K19006"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"JSPS","doi-asserted-by":"publisher","award":["JPMXP1222UE0016"],"award-info":[{"award-number":["JPMXP1222UE0016"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"name":"The Murata Science Foundation","award":["22K19006"],"award-info":[{"award-number":["22K19006"]}]},{"name":"The Murata Science Foundation","award":["JPMXP1222UE0016"],"award-info":[{"award-number":["JPMXP1222UE0016"]}]},{"name":"MEXT Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM)","award":["22K19006"],"award-info":[{"award-number":["22K19006"]}]},{"name":"MEXT Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM)","award":["JPMXP1222UE0016"],"award-info":[{"award-number":["JPMXP1222UE0016"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Ground triplet 4,6-bis(trifluoromethyl)-1,3-phenylene bis(tert-butyl nitroxide) (TF2PBN) reacted with [Y(hfac)3(H2O)2] (hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate), affording a doubly hydrogen-bonded adduct [Y(hfac)3(H2O)2(TF2PBN)]. The biradical was recovered from the adduct through recrystallization. Crystallographic analysis indicates that the torsion angles (|\u03b8| \u2264 90\u00b0) between the benzene ring and nitroxide groups were 74.9 and 84.8\u00b0 in the adduct, which are larger than those of the starting material TF2PBN. Steric congestion due to o-trifluoromethyl groups gives rise to the reduction of \u03c0-conjugation. Two hydrogen bonds enhance this deformation. Susceptometry of the adduct indicates a ground singlet with 2J\/kB = \u2212128(2) K, where 2J corresponds to the singlet\u2013triplet gap. The observed magneto-structure relation is qualitatively consistent with Rajca\u2019s pioneering work. A density functional theory calculation at the UB3LYP\/6-311+G(2d,p) level using the atomic coordinates determined provided a result of 2J\/kB = \u2212162.3 K for the adduct, whilst the corresponding calculation on intact TF2PBN provided +87.2 K. After a comparison among a few known compounds, the 2J vs. |\u03b8| plot shows a negative slope with a critical torsion of 65(3)\u00b0. The ferro- and antiferromagnetic coupling contributions are balanced in TF2PBN, being responsible for ground-state interconversion by means of small structural perturbation like hydrogen bonds.<\/jats:p>","DOI":"10.3390\/molecules29010070","type":"journal-article","created":{"date-parts":[[2023,12,22]],"date-time":"2023-12-22T01:19:42Z","timestamp":1703207982000},"page":"70","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["A Triplet\/Singlet Ground-State Switch via the Steric Inhibition of Conjugation in 4,6-Bis(trifluoromethyl)-1,3-phenylene Bisnitroxide"],"prefix":"10.3390","volume":"29","author":[{"given":"Nagito","family":"Haga","sequence":"first","affiliation":[{"name":"Department of Engineering Science, The University of Electro-Communications, Chofu 182-8585, Tokyo Prefecture, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9088-2526","authenticated-orcid":false,"given":"Takayuki","family":"Ishida","sequence":"additional","affiliation":[{"name":"Department of Engineering Science, The University of Electro-Communications, Chofu 182-8585, Tokyo Prefecture, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,12,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1016\/j.ccr.2014.10.012","article-title":"Radical ligand-containing single-molecule magnets","volume":"289","author":"Demir","year":"2015","journal-title":"Coord. Chem. Rev."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"392","DOI":"10.1021\/ar00167a004","article-title":"Toward molecular magnets: The metal-radical approach","volume":"22","author":"Caneschi","year":"1989","journal-title":"Acc. Chem. Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"626","DOI":"10.1021\/jacs.1c09815","article-title":"Electronic and Spintronic Open-Shell Macromolecules, Quo Vadis?","volume":"144","author":"Tan","year":"2022","journal-title":"J. Am. Chem. Soc."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/j.poly.2013.03.010","article-title":"What role has organic chemistry played in the development of molecule-based magnets?","volume":"66","author":"Iwamura","year":"2013","journal-title":"Polyhedron"},{"key":"ref_5","first-page":"179","article-title":"High-spin organic molecules and spin alignment in organic molecular assemblies","volume":"26","author":"Iwamura","year":"1990","journal-title":"Adv. Phys. Org. Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"644","DOI":"10.1038\/nchem.2547","article-title":"Dynamic molecular crystals with switchable physical properties","volume":"8","author":"Sato","year":"2016","journal-title":"Nat. Chem."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1039\/C1CS15165G","article-title":"Playing with organic radicals as building blocks for functional molecular materials","volume":"41","author":"Ratera","year":"2012","journal-title":"Chem. Soc. Rev."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2431","DOI":"10.1039\/D1TC04598A","article-title":"Recent progress in open-shell organic conjugated materials and their aggregated states","volume":"10","author":"Dong","year":"2022","journal-title":"J. Mater. Chem. C"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"803","DOI":"10.1039\/D0MH01391A","article-title":"Nitroxide radical polymers for emerging plastic energy storage and organic electronics: Fundamentals, materials, and applications","volume":"8","author":"Xie","year":"2021","journal-title":"Mater. Horiz."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"288","DOI":"10.1016\/j.chempr.2020.09.024","article-title":"Persistent and stable organic radicals: Design, synthesis, and applications","volume":"7","author":"Chen","year":"2021","journal-title":"Chem"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"11954","DOI":"10.1021\/acs.chemrev.3c00406","article-title":"From Stable Radicals to Thermally Robust High-Spin Diradicals and Triradicals","volume":"123","author":"Shu","year":"2023","journal-title":"Chem. Rev."},{"key":"ref_12","unstructured":"Rajca, A. (2021). Nitroxides: Synthesis, Properties and Applications, The Royal Society of Chemistry. Chapter 9."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"100379","DOI":"10.1016\/j.chphi.2023.100379","article-title":"Design of Magnetic Organic Molecules and Organic Magnets: Experiment, Theory and Computation with Application and Recent Advances","volume":"7","author":"Datta","year":"2023","journal-title":"Chem. Phys. Impact"},{"key":"ref_14","unstructured":"Baumgarten, M. (2012). EPR of Free Radicals in Solids II, Springer."},{"key":"ref_15","first-page":"1","article-title":"High spin organic molecules","volume":"Volume 4","author":"Baumgarten","year":"2018","journal-title":"World Scientific Reference on Spin in Organics"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1291","DOI":"10.1021\/jo502505r","article-title":"High-spin organic molecules","volume":"80","author":"Gallagher","year":"2015","journal-title":"J. Org. Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1258","DOI":"10.1002\/chem.202002234","article-title":"Molecular Magnets: The Synthesis and Characterization of High-Spin Nitrenes","volume":"27","author":"Chapyshev","year":"2021","journal-title":"Chem. Eur. J."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"19576","DOI":"10.1021\/jacs.2c09241","article-title":"High-spin S = 3\/2 ground-state aminyl triradicals: Toward high-spin oligo-aza nanographenes","volume":"144","author":"Zhang","year":"2022","journal-title":"J. Am. Chem. Soc."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e202301069","DOI":"10.1002\/chem.202301069","article-title":"Blatter diradicals with a spin coupler at the N(1) position","volume":"29","year":"2023","journal-title":"Chem. Eur. J."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"RCR5025","DOI":"10.1070\/RCR5025","article-title":"Conjugated nitroxides","volume":"91","author":"Tretyakov","year":"2022","journal-title":"Russ. Chem. Rev."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Zaytseva, E.V., and Mazhukin, D.G. (2021). Spirocyclic nitroxides as versatile tools in modern natural sciences: From synthesis to applications. Part I. Old and new synthetic approaches to spirocyclic nitroxyl radicals. Molecules, 26.","DOI":"10.3390\/molecules26030677"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Likhtenshtein, G.I. (2020). Nitroxides: Brief History, Fundamentals, and Recent Developments, Springer.","DOI":"10.1007\/978-3-030-34822-9"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1002\/cbic.201900291","article-title":"In-cell EPR: Progress towards structural studies inside cells","volume":"21","author":"Bonucci","year":"2020","journal-title":"ChemBioChem"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3686","DOI":"10.1246\/bcsj.55.3686","article-title":"Formation of Intramolecular Hydrogen Bond in Hydroxy-substituted Nitroxide Radicals as Evidenced by Electron Spin Resonance","volume":"55","author":"Kotake","year":"1982","journal-title":"Bull. Chem. Soc. Jpn."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1321","DOI":"10.1039\/b617142g","article-title":"What\u2019s new in stable radical chemistry?","volume":"5","author":"Hicks","year":"2007","journal-title":"Org. Biomol. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Kubo, T. (2019). Synthesis, physical properties, and reactivity of stable, \u03c0-conjugated, carbon-centered radicals. Molecules, 24.","DOI":"10.3390\/molecules24040665"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.cplett.2004.04.111","article-title":"Remarkably strong intermolecular antiferromagnetic couplings in the crystal of biphenyl-3,5-diyl bis(tert-butyl nitroxide)","volume":"392","author":"Kurokawa","year":"2004","journal-title":"Chem. Phys. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1008","DOI":"10.1143\/JPSJ.69.1008","article-title":"Singlet ground states in an organic S = 1\/2 spin ladder and a novel double spin chain of ferromagnetic dimers formed by an organic tetraradical","volume":"69","author":"Katoh","year":"2000","journal-title":"J. Phys. Soc. Jpn."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1002\/adma.19960080115","article-title":"Spontaneous magnetization in a 2:3 complex formed by 3,4\u2032,5-tris(N-oxy-tert-butylamino) biphenyl and manganese(II) bis(hexafluoroacetylacetonate)","volume":"8","author":"Iwamura","year":"1996","journal-title":"Adv. Mater."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1246\/cl.170933","article-title":"Unexpected Complexes of a [3+3] Cycloadduct from Biphenyl-3,5-diyl Bis(tert-butyl Nitroxide) with Gadolinium(III) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate","volume":"47","author":"Sekine","year":"2018","journal-title":"Chem. Lett."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Ito, S., Yoshitake, T., and Ishida, T. (2022). Ferromagnetic 2p-2p and 4f-2p Couplings in a Macrocycle from Two Biradicals and Two Gadolinium(III) Ions. Molecules, 27.","DOI":"10.3390\/molecules27154930"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Calder, A., and Forrester, A.R. (1967). The stability of aryl-t-butylnitroxides. Chem. Commun., 682\u2013684.","DOI":"10.1039\/c19670000682"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1080\/10587259708045080","article-title":"Exchange interactions in nitroxide biradicals","volume":"305","author":"Chiarelli","year":"1997","journal-title":"Mol. Cryst. Liq. Cryst."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1062","DOI":"10.1246\/cl.200413","article-title":"Practically Diamagnetic Macrocycle Consisting of Nickel-Biradical Heterospins with the Largest Out-of-Plane Torsion at Coordination Bonds","volume":"49","author":"Ito","year":"2020","journal-title":"Chem. Lett."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"10619","DOI":"10.1021\/acs.inorgchem.2c01107","article-title":"Rare-Earth (RE = Y, Gd, Tb, Dy, Ho, and Er) Chains Bridged with a Triplet Biradical and Magnetic Hysteresis Recorded for RE = Tb","volume":"61","author":"Ito","year":"2022","journal-title":"Inorg. Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1249","DOI":"10.1039\/a901906e","article-title":"Singlet\u2013triplet bistability in a 1,3-phenylene-based bis(aminoxyl) diradical","volume":"13","author":"Rajca","year":"1999","journal-title":"Chem. Commun."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1669","DOI":"10.1016\/S0277-5387(01)00671-4","article-title":"4,6-Bis(trifluoromethyl)-N,N\u2032-di-tert-butyl-1,3-phenylenebis(aminoxyl) and its bis(hexafluoroacetylacetonato)manganese(II) complex: Synthesis, X-ray crystallography, and magnetism","volume":"20","author":"Rajca","year":"2001","journal-title":"Polyhedron"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1275","DOI":"10.1016\/0022-1902(68)80557-3","article-title":"Rare-earth trishexafluoroacetylacetonates and related compounds","volume":"30","author":"Richardson","year":"1968","journal-title":"J. Inorg. Nucl. Chem."},{"key":"ref_39","unstructured":"(2021). CrysAlisPRO, Oxford Diffraction\/Agilent Technologies UK Ltd."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1107\/S0021889808042726","article-title":"Olex2: A complete structure solution, refinement and analysis program","volume":"42","author":"Dolomanov","year":"2009","journal-title":"J. Appl. Crystallogr."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1107\/S2053229614024218","article-title":"Crystal structure refinement with SHELXL","volume":"71","author":"Sheldrick","year":"2015","journal-title":"Acta Crystallogr. Sect. C Struct. Chem."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"532","DOI":"10.1021\/ed085p532","article-title":"Diamagnetic corrections and Pascal\u2019s constants","volume":"85","author":"Bain","year":"2008","journal-title":"J. Chem. Educ."},{"key":"ref_43","unstructured":"Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Petersson, G.A., and Nakatsuji, H. (2019). Gaussian 16, Revision C.01, Gaussian, Inc."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"526","DOI":"10.1016\/j.ccr.2008.05.014","article-title":"Prediction of molecular properties and molecular spectroscopy with density functional theory: From fundamental theory to exchange-coupling","volume":"253","author":"Neese","year":"2009","journal-title":"Coord. Chem. Rev."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"4903","DOI":"10.1063\/1.437369","article-title":"The X\u03b1 valence bond theory of weak electronic coupling. Application to the low-lying states of Mo2Cl84\u2212","volume":"70","author":"Noodleman","year":"1979","journal-title":"J. Chem. Phys."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"5737","DOI":"10.1063\/1.440939","article-title":"Valence bond description of antiferromagnetic coupling in transition metal dimers","volume":"74","author":"Noodleman","year":"1981","journal-title":"J. Chem. Phys."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/0379-6779(87)90335-3","article-title":"A generalized MO (GMO) approach to unstable molecules with quasi-degenerate electronic states: Ab initio GMO calculations of intramolecular effective exchange integrals and designing of organic magnetic polymers","volume":"19","author":"Yamaguchi","year":"1987","journal-title":"Synth. Met."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1016\/S0009-2614(00)00166-4","article-title":"Ab initio computations of effective exchange integrals for H\u2013H, H\u2013He\u2013H and Mn2O2 complex: Comparison of broken-symmetry approaches","volume":"319","author":"Soda","year":"2000","journal-title":"Chem. Phys. Lett."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"6480","DOI":"10.1021\/ja01629a013","article-title":"Stretching frequencies as a function of distances in hydrogen bonds","volume":"77","author":"Nakamoto","year":"1955","journal-title":"J. Am. Chem. Soc."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Ishida, T., Ito, S., Homma, Y., and Kyoden, Y. (2021). Molecular S = 2 High-Spin, S = 0 Low-Spin and S = 0 \u21c4 2 Spin-Transition\/-Crossover Nickel(II)-Bis(nitroxide) Coordination Compounds. Inorganics, 9.","DOI":"10.3390\/inorganics9020010"},{"key":"ref_51","unstructured":"Lluncll, M., Casanova, D., Circra, J., Bofill, J.M., Alcmany, P., Alvarez, S., Pinsky, M., and Avnir, D. (2005). SHAPE, Version 2.1, Hebrew University of Jerusalem."},{"key":"ref_52","first-page":"231","article-title":"Synthesis and Characterization of Holmium Complexes Containing \u03b2-Diketonate Ligands","volume":"19","author":"Lee","year":"1998","journal-title":"Bull. Korean Chem. Soc."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"24476","DOI":"10.1021\/jp0654462","article-title":"Quenching of IR Luminiescence of Erbium, Neodymium and Ytterbium \u03b2-diketonate Complexes by Ligand C-H and C-D bonds","volume":"110","author":"Tan","year":"2006","journal-title":"J. Phys. Chem. B"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"751","DOI":"10.1107\/S0567739476001551","article-title":"Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides","volume":"32","author":"Shannon","year":"1976","journal-title":"Acta Crystallogr. Sect. A Cryst. Phys. Diffr. Theor. Gen. Crystallogr."},{"key":"ref_55","first-page":"451","article-title":"Anomalous paramagnetism of copper acetate","volume":"214","author":"Bleaney","year":"1952","journal-title":"Proc. Royal Soc. Ser. A"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.poly.2014.11.035","article-title":"Strong exchange couplings in lanthanide complexes with an aliphatic nitroxide radical 1,1,3,3-tetramethylisoindolin-2-oxyl","volume":"87","author":"Nakamura","year":"2015","journal-title":"Polyhedron"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"5893","DOI":"10.1039\/C3DT53586J","article-title":"Doubly TEMPO-coordinated gadolinium(III), lanthanum(III), and yttrium(III) complexes. Strong superexchange coupling across rare earth ions","volume":"43","author":"Murakami","year":"2014","journal-title":"Dalton Trans."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/S0301-0104(99)00090-7","article-title":"Reverting the effect of magnetic couplers in bridged di-and polyradicals","volume":"244","author":"Baumgarten","year":"1999","journal-title":"Chem. Phys."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"14513","DOI":"10.1021\/ja3050579","article-title":"Stable Tetrabenzo-Chichibabin\u2019s Hydrocarbons: Tunable Ground State and Unusual Transition between Their Closed-Shell and Open-Shell Resonance Forms","volume":"134","author":"Zeng","year":"2012","journal-title":"J. Am. Chem. Soc."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"e3965","DOI":"10.1002\/poc.3965","article-title":"The quest for a triplet ground-state alkene: Highly twisted C=C double bonds","volume":"32","author":"Wu","year":"2019","journal-title":"J. Phys. Org. Chem."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"e202205729","DOI":"10.1002\/anie.202205729","article-title":"Synthesis and Isolation of a Kekul\u00e9 Hydrocarbon with a Triplet Ground State","volume":"61","author":"Shimizu","year":"2022","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"3602","DOI":"10.1021\/cm061222k","article-title":"Bistable Polymorphs Showing Diamagnetic and Paramagnetic States of an Organic Crystalline Biradical Biphenyl-3,5-diyl Bis(tert-butylnitroxide)","volume":"18","author":"Nishimaki","year":"2006","journal-title":"Chem. Mater."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"9598","DOI":"10.1021\/ja102890g","article-title":"Organic two-step spin-transition-like behavior in a linear S = 1 array: 3\u2019-methylbiphenyl-3,5-diyl bis(tert-butylnitroxide) and related compounds","volume":"132","author":"Nishimaki","year":"2010","journal-title":"J. Am. Chem. Soc."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"7813","DOI":"10.1039\/C5TC00668F","article-title":"Intermediate-paramagnetic phases with a half and a quarter spin entities in fluorinated biphenyl-3,5-diyl bis(tert-butyl nitroxides)","volume":"3","author":"Konno","year":"2015","journal-title":"J. Mater. Chem. C"},{"key":"ref_65","doi-asserted-by":"crossref","unstructured":"Yoshitake, T., Kudo, H., and Ishida, T. (2016). Thermally Activated Paramagnets from Diamagnetic Polymers of Biphenyl-3,5-diyl Bis(tert-butyl Nitroxides) with Methyl and Fluoro Groups at the 2\u2019- and 5\u2019-Positions. Crystals, 6.","DOI":"10.3390\/cryst6030030"},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"847","DOI":"10.1021\/ja00056a003","article-title":"4,6-Dimethoxy-1,3-phenylenebis(N-tert-butyl nitroxide) with a singlet ground state. Formal violation of a rule that m-phenylene serves as a robust ferromagnetic coupling unit","volume":"115","author":"Kanno","year":"1993","journal-title":"J. Am. Chem. Soc."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"9347","DOI":"10.1021\/ja961849b","article-title":"Antiferromagnetic exchange interaction among the three spins placed in an isosceles triangular configuration in 2,4-dimethoxy-1,3,5-benzenetriyltris(N-tert-butyl nitroxide)","volume":"118","author":"Fujita","year":"1996","journal-title":"J. Am. Chem. Soc."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1002\/anie.199201801","article-title":"Stable N,N\u2032-Di-tert-butyl-meta-phenylene-bisnitroxides\u2014Unexpected Ground-State Singlets","volume":"31","author":"Dvolaitzky","year":"1992","journal-title":"Angew. Chem. Int. Ed. Engl."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"3443","DOI":"10.1246\/bcsj.69.3443","article-title":"Through-bond and through-space interactions of organic radicals coupled by m-phenylene","volume":"69","author":"Yoshizawa","year":"1996","journal-title":"Bull. Chem. Soc. Jpn."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"6727","DOI":"10.1021\/ja00130a012","article-title":"Ab initio calculations show why m-phenylene is not always a ferromagnetic coupler","volume":"117","author":"Fang","year":"1995","journal-title":"J. Am. Chem. Soc."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"699","DOI":"10.1021\/ct100602y","article-title":"An integrated protocol for the accurate calculation of magnetic interactions in organic magnets","volume":"7","author":"Barone","year":"2011","journal-title":"J. Chem. Theory Comput."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"1958","DOI":"10.1021\/ct400020x","article-title":"Conformational effects on the magnetic properties of an organic diradical: A computational study","volume":"9","author":"Barone","year":"2013","journal-title":"J. Chem. Theory Comput."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"904","DOI":"10.1038\/nature05037","article-title":"Dependence of single-molecule junction conductance on molecular conformation","volume":"442","author":"Venkataraman","year":"2006","journal-title":"Nature"},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"8886","DOI":"10.1002\/anie.200903946","article-title":"Chemically controlled conductivity: Torsion-angle dependence in a single-molecule biphenyldithiol junction","volume":"48","author":"Vonlanthen","year":"2009","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"530","DOI":"10.1246\/cl.131115","article-title":"Theoretical investigation of the dependence of exchange interaction on dihedral angle between two aromatic rings in a wire unit","volume":"43","author":"Nishizawa","year":"2014","journal-title":"Chem. Lett."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"15150","DOI":"10.1021\/jp9053346","article-title":"Monti and G. Prampolini, Magnetic Interactions in Phenyl-Bridged Nitroxide Diradicals: Conformational Effects by Multireference and Broken Symmetry DFT Approaches","volume":"113","author":"Barone","year":"2009","journal-title":"J. Phys. Chem. A"},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"15426","DOI":"10.1021\/ja037787o","article-title":"Mechanisms of exchange modulation in trimethylenemethane-type biradicals: The roles of conformation and spin density","volume":"125","author":"Shultz","year":"2003","journal-title":"J. Am. Chem. Soc."},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"11761","DOI":"10.1021\/ja0367849","article-title":"Trends in exchange coupling for trimethylenemethane-type bis(semiquinone) biradicals and correlation of magnetic exchange with mixed valency for cross-conjugated systems","volume":"125","author":"Shultz","year":"2003","journal-title":"J. Am. Chem. Soc."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"2870","DOI":"10.1021\/ja00901a059","article-title":"Vicinal proton coupling in nuclear magnetic resonance","volume":"85","author":"Karplus","year":"1963","journal-title":"J. Am. Chem. Soc."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"1535","DOI":"10.1063\/1.1730955","article-title":"Radiation damage in organic crystals. II. Electron spin resonance of (CO2H)CH2CH(CO2H) in \u03b2-succinic acid","volume":"32","author":"Heller","year":"1960","journal-title":"J. Chem. Phys."},{"key":"ref_81","unstructured":"Kahn, O. (1993). Molecular Magnetism, VCH."},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"7443","DOI":"10.1021\/acs.jpca.3c03265","article-title":"Hydrogen-Bonding-Assisted Substituent Engineering for Modulating Magnetic Spin Couplings and Switching in m-Phenylene Nitroxide Diradicals","volume":"127","author":"Zheng","year":"2023","journal-title":"J. Phys. Chem. 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