Intramolecular Spin State Locking in Iron(II) 2,6-Di(pyrazol-3-yl)pyridine Complexes by Phenyl Groups: An Experimental Study
by
Yulia Nelyubina 1,2,*, Alexander Polezhaev 1,3, Alexander Pavlov 1, Dmitrii Aleshin 1,4, Svetlana Savkina 1, Nikolay Efimov 2
, Teimur Aliev 1 and Valentin Novikov 1,*
Yulia Nelyubina 1,2,*, Alexander Polezhaev 1,3, Alexander Pavlov 1, Dmitrii Aleshin 1,4, Svetlana Savkina 1, Nikolay Efimov 2, Teimur Aliev 1 and Valentin Novikov 1,*
1
A.N. Nesmeyanov Institute of Organoelement Compounds, Vavilova Str. 28, 119991 Moscow, Russia
2
Kurnakov Institute of General and Inorganic Chemistry, Leninsky prosp. 31, 119991 Moscow, Russia
3
Bauman Moscow State Technical University, 2nd Baumanskaya Str. 5, 105005 Moscow, Russia
4
Lomonosov Moscow State University, Leninskiye Gory, 1, 119991 Moscow, Russia
*
Authors to whom correspondence should be addressed.
Magnetochemistry 2018, 4(4), 46; https://doi.org/10.3390/magnetochemistry4040046
Received: 14 September 2018 / Revised: 28 September 2018 / Accepted: 10 October 2018 / Published: 16 October 2018
(This article belongs to the Special Issue Controlling Molecular Nanomagnets)
Here we report a series of 1-phenyl-5-substituted 2,6-di(pyrazol-3-yl)pyridine complexes with iron(II) ion found in a high spin state in solids (according to magnetochemistry) and in solution (according to NMR spectroscopy), providing experimental evidence for it being an intramolecular effect induced by the phenyl groups. According to X-ray diffraction, the high spin locking of the metal ion is a result of its highly distorted coordination environment (with a very low ‘twist’ angle atypical of 2,6-di(pyrazol-3-yl)pyridine complexes), which remains this way in complexes with different substituents and counterions, in a diamagnetic zinc(II) analogue and in their solutions. Three possible reasons behind it, including additional coordination with the phenyl group, energy penalty incurred by its rotation or intramolecular stacking interactions, are addressed experimentally.
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Keywords:
high-spin complexes; iron(II) complexes; molecular design; spin-crossover; spin state trapping; paramagnetic NMR spectroscopy
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MDPI and ACS Style
Nelyubina, Y.; Polezhaev, A.; Pavlov, A.; Aleshin, D.; Savkina, S.; Efimov, N.; Aliev, T.; Novikov, V. Intramolecular Spin State Locking in Iron(II) 2,6-Di(pyrazol-3-yl)pyridine Complexes by Phenyl Groups: An Experimental Study. Magnetochemistry 2018, 4, 46.
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