126494 20240319081007.0 doi 10.1021/jacs.2c05453 sideral 130311 ART-2022-130311 eng Rubín, J. Universidad de Zaragoza (orcid)0000-0003-1029-3751 Origin of the unusual ground-state spin S = 9 in a Cr10single-molecule magnet 2022 Access copy available to the general public Unrestricted The molecular wheel Cr10(OMe)20(O2CCMe3)10], abbreviated {Cr10}, with an unusual intermediate total spin S = 9 and non-negligible cluster anisotropy, D/kB= -0.045(2) K, is a rare case among wheels based on an even number of 3d-metals, which usually present an antiferromagnetic (AF) ground state (S = 0). Herein, we unveil the origin of such a behavior. Angular magnetometry measurements performed on a single crystal confirmed the axial anisotropic behavior of {Cr10}. For powder samples, the temperature dependence of the susceptibility plotted as ¿T(T) showed an overall ferromagnetic (FM) behavior down to 1.8 K, whereas the magnetization curve M(H) did not saturate at the expected 30 µB/fu for 10 FM coupled 3/2 spin Cr3+ions, but to a much lower value, corresponding to S = 9. In addition, the X-ray magnetic circular dichroism (XMCD) measured at high magnetic field (170 kOe) and 7.5 K showed the polarization of the cluster moment up to 23 µB/fu. The magnetic results can be rationalized within a model, including the cluster anisotropy, in which the {Cr10} wheel is formed by two semiwheels, each with four Cr3+spins FM coupled (JFM/kB= 2.0 K), separated by two Cr3+ions AF coupled asymmetrically (J23/kB= J78/kB= -2.0 K; J34/kB= J89/kB= -0.25 K). Inelastic neutron scattering and heat capacity allowed us to confirm this model leading to the S = 9 ground state and first excited S = 8. Single-molecule magnet behavior with an activation energy of U/kB= 4.0(5) K in the absence of applied field was observed through ac susceptibility measurements down to 0.1 K. The intriguing magnetic behavior of {Cr10} arises from the detailed asymmetry in the molecule interactions produced by small-angle distortions in the angles of the Cr-O-Cr alkoxy bridges coupling the Cr3+ions, as demonstrated by ab initio and density functional theory calculations, while the cluster anisotropy can be correlated to the single-ion anisotropies calculated for each Cr3+ion in the wheel. info:eu-repo/grantAgreement/ES/DGA/E12-20R info:eu-repo/grantAgreement/ES/AEI/PID2020-115159GB-I00/AEI/10.13039/501100011033 info:eu-repo/grantAgreement/ES/MINECO/MAT2017-83468-R info:eu-repo/semantics/openAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 15.0 2022 CHEMISTRY, MULTIDISCIPLINARY 17 / 178 = 0.096 2022 Q1 T1 5.945 2022 Biochemistry 2022 Q1 Colloid and Surface Chemistry 2022 Q1 Chemistry (miscellaneous) 2022 Q1 Catalysis 2022 Q1 25.7 2022 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Arauzo, A. Universidad de Zaragoza (orcid)0000-0002-5999-341X Bartolomé, E. Sedona, F. Rancan, M. Armelao, L. Luzón, J. (orcid)0000-0002-9208-0807 Guidi, T. Wilhelm, F. Rogalev, A. Amann, A. Spagna, S. Bartolomé, J. Universidad de Zaragoza (orcid)0000-0002-6517-1236 Bartolomé, F. (orcid)0000-0002-0047-1772 5001 065 Universidad de Zaragoza Dpto. Ciencia Tecnol.Mater.Fl. Área Cienc.Mater. Ingen.Metal. 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 144, 27 (2022), 12520-12535 J. Am. Chem. Soc. Journal of the American Chemical Society 0002-7863 2954848 http://zaguan.unizar.es/record/126494/files/texto_completo.pdf Postprint 1018760 http://zaguan.unizar.es/record/126494/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:126494 articulos driver 2024-03-18-14:43:43 ARTICLE