Experimental and Theoretical Investigation of the Anti-Ferromagnetic Coupling of CrIII Ions through Diamagnetic −O–NbV–O– Bridges

Jurić, Marijana; Androš Dubraja, Lidija; Pajić, Damir; Torić, Filip; Zorko, Andrej; Ozarowski, Andrew; Despoja, Vito; Lafargue-Dit-Hauret, William; Rocquefelte, Xavier (2017) Experimental and Theoretical Investigation of the Anti-Ferromagnetic Coupling of CrIII Ions through Diamagnetic −O–NbV–O– Bridges. Inorganic Chemistry, 56 (12). pp. 6879-6889. ISSN 0020-1669

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Abstract

The synthesis and properties of a novel hetero-tetranuclear compound [Cr2(bpy)4(μ-O)4Nb2(C2O4)4]·3H2O (1 ; bpy = 2, 2′-bipyridine), investigated by single-crystal X-ray diffraction, magnetization measurements, IR, UV/visible spectroscopy, electron paramagnetic resonance (EPR ; X- and Q-bands and high-field), and density functional theory (DFT) calculations, are reported. Crystal structure of 1 (orthorhombic Pcab space group) consists of a square-shaped macrocyclic {; ; ; ; ; Cr2(μ-O)4Nb2}; ; ; ; ; core in which CrIII and NbV ions are alternately bridged by oxo ions and three uncoordinated water molecules. The intramolecular CrIII···CrIII distances through the −O–NbV–O– bridges are 7.410(2) and 7.419(2) Å, while diagonal separation is 5.406(2) Å. The temperature dependence of magnetization M(T) evidences an anti-ferromagnetic ground state, which originates from a magnetic interaction between two CrIII ions of spin 3/2 through two triatomic −O–NbV–O– diamagnetic bridges. A spin Hamiltonian appropriate for polynuclear isolated magnetic units was used. The best-fitting curve for this model is obtained with the parameters gCr = 1.992(3), J = −12.77(5) cm–1, and |D| = 0.17(4) cm–1. The CrIII···CrIII dimer model is confirmed by EPR spectra, which exhibit a pronounced change of their shape around the temperature corresponding to the intradimer coupling J. The EPR spectra simulations and DFT calculations reveal the presence of a single-ion anisotropy that is close to being uniaxial, D = −0.31 cm–1 and E = 0.024 cm–1.

Item Type:	Article
Additional Information:	This work has been supported by the Croatian Science Foundation under Project Nos. IP-2014-09-4079 and UIP-2014-09-8276. A.Z. acknowledges the financial support of the Slovenian Research Agency through the Program No. P1-0125 and the Project No. Bi-US/14-15-039. National High Magnetic Field Laboratory is supported by the NSF through the Cooperative Agreement DMR-1157490, the State of Florida, and the Department of Energy. X.R. and W.L.D.H. thank CCIPL (Nantes) computing centre for computational facilities.
Uncontrolled Keywords:	Oxo-Bridged Complexes ; Chromium ; Niobium ; Magnetic Properties ; DFT Calculation
Subjects:	NATURAL SCIENCES > Physics
Divisions:	Division of Materials Chemistry
Projects:	Project title Project leader Project code Project type Novi metal-organsi sustavi s oksalatnim i kinoidnim ligandima s podešenim svojstvima pogodnim za primjenu-NMOSBOQLWTPSFP Krešimir Molčanov IP-2014-09-4079 HRZZ Multiferični i magnetoelektrični sustavi-FerMaEl Damir Pajić UIP-2014-09-8276 HRZZ
Depositing User:	Marijana Jurić
Date Deposited:	04 May 2020 07:40
URI:	http://fulir.irb.hr/id/eprint/5648
DOI:	10.1021/acs.inorgchem.7b00181

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