NMR study on Ru-based quantum spin systems of [Ru(acac) 3 ] and [{Ru(acac) 2 } 2 ( μ -OEt) 2 ]

• Main Authors: Nakajima, S, Masuko, M, Oosawa, A, Goto, T, Hashimoto, T, Endo, A, Hayashita, T
• Format: Conference Proceeding
• Language: English
• Subjects: Acetylacetone; Bonding; Dimers; Electronegativity; Mathematical analysis; Monomers; Nuclear magnetic resonance; Ruthenium
• ISSN: 1742-6596; 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/302/1/012008

Tris( beta -diketonato)ruthenium(III) complexes of mononuclear [Ru(acac) sub(3)] and binuclear [{Ru(acac) sub(2)} sub(2)( mu -OEt) sub(2)] are spin-1/2 quantum spin magnets. In both system, Ru and surrounding O sub(6) atoms consist of octahedral geometry, and in the binuclear complex, two (acetylacetonato) ruthenium complexes are bridged by two oxygen atoms of ethoxyl groups, making up a dimer with Ru-Ru bond. The electronic state of ruthenium is easily controlled by changing the methyl groups on the acetylacetone to the different substituents such as electronegative trifluoromethyl group. We expect to introduce a new degree of freedom, a charge fluctuation into the dimer spin system. In this study, we investigate the spin state of monomer and dimer quantum spin systems by means of super(13)C, super(19)F, super(101)Ru-NMR at low temperatures. In the former [Ru(acac) sub(3)], we observed Curie-like temperature dependence in the Knight shift down to 1.5 K, indicating that the system was simply in the paramagnetic state. The dimer system [{Ru(acac) sub(2)} sub(2)( mu -OEt) sub(2)] on the other hand showed the NMR signal with very long T sub(1) at zero shift position at low temperatures, indicating that the system was the spin singlet state. In order to investigate the effect of substitution, we also report on results of mer-[Ru(ehfa) sub(3)] and [Ru(fhea) sub(3)], for which methyl groups are substituted by trifluoromethyl groups.