A new family of [CuIILnIIIMV] heterotrimetallic complexes (Ln = La, Gd, Tb; M = Mo, W): model systems to probe exchange interactions and single-molecule magnet properties

Author(s): Diana Visinescu ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Maria-Gabriela Alexandru ⁶ ^, ⁷ ^, ⁸ ^, ⁹ ^, ⁵ , Augustin M. Madalan ⁶ ^, ⁷ ^, ⁸ ^, ⁹ ^, ⁵ , Ie-Rang Jeon ¹⁰ ^, ¹¹ ^, ¹² ^, ¹³ ^, ¹⁴ , Corine Mathonière ¹⁰ ^, ¹⁵ ^, ¹⁶ ^, ¹³ ^, ¹⁴ , Rodolphe Clérac ¹⁰ ^, ¹¹ ^, ¹² ^, ¹³ ^, ¹⁴ , Marius Andruh ⁶ ^, ⁷ ^, ⁸ ^, ⁹ ^, ⁵

Publication date (Electronic): 2016

Journal: Dalton Transactions

Publisher: Royal Society of Chemistry (RSC)

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Abstract

Four 3d–4f–4(5)d heterotrimetallic complexes, [L ²CuLn(H ₂O) ₅( μ-NC)M(CN) ₇], were obtained from the association of the binuclear 3d–4f complexes and {M ^V(CN) ₈} ³⁻ metalloligands.

Abstract

Four isostructural trinuclear 3d–4f–4(5)d heterotrimetallic complexes, with the general formula [L ²CuLn(H ₂O) ₅(μ-NC)M(CN) ₇], were obtained from the association of binuclear 3d–4f complexes and {M ^V(CN) ₈} ³⁻ metalloligands (M = Mo, Ln = La 1; M = W, Ln = La 2; M = Mo, Ln = Gd 3; M = Mo; Ln = Tb 4, where H ₂L ² = 1,2-ethanediylbis(2-iminomethylene-6-methoxy-phenol)). The metalloligand coordinates through a single-cyanido group at the apical position of the copper( ii) ion belonging to the {Cu ^IILn ^III} binuclear complex. The analysis of the magnetic data for the La( iii) derivatives (compounds 1 and 2), in the 1.85–300 K temperature range, shows a weak ferromagnetic exchange interaction between Cu ^II and Mo ^V/W ^V ions across the cyanido bridge ( J _CuM/ k _B = 3.6(6) K; g = 2.23(5) for 1 and J _CuM/ k _B = 3.8(6) K, g = 2.21(5) for 2, with H = −2 J _CuM S _Cu· S _M). These results were used to simulate the magnetic properties of compound 3, using the isotropic spin Hamiltonian H = −2 J _CuMo S _Cu· S _Mo − 2 J _CuGd S _Cu· S _Gd. The resulting magnetic interaction between Cu ^II and Gd ^III ions via the phenoxo-bridge was found to be weakly ferromagnetic ( J _CuGd/ k _B = +4.5(2) K with J _CuMo/ k _B = +3.6(2) K, g _Gd = g _Cu = 2.00 and g _Mo = 1.98). The dc magnetic properties for compound 4 also show a predominant ferromagnetic interaction, while the ac magnetic measurements indicate the presence of the slow relaxation of the magnetization below 3.5 K.