Heterometallic trinuclear {CoLn} (Ln = Gd, Tb, Ho and Er) complexes in a bent geometry. Field-induced single-ion magnetic behavior of the Er and Tb analogues

• Published in: Dalton transactions : an international journal of inorganic chemistry 2016-05, Vol.45 (22), p.9235-9249
• Main Authors: Goura, Joydeb, Brambleby, Jamie, Topping, Craig V, Goddard, Paul A, Suriya Narayanan, Ramakirushnan, Bar, Arun Kumar, Chandrasekhar, Vadapalli
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt03871e

Through the use of a multi-site compartmental ligand, 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}methyl]phenol (LH 3 ), the family of heterometallic, trinuclear complexes of the formula [Co III 2 Ln(L) 2 (μ-O 2 CCH 3 ) 2 (H 2 O) 3 ]·NO 3 · x MeOH· y H 2 O has been expanded beyond Ln = Dy III to include Gd III ( 1 ), Tb III ( 2 ), Ho III ( 3 ) and Er III ( 4 ) for 1 , 3 and 4 ( x = 1; y = 1) and for 2 ( x = 0; y = 2). The metallic core of these complexes consists of a (Co III -Ln III -Co III ) motif bridged in a bent geometry resulting in six-coordinated distorted Co III octahedra and nine-coordinated Ln III monocapped square-antiprisms. The magnetic characterization of these compounds reveals the erbium and terbium analogues to display a field induced single-ion magnetic behavior similar to the dysprosium analogue but at lower temperatures. The energy barrier for the reversal of the magnetization of the Co III 2 Tb III analogue is U eff ≥ 15.6(4) K, while for the Co III 2 Er III analogue U eff ≥ 9.9(8) K. The magnetic properties are discussed in terms of distortions of the 4f electron cloud. In this paper we report the synthesis, structures and detailed magnetic properties of heterometallic trinuclear Co III Ln III complexes.