From a Dy(III) Single Molecule Magnet (SMM) to a Ferromagnetic [Mn(II)Dy(III)Mn(II)] Trinuclear Complex

The Schiff base compound 2,2′-{[(2-aminoethyl)­imino]­bis­[2,1-ethanediyl-nitriloethylidyne]}­bis-2-hydroxy-benzoic
acid (H4L) as a proligand was prepared in situ. This proligand has three potential coordination pockets which make
it possible to accommodate
from one to three metal ions allowing for the possible formation of
mono-, di-, and trinuclear complexes. Reaction of in situ prepared H4L with Dy­(NO3)3·5H2O resulted in the formation of a mononuclear complex [Dy­(H3L)2]­(NO3)·(EtOH)·8­(H2O) (1), which shows SMM behavior. In contrast, reaction
of in situ prepared H4L with Mn­(ClO4)2·6H2O and Dy­(NO3)3·5H2O in the presence of a base resulted in
a trinuclear mixed 3d–4f complex (NHEt3)2[Dy­{Mn­(L)}2]­(ClO4)·2­(H2O) (2). At low temperatures, compound 2 is a weak
ferromagnet. Thus, the SMM behavior of compound 1 can
be switched off by incorporating two Mn­(II) ions in close proximity
either side of the Dy­(III). This quenching behavior is ascribed to
the presence of the weak ferromagnetic interactions between the Mn­(II)
and Dy­(III) ions, which at T > 2 K act as a fluctuating
field causing the reversal of magnetization on the dysprosium ion.
Mass spectrometric ion signals related to compounds 1 and 2 were both detected in positive and negative ion
modes via electrospray ionization mass spectrometry. Hydrogen/deuterium
exchange (HDX) reactions with ND3 were performed in a FT-ICR
Penning-trap mass spectrometer.