Ferromagnetic Spin-Coupling between Gadolinium(III) and Copper(II) Ions in Discrete Binuclear Gd(III)–Cu(II) Complexes

Abstract

Three discrete binuclear gadolinium(III)–copper(II) complexes (CuGd(fsadien)NO3·5H2O (1), CuGd(hsapn)NO3·3H2O (2), and [Gd(pvm)3Cu(A)] (3)) have been synthesized; we use the notation H4fsadien=N,N′-bis(3-carboxysalicylidene)diethylenetriamine, H4hsapn=N,N′-bis(3-hydroxysalicylidene)-1,2-propanediamine, Hpvm=dipivaloylmethane (2,2,6,6-tetramethyl-3,5-heptanedione), and H2A=4-(6-methyl-8-oxo-2,5-diazanona-1,5,7-trienyl)imidazole. Magnetic susceptibility measurements (4.2–300 K) have revealed that the spin coupling between the Gd(III) and Cu(II) ions is ferromagnetic with coupling constants J=+2.3 cm−1 for (1), +5.7 cm−1 for (2), and +0.5cm −1 for (3), on the basis of the spin-Hamiltonian H=−2JSGd·SCu.

Magnetic lanthanide–transition-metal organic–inorganic hybrid materials: From discrete clusters to extended frameworks

“…The Cu· · ·Cu contacts are invariant while the polyhedral angles deviate from 60 • required for a perfect cuboctahedron. Surprisingly, if betaine ligands (either pyridinioacetate or pyridiniopropionate) are used, a similar Cu 12 Ln 6 ( 3 -OH) 24 (Ln = Y, Nd, Sm, Gd) cage, in which the cuboctahedron of copper centers remains unchanged from that of Cu 12 Ln 8 ( 3 -OH) 24 core, can be isolated [61]. Rather than being coated in a Ln 8 cube, herein it is coated in a Ln 6 octahedron.…”

“…According to Hund's rule, the latter will be lower in energy and hence the excited state of the system favors ferromagnetic exchange. After this pioneering work, many systems containing 4f-3d pairs of interacting ions were synthesized [24][25][26][27][28]. As to the exchange mechanism, most of the work focused on the nature of magnetic coupling involving Gd 3+ , while that involving other lanthanide ions with large magnetic anisotropy is still not revealed mainly due to the unquenched orbital contribution which introduces many complications [13a].…”

Formation of Charge-Transfer Complexes from Neutral Bis(porphyrin) Sandwiches

“…Similar results have been obtained by Gatteschi and Rey with a discrete complex in which a Gd(III) center is coordinated by two nitronylnitroxide ligands: this three-spin system exhibits weak ferromagnetic coupling between the S ) 7 / 2 gadolinium(III) center and the S ) 1 / 2 radicals. 30 The ferromagnetic nature of the Gd(III)-Cu(II) pair in three binuclear Gd(III)-Cu(II) complexes was later confirmed by Matsumoto et al 31 A general interpretation [in terms of the contraction of the 4f magnetic orbitals of the Gd(III) center] of what appears to be a general phenomenon has been offered by Kahn and Guillou. 32 Similar to the above results, in Gd(OETAP) 2 , the interaction between the S ) 7 / 2 Gd(III) center and the S ) 1 / 2 porphyrin π-radical is ferromagnetic in nature.…”

“…[29][30][31][32] In these compounds, the S ) 1 / 2 spin is either a Cu(II) ion or a delocalized nitroxide-type ligand. The question that has been addressed in these studies is the nature of the magnetic interaction between the two spins: is it ferromagnetic or antiferromagnetic?…”

Synthesis, Structure, and Magnetism of Heterobinuclear Complex GdCu(OTf)3(bdmap)2(H2O)·THF

“…Thus, intermolecular interactions can be neglected. The spin Hamiltonian H = -2JSGd • SCu has been used to derive the susceptibility equation [14,15]:…”