[Fe(bpym)(CN)₄]^-: A New Building Block for Designing Single-Chain Magnets

Abstract

We herein present the preparation, crystal structure, magnetic properties, and theoretical study of new heterobimetallic chains of formula {[Fe(III)(bpym)(CN4)]2M(II)(H2O)2}.6H2O [bpym = 2,2'-bipyrimidine; M = Zn (2), Co (3), Cu (4), and Mn (5)] which are obtained by using the building block PPh4[Fe(bpym)(CN)4].H2O (1) (PPh4+= tetraphenylphosphonium) as a ligand toward the fully solvated MII ions. The structure of complex 1 contains mononuclear [Fe(bpym)(CN)4]- anions. Compounds 2-5 are isostructural 4,2-ribbonlike bimetallic chains where the [Fe(bpym)(CN)4]- unit acts as a bis-monodenate ligand through two of its four cyanide ligands toward the M atom. Water hexamer clusters (4) and regular alternating fused six- and four-membered water rings with two dangling water molecules (2, 3, and 5) are trapped between the cyanide-bridged 4,2-ribbonlike chains. 1 and 2 behave as magnetically isolated low-spin iron(III) centers. 3 behaves as a single-chain magnet (SCM) with intrachain ferromagnetic coupling, slow magnetic relaxation, hysteresis effects, and frequency-dependent ac signals at T < 7 K). As expected for a thermally activated process, the nucleation field (Hn) in 3 increases with decreasing T and increasing v. Below 1.0 K, Hn becomes temperature independent but remains strongly sweep rate dependent. In this temperature range, the reversal of the magnetization may be induced by a quantum nucleation of a domain wall that then propagates due to the applied field. 4 and 5 are ferro- and ferrimagnetic chains respectively, with metamagnetic-like behavior (4). DFT-type calculations and QMC methodology provided a good understanding of the magnetic properties of 3-5.

Diverse Structures and Magnetism of Cobalt(II) and Manganese(II) Compounds with Mixed Azido and Carboxylato Bridges Induced by Methylpyridinium Carboxylates

“…These features may suggest the presence of weak interchain AFM interactions, which can exert the observed effect on the ac susceptibility at low temperature. [28] As in 3, the interchain magnetic coupling can be propagated through p-p interaction between the pyridine rings of adjacent chains. Here the pyridine and carboxylate groups are nearly coplanar.…”

Local spin dynamics at low temperature in the slowly relaxing molecular chain [Dy(hfac)3{NIT(C6H4OPh)}]: A μ+ spin relaxation study

“…1,9,11 The magnetic properties of such 1D systems were theoretically predicted by Glauber in the 1960s: 12 At low temperature, the magnetization relaxes slowly with a relaxation time that follows an Arrhenius law s ¼ s 0 Áexp(D/k B T), and no phase transition to threedimensional (3D) magnetic long-range order occurs before the magnetization blockage. 10,13 Subsequently, several other compounds were shown to exhibit SCM behavior, 11,[14][15][16][17][18][19][20][21] with quantum effects influencing the magnetization dynamics at low temperatures. 22 In particular, several works [23][24][25] showed that the requirements necessary to observe Glauber dynamics-a strong Ising-like anisotropy and a very low ratio of interchain/intrachain magnetic exchange interactions-are fulfilled in [Dy(hfac) 3 {NIT(C 6 H 4 OPh)}] (in short DyPhOPh).…”

Two binuclear cyanide-bridged Cr(III)-Mn(III) complexes based-on [Cr(2,2’-bipy)(CN)4]- building block: synthesis, crystal structures and magnetic properties

“…Furthermore, based-on the symmetry of the magnetic orbitals from the magnetic point of view, it is possible to predict the nature of the magnetic exchange between the cyanide-bridged paramagnetic metal ions by using simple orbital models. Therefore, up to now, a large amount of cyanide-bridged magnetic complexes with divers structures from 0D cluster to 3D network and interesting magnetic properties, such as highest T C molecule-based materials, moleculebased photomagnets, spin crossover materials, single-molecule magnets (SMMs), and single-chain magnets (SCMs), [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] have been successfully synthesized, structurally characterized and magnetically investigated.…”