[ReCl₄(CN)₂]²⁻: A High Magnetic Anisotropy Building Unit Giving Rise to the Single-Chain Magnets (DMF)₄MReCl₄(CN)₂ (M = Mn, Fe, Co, Ni)

Abstract

An S = 3/2, high-anisotropy building unit, trans-[ReCl(4)(CN)(2)](2-), representing the first paramagnetic complex with a mixture of just cyanide and halide ligands, has been synthesized through the reaction of (Bu(4)N)CN with ReCl(4)(THF)(2). This species is characterized in detail and employed in directing the formation of a series of one-dimensional coordination solids of formula (DMF)(4)MReCl(4)(CN)(2) (M = Mn (2), Fe (3), Co (4), Ni (5)). Variable-temperature dc magnetic susceptibility measurements demonstrate the presence of intrachain antiferromagnetic (2) and ferromagnetic (3-5) exchange coupling within these solids. In addition, probing the ac magnetic susceptibility as a function of both temperature and frequency reveals that all of the chain compounds exhibit slow relaxation of the magnetization. The relaxation time is shown to be thermally activated, with energy barriers to relaxation of Delta(tau) = 31, 56, 17, and 20 cm(-1) for 2-5, respectively. Notably, the field-dependent magnetization of the iron congener exhibits a significant hysteresis effect at low temperature, with a coercive field of H(C) = 1.0 T, thus demonstrating magnetlike behavior in this one-dimensional system. Finally, the magnetization dynamics of all solids occur within the finite-size regime, where the magnetic domain growth is limited due to physical defects along the chains within the crystals.

Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

“…This was further confirmed by the anisotropic behavior of 85, where the octahedral coordination sphere incorporates four Cl atoms in equatorial positions and two CN ligands in axial positions (Fig. 27), and the D parameter was determined to be −14.4 cm -1 [170]. Furthermore, a smaller D parameter (19 cm -1 ) was observed for the higher symmetric complex 86 compared with its less symmetric congener 87 (D = 37 cm -1 ) [158].…”

One‐Dimensional End‐To‐End Azide‐Bridged MnIII Complexes Incorporating Alkali Metal Ions: Slow Magnetic Relaxations and Metamagnetism

“…[1] To attain one-dimensional (1D) entities exhibiting a slow magnetic relaxation, much effort has been devoted to promoting Ising-type magnetic anisotropy in materials of interest. A great number of SCMs constructed from 3d, [2] 3d-radical, [3] 3d-3d, [4] 3d-5d, [5] 3d-4f, [6] and 4f-radical [7] systems have been explored so far. To facilitate slow magnetic relaxation in molecular solids, it was generally believed that interchain magnetic interactions should be trivial compared to intrachain couplings.…”

Two cyanide-bridged compounds composed of Schiff base–manganese(III) building block with dicyanamido and hexacyanocobaltate(III) as ligands: Crystal structure, thermostability and magnetic property

“…Rational design and construction of magnetic transition-metal coordination polymers, especially low-dimensional magnetic materials such as single-molecule magnets (SMMs) and singlechain magnets (SCMs), have attracted great attention because of their potential in the fields of high-density storage devices, molecular electronics and so on [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Up to now, remarkable progress has been achieved on this field, serving as the typical example of lots of relevant one-dimensional (1D) transition-metal compounds with fascinating molecular structures and magnetisms [16][17][18][19].…”

“…In particular, the cyano group has been used extensively as a practicable and versatile mediator for magnetic coupling in supramolecular chemistry and crystal engineering [22]. The cyanide-bridged compounds known show a wide range of magnet types, including metamagnets [23,24], room-temperature magnets [25,26], SMMs [27,28], and SCMs [29,10,30]. In light of our continuing interest in this field, we are committed to developing the system to the dicyanamide [N(CN) 2 ] À and paramagnetic [Co(CN) 6 ] 3À building block which can act as important part in uni-, bi-, tridentate manner and both of its homo-and heteroleptic compounds, producing various topologies and intriguing magnetic properties (Scheme 1) [31,32].…”