Co-ordination complexes as organic–inorganic layer magnets

Abstract

Examples are given of transition-metal co-ordination complexes that give rise to alternating layers of organic and inorganic moieties in the solid state exhibiting finite zero-field magnetisation at low temperature. The mechanisms of magnetic exchange included are ferromagnetism, ferrimagnetism and canted antiferromagnetism.

Assembling Magnetic Nanowires into Networks: A Layered CoIICarboxylate Coordination Polymer Exhibiting Single‐Chain‐Magnet Behavior

“…As σ‐bonding linkers are significantly weaker mediators of the spin carriers,8 crystal engineering with a judicious choice of σ‐bonding ditopic linkers may allow us to covalently link 1D Ising ferro‐ or ferrimagnetic chains into 2D or 3D networks without significant deterioration of the one‐dimensional magnetism of the SCMs in the 2D or 3D structures, although no genuine example has been reported so far. In this regard, trans ‐1,2‐cyclohexanedicarboxylate ( trans ‐1,2‐chdc) is a good candidate, since it was demonstrated to be a very weak magnetic mediator9 due to alternation effects 8…”

Solvothermal Synthesis of the Canted Antiferromagnet {K2[CoO3PCH2N(CH2CO2)2]}6⋅x H2O

“…This is equivalent to 0.7 % of that expected for ferromagnetic ordering. This behavior is characteristic of canted antiferromagnetism [7,8] in which a predominantly antiferromagnetic phase possesses a small spontaneous magnetization due to a small deviation from a strictly antiparallel arrangement. A series of temperature scans in various fields (Figure 3) shows a pronounced field dependence of the low-temperature phase confirming our assignment.…”

“…That a phase change from paramagnet to canted antiferromagnet occurs without an intermediate antiferromagnetic phase is indicative of the predominant influence of D, the single ion anisotropy over J, the exchange coupling which would have been expected from structural considerations. It is becoming evident that canted antiferromagnetism is surprisingly common in materials with extended structures [8] but there are few examples of this behavior for molecular materials with the exception of some purely organic radicals. [9] Hence we believe this to be the first observation of canting for an inorganic molecular compound.…”

“…Unlabled shaded spheres in the center of the ring represent the positions of the disordered lattice water molecules. Selected bond lengths [] and angles[8]: Co ± O1 2.027…”

Synthesis, structure and magnetic behavior of new 1D metal–organic coordination polymer with Fe3O core

“…In particular, new mixed valence iron(II) formate, (Me 2 NH 2 )[Fe 2 (HCOO) 6 ], was recently described [8]. This compound has 3D polymeric framework and demonstrates spontaneous magnetization at low temperatures followed by negative magnetization, a very rarely observed phenomenon [9][10][11][12][13]. Well-known iron carboxylates with Fe 3 O core are another example where interesting magnetic properties may render through interactions over short formate bridging ligands [14][15][16].…”