Iron complexes magnetic properties

Iron, tris(hexafluoroacetylacetone)-structure, 65 Iron, tris(oxalato)-chemical actinometer, 409 Iron, tris(l,10-phenanthroline)-absorptiometry, 549 racemization, 466 solid state, 467 structure, 64 Iron(O) complexes magnetic properties, 274 Iron(II) complexes magnetic behavior, 273 spectra, 253 Iron(III) complexes equilibrium constant solvent effect, 516 liquid-liquid extraction, 539 magnetic behavior, 272 spectra, 253 Iron(IV) complexes magnetic behavior, 272 Isocyanates metal complexes hydrolysis, 429 Isokinetic effect ligand exchange solid state, 469 Isomerism, 179-208 configurational, 180, 188 constitutional, 180,182 coordination, 183 detection, 180 history, 24... 

Several interesting features of the magnetic properties of [Fe(HB(pz)3)2] are revealed in Fig. 1. First, between 78 and ca. 295 K the magnetic moment is not zero, as might be expected for a diamagnetic compound, but rather increases slightly from a moment of ca. 0.6 jUb at 78 K. This non-zero moment is typical of low-spin iron(II) complexes, and is a consequence of sec-... 

The inverse magnetic susceptibility and the effective magnetic moment, jueff, of [Fe(HC(3,5-(CH3)2pz)3)2](BF4)2 are shown in Fig. 16 where it is immediately obvious that the magnetic properties of this complex are quite unusual [46]. Above ca. 210 K the eff of ca. 5.0 is clearly that expected of a high-spin iron(II) complex. But below ca. 190 K the moment decreases to a substantially lower value of ca. 3.7 /uB. Further, at ca. 90 K there is a small irreversible change in susceptibility and moment, a change that is associated with crystal reorientation in the applied field. The reason for the abrupt decrease in the moment at ca. 200 K to ca. 3.7 becomes apparent from a study of the Mossbauer spectra of [Fe(HC(3,5-(CH3)2pz)3)2](BF4)2. 

Keywords Iron(II) spin crossover complexes Multidentate ligands Ligand design Synthesis Magnetic properties... 

Earlier Nelson prepared a few pentadentate macrocydic ligands which form iron(II) complexes with unusual magnetic properties. With the N3S2 ligand (15) he obtained a series of hexacoordinated iron(II) complexes of the type [Fe 15X]+. 

The binuclear iron unit consisting of a (p,-oxo(or hydroxo))bis(p.-carboxylato)diiron core is a potential common structural feature of the active sites of hemerythrin, ribonucleotide reductase, and the purple acid phosphatases. Synthetic complexes having such a binuclear core have recently been prepared their characterization has greatly facilitated the comparison of the active sites of the various proteins. The extent of structural analogy among the different forms of the proteins is discussed in light of their spectroscopic and magnetic properties. It is clear that this binuclear core represents yet another stractural motif with the versatility to participate in different protein functions. 

The tetranuclear complex [Fe20(O2CCH3)2 (tpbn)2 ] 2 recently reported(14) is not an 0x0-iron aggregate according to our definition but comprises two quasi-independent dinuclear p-oxo diiron units. Its spectroscopic and magnetic properties are consistent with this view. 

Bithiazole, 4,4 -btz = (97), is not a diimine its iron(II) complex [Fe(4,4 -btz)3] is only weakly colored but its magnetic properties and Fe—N bond distances 1.970-1.973A suggest that the ligand field effect of 4,4 -btz is not enormously less than that of bipy. ... 

There is a number of synthetic substitutes for natural ferritin and the properties of these have been compared with those of ferritin. The synthetic polysaccharide iron complex (PIC), has a magnetic blocking temperature of 48K (Mohie-Eldin et al. 1994). Iron-dextran complexes are used as a substitute for ferritin in the treatment of anaemia. The iron cores of these complexes consist not of ferrihydrite, but of very poorly crystalline akaganeite with magnetic blocking temperatures of between 150 and 290 K (Muller, 1967 Knight et al. 1999) which were lowered from 55K to 35 and 25K, if prepared in the presence of 0.250 and 0.284 Al/(A1 -i- Fe), respectively (Cheng et al.2001). 

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