Iron solvates

Evidence for the solvated electron e (aq) can be obtained reaction of sodium vapour with ice in the complete absence of air at 273 K gives a blue colour (cf. the reaction of sodium with liquid ammonia, p. 126). Magnesium, zinc and iron react with steam at elevated temperatures to yield hydrogen, and a few metals, in the presence of air, form a surface layer of oxide or hydroxide, for example iron, lead and aluminium. These reactions are more fully considered under the respective metals. Water is not easily oxidised but fluorine and chlorine are both capable of liberating oxygen ... 

The mode of extraction in these oxonium systems may be illustrated by considering the ether extraction of iron(III) from strong hydrochloric acid solution. In the aqueous phase chloride ions replace the water molecules coordinated to the Fe3+ ion, yielding the tetrahedral FeCl ion. It is recognised that the hydrated hydronium ion, H30 + (H20)3 or HgO,, normally pairs with the complex halo-anions, but in the presence of the organic solvent, solvent molecules enter the aqueous phase and compete with water for positions in the solvation shell of the proton. On this basis the primary species extracted into the ether (R20) phase is considered to be [H30(R20)3, FeCl ] although aggregation of this species may occur in solvents of low dielectric constant. 

The solvation property of the cations of this very polar aprotic solvent can make some salts more stable. Therefore, aluminium, sodium, mercury or silver perchlorate solutions are explosive. The same goes for iron (III) nitrate solutions. 

Two dendrimers based on Fe-porphyrin core carrying peptide-like branches of different sizes have been synthesized in order to have more open and a more densely packed (23) structures [43]. The electrochemical behavior has been examined in CH2C12 and in aqueous solution. In the less polar solvent, the two dendrimers show similar potentials for the Fem/Fen couple, suggesting that the iron porphyrins in both the more open and the more densely packed dendrimers experience similar microenvironments. On the contrary, in water the behavior of the two dendrimers is very different since the reduction from Fem to Fe11 is much easier for the densely packed dendrimer. This result can be explained considering that in the dendrimer with the relatively open structure the aqueous solvation of the iron porphyrin is still possible, whereas in the densely packed one the contact between the heme and the external solvent is signifi-... 

Mixtures of the sulfoxide with metal salts of oxoacids are powerful explosives. Examples are aluminium perchlorate, sodium perchlorate and iron(III) nitrate [1], The water in hydrated oxosalts (aluminium perchlorate, iron(III) perchlorate, iron(III) nitrate) may be partially or totally replaced by dimethyl (or other) sulfoxide to give solvated salts useful as explosives [2], Metal nitrates and perchlorates solvated with DMSO are generally powerfully explosive, and under certain conditions a violent reaction is easily triggered [3], Several other explosions involving perchlorates and the sulfoxide have been reported. 

Thermochemistry. Chen et al.168 combined the Kohn-Sham formalism with finite difference calculations of the reaction field potential. The effect of mobile ions into on the reaction field potential Poisson-Boltzman equation. The authors used the DFT(B88/P86)/SCRF method to study solvation energies, dipole moments of solvated molecules, and absolute pKa values for a variety of small organic molecules. The list of molecules studied with this approach was subsequently extended182. A simplified version, where the reaction field was calculated only at the end of the SCF cycle, was applied to study redox potentials of several iron-sulphur clusters181. 

The iron slurries show exceptional reactivity toward oxidative addition reactions with carbon halogen bonds. In fact, the reaction with C.FcI is so exothermic that the slurry has to be cooled to 0 °C before the addition of C F L The reaction of iron with C F Br is also quite exothermic, hence, even for this addition, the iron slurry is cooled to about 0 ° C. The organoiron compound formed in the above reactions, solvated Fe(C.F )2, reacts with CO at room temperature and ambient pressure to yiela Fe(C,F3)2(CO)2(DMEL. 

A more subtle chemical influence is the variation of the anion associated with a cationic spin crossover system, or of the nature and degree of solvation of salts or neutral species. These variations can result in the displacement of the transition temperature, even to the extent that SCO is no longer observed, or may also cause a fundamental change in the nature of the transition, for example from abrupt to gradual. The influence of the anion was first noted for salts of [Co(trpy)2]2+ [142] and later for iron(II) in salts of [Fe(paptH)2]2+ [143] and of [Fe(pic)3]2+ [127]. For the [Fe(pic)3]2+ salts the degree of completion and steepness of the ST curve increases in the order io-dide[Pg.41]

About twenty years ago we reported on the di-isothiocyanato iron(II) complex of the tetradentate ligand tpa (tris(2-pyridylmethyl)amine) [7] (6). It was shown that this complex exhibits the spin crossover phenomenon with a critical temperature Tm of about 170 K. Several different solvated phases of the same system have since been characterized by Chansou et al. [8]. The unsolvated phase which can be isolated from an aqueous solution has been investigated by nuclear forward scattering (NFS), nuclear inelastic scattering (NIS) [9], extended x-ray absorption fine structure (EXAFS) spectroscopy, conventional Mossbauer spectroscopy, and by measurements of the magnetic susceptibility (SQUID) [10-13]. The various measurements consistently show that the transition is complete and abrupt and it exhibits a hysteresis loop between 102 and 110 K. 

Iron(III) compounds of 3-OEt-salAPA have been widely studied [127, 128, 139-145]. Both the anion and the incorporated solvent molecule influence the spin crossover behaviour of the complex salts. Thus T1/2 for [Fe(3-OEt-salAPA)2]ClC>4 is 295 K, whereas that for the dichloromethane solvate is 152 K [140]. The transition in [Fe(3-0Et-salAPA)2]C104 and [Fe(3-OEt-salA-PA)2]BPh4 is more gradual and occurs at a somewhat higher temperature than that for the benzene solvate [Fe(3-0Et-salAPA)2]C104-C6H6 [141]. 

Iron tartaric acid -sodium complex solution KC4H306)3Fe]Na6 EWNN Good solvating properties, extremely high salt concentration, slight oxidative degradation, coloured (green)... 

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