Solvation of the tris(1,10-phenanthroline)iron(II) cation as measured by solubility and nuclear magnetic resonance shifts

Abstract

A model for the solvation of the [Fe(phen)3]2+ cation is proposed based on the geometry of the complex. The solvation energy is considered to be the sum of two parts: that due to the ion-dipole interaction with the solvent and that due to the van der Waals interaction between the solvent and the aromatic ligands. The model was tested, and verified, by measuring the solubilities of Fe(phen)3(C104)2 and naphthalene in ten pure solvents, and in mixtures of water with methanol, acetone, and JV.TV-dimethylformamide. The van der Waals interaction with the ligands was shown to parallel the interaction with naphthalene. The NMR chemical shifts of the 5,6 protons on Fe(phen)32+ were measured in some of the solvent systems.

Solvation of iron(II) complexes of hexadentate tris-diimine Schiff base tripod ligands in alcohol?water and DMSO?water mixtures

“…These comparisons are with the aqua-ion Fe 2þ aq [23], with the hydrophilic nitroprusside anion [Fe(CN) 5 (NO)] 2À [2] and the predominantly hydrophilic complex [Fe(CN) 4 (bipy)] 2À [24], with the marginally lipophilic complex [Fe(hxsb)] 2þ of the hexadentate Schiff base (3) with R = H [25], and with the increasingly lipophilic complexes [Fe(phen) 3 ] 2þ [26] and [Fe(Me 2 bsb) 3 ] 2þ ðMe 2 bsb ¼ ð4ÞÞ [27]. Figure 1 shows that the [Fe(fpyPhg 3 tren)] 2þ cation presents a surface to the surrounding solvent of high lipophilicity, comparable with that of the [Fe(Me 2 bsb) 3 ] 2þ cation, hitherto the most lipophilic of iron(II)-diimine complexes.…”

Solubilities of salts and kinetics of reactions involving inorganic complex ions in aqueous acetone mixtures. Derivation of transfer chemical potentials for ions in these aqueous mixtures at ambient pressure and 298.2 K

“…Interpolated from data in ref. (87). It is perhaps unfortunate that the set of TATB-based transfer chemical potentials does not include data for 2 + and 3 + metal ions.…”

Ruthenium complexes of 3-hydroxy-4-pyranones and of 3-hydroxy-4-pyridinones

“…These relatively small values may be compared with e.g. -11 kJ mol -1 for [Fe(phen) 3 ] 2+ [59], -16 kJ mol -1 for ferrocene [60], and -24 kJ mol -1 for the very hydrophobic/lipophilic complex [Fe(Me 2 bsb) 3 ] 2+ (where Me 2 bsb is the Schiff base from 3,4-dimethylaniline and phenyl 2-pyridyl ketone) [61]. In some of these cases there are doubts as to the precise value of d m l°, but the order of values and their orders of magnitude give a qualitative picture of the relative hydrophobic/lipophilic natures of the complexes and of the degree to which solvation by the methanol component of the binary aqueous solvent media is preferred to hydration.…”