Untitled

Solvatochromism and solvation of transition metal complexes in ternary aqueous solvent media

“…This situation closely parallels that of Fe(etmalt) 3 , where etmalt = ethylmaltolate (2-ethyl-3-hydroxy-4-pyranonate), in water-1-octanol and in water-1-hexanol mixtures, where strong preferential solvation by water leads to much increased solubility on adding small amounts of water to the respective alcohol [46]. The connection between indications of preferential solvation from solvatochromism and from transfer chemical potentials has been discussed elsewhere [49]. Marked preferential solvation by water has also been deduced from the solvatochromic behaviour of Fe(CN) 2 (acpyox) 2 , where acpyox = 2-acetylpyridineketoximate (C 5 H 4 NÁC(Me)=NO -), in the water-t-BuOH-PEG system [47].…”

Effective Repression of the Fragmentation of a Hexadentate Ligand Bearing an Auto‐Immolable Pendant Arm by Iron Coordination

“…Also, the issue of substitution kinetics [31] of the coordinating imine moiety (pyridyl or other) by water needs to be addressed. [32,33] To this end, studies of remote derivatives of 1 are currently in progress.…”

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

“…The high stability and substitution-inertness [9,13], the intense colour of these complexes and the low watersolubility of their perchlorate salts makes them excellent candidates for the determination of transfer chemical potentials from solubility measurements. The crystal structures of the perchlorate and tetrafluoroborate [16] salts exhibit identical (within experimental uncertainties) bond distances and angles in the respective [Fe(fpyHg 3 tren)] 2þ cations.…”

“…For these complexes water molecules are sufficiently small to penetrate between the ligand planes to hydrate the central Fe 2þ -as demonstrated in, The use of the transfer chemical potentials for these three tripodal complexes for initial state-transition state analysis of solvent effects on reactivity trends for base hydrolysis is rather limited. Kinetic data are available for [Fe(fpyHg 3 tren)] 2þ only in water, 40% methanol [9], and 60% DMSO [13], while rate constants for base hydrolysis of [Fe(fpyMeg 3 tren)] 2þ and [Fe(fpyPhg 3 tren)] 2þ are only available in 60% DMSO [13] as reaction in water is extremely slow. Furthermore the rate laws for these latter complexes are not simple, there being terms in [OH À ], [OH À ] 2 , and [OH À ] 3 .…”

“…Such inertness to substitution makes this type of complex extremely useful for kinetic studies, especially of oxidation by such slow oxidants as peroxodisulphate [10] or thallium(III) [11], where often rate-limiting dissociation, with subsequent oxidation of iron(II) intermediates, occurs in parallel with, or faster than, direct oxidation [12], thus making kinetic studies difficult or impossible. We have reported earlier on solvation and the reactivity of cage and linear complexes, and on the intermediate reactivity [9,13] of semi-encapsulated complexes of tripodal ligands (3) [14][15][16]. These ligands are derived from tris(2-aminoethyl)amine and pyridine 2-carboxaldehyde, 2-acetylpyridine, or 2-benzoylpyridine; (3) with R = H, Me, or Ph, respectively.…”