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Synthesis and study of homo- and heteronuclear iron clusters with di- and tricloroacetic acids


Author: Denis Prodius
Degree:doctor of chemistry
Speciality: 02.00.01 - Inorganic chemistry
Year:2007
Scientific adviser: Constantin Turtă
doctor habilitat, professor, Institute of Chemistry, Academy of Sciences of Moldova
Institution:
Scientific council:

Status

The thesis was presented on the 30 April, 2007
Approved by NCAA on the 14 June, 2007

Abstract

Adobe PDF document0.79 Mb / in romanian

Thesis

CZU 541.49+546.723’40’650+ +537.621+543.429.3+543.442.3

Adobe PDF document 5.15 Mb / in romanian
125 pages

Keywords

oxo-carboxylates of iron (III), heteropolynuclear clusters, x-ray study, magnetic exchange interactions, Mossbauer spectroscopy, stimulators of biosynthesis

Summary

The work is devoted to the synthesis and research to process of formation of the homo- and heteropolynuclear oxo-carboxylate clusters of iron(III) with halogenocarboxylic acids (dicloroacetic, tricloroacetic) and different solvents. About 26 complexes were synthesised for the first time, which structure was revealed by the following physical methods: IR and thermogravimetry, magnetochemistry, electron paramagnetic resonance, Mössbauer spectroscopy and x-ray structural analysis investigations are described in the work.

The methods of synthesis of three-nuclear heterometallic carboxylates with common formula [Fe2MllO(CCl3COO)6(THF)n] (Mll = Mg; Ca, Sr, Ba) are described for the first time, which have been prepared by means of interaction of iron(III) nitrate with tricloroacetates of bivalent metal. As result of interaction between lanthanide(III) nitrate and heteronuclear iron tricloroacetate [Fe2BaO(CCl3COO)6(THF)6] the new row of heterometallic tetranuclear carboxylates [Fe3LnO2(CCl3COO)8(H2О)(THF)3] are obtained.

It was demonstrated that problem of metal position’s localization in {Fe2MO} fragment can be successfully solved via inclusion of monodenthate ligands with different affinity to iron and metal into cluster’s inner sphere.

In the wide range of temperature the magnetic susceptibilities of representatives of the homo- and heteronuclear iron carboxylates have been studied. It was shown that the anomaly magnetic properties are based on antiferromagnetic interaction between three paramagnetic metal ions. On the example of heterotetranuclear complexe [Fe3EuO2(CCl3COO)8(H2О)(THF)3] for the first time was demonstrated possibility of intramolecular ferromagnetic interaction in such type of carboxylates containing iron.

It was shown, that the property of a single molecular magnet (SMM) of dodecanuclear oxocarboxylate cluster with {Mn12O12} fragment can be maintained even at change of number of electrons in system, which takes place with replacement of ions Mn (III) on Fe (III).

Was revealed that [Fe2M(Mn,Ni)O(CCl3COO)6(CH3OH)3] complexes posses properties as biostimulators of carothenoid biosynthesis and biomass quantity increasing of Rhodotorula gracilis yeast’s cultivation.