Naslov
Different coordination environments of iron(III) and pseudopolymorphism in complexes with dipicolinic acid and 2-amino-6-picoline. The influence of molar ratio and solvent type

Autori
Tabatabaee, Masoumeh ; Dadkhodaee, Maryam ; Kukovec, Boris-Marko

Izvornik
Polyhedron (0277-5387) 51 (2013); 316-322

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
pseudopolymorphism; cocrystal; dipicolinic acid; seven-coordinated iron(III); 2-amino-6-picoline

Sažetak
Three iron(III) compounds of dipicolinic acid (dipicH2) and 2-amino-6-picoline (Hamp-6-pic), formulated as (Hamp-6-pic)[Fe(dipic)2][Fe(dipic) (NO3)(H2O)2]•2H2O (1), (Hamp-6-pic)[Fe(dipic)2]• H2O (2) and {; ; (Hamp-6-pic)[Fe(dipic)2]}; ; 2•H2O (3) (Hamp-6-pic+ = 2-amino-6-picolinium) were prepared and characterized by spectroscopic methods (IR and UV-Vis) and their molecular and crystal structures were determined by X-ray crystal structure analysis. Compound 1 was prepared by the reaction of Fe(NO3)3 • 6H2O with dipicolinic acid and 2- amino-6-picoline in aqueous solution in the molar ratio of 1:1:1, while 2 was obtained by the same reaction but in the molar ratio of 2:2:1. A recrystallization of 2 in the mixture of methanol and ethanol led to the formation of 3. The neutral complex [Fe(dipic)(NO3)(H2O)2] is co-crystallized with (Hamp-6-pic)[Fe(dipic)2] in 1. Fe(III) ion is seven-coordinated (in a distorted pentagonal-bipyramidal geometry) by a tridentate dipicolinate and a bidentate nitrate ion and the coordination is completed by two water molecules in the axial positions. Complexes 2 and 3 are examples of pseudopolymorphs which differ in the number of co-crystallized water molecules and in the crystal system (monoclinic (2) or triclinic (3)).

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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