Wydział Chemii

Jerzy Lisowski

Jarosław Mazurek

2002

Polyhedron

21

811-816

10.1016/S0277-5387(02)00854-9

Naukowa

Angielski

Artykuł

The new enantiopure macrocyclic complexes [LnL]Cl₃·nH₂O or their racemic mixtures [LnracL]Cl₃·nH₂O (Ln=La⁺³, Ce⁺³, Pr⁺³ and Eu⁺³) have been synthesised in a template condensation of trans-1,2-diaminocyclohexane and 2,6-diformylpyridine. The complexes have been studied by ¹H and ¹³C NMR spectroscopy. The signal assignment was based on the COSY, NOESY and HMQC measurements. The X-ray crystal structure of [LaracL]Cl₃ complex has been determined. The lanthanum ion in this complex is coordinated by six nitrogen atoms of the macrocyclic ligand and three chloride anions. The macrocycle exhibits a twist–bent conformation of approximate C₂ symmetry. On the other hand, NMR spectra of the investigated compounds in methanol–chloroform solution indicate effective D₂-symmetry that results from the fast dynamic exchange of chloride anions.New La(III), Ce(III), Pr(III) and Eu(III) macrocyclic complexes were obtained in a template 2+2 condensation of R,R′-1,2-diaminocyclohexane and 2,6-diformylpyridine in the presence of the appropriate lanthanide chloride salts. The ¹H and ¹³C NMR spectra of these paramagnetic complexes were assigned on the basis of COSY, NOESY and HMQC measurements. The analysis of NMR spectra reveals dynamic exchange of the coordinated chloride anions. The single-crystal X-ray structure of the La(III) complex show the twist–bent conformation of the macrocyclic ligand.

https://doi.org/10.1016/S0277-5387(02)00854-9

http://www.elsevier.com