Sinteza i karakterizacija nekih metal(II) i metal(III) kompleksa sa diaminopolikarboksilatnim ligandima

Abstract

U prvom delu ove doktorske disertacije, na osnovu rezultata rendgenske strukturne analize, opisana je kristalna struktura {[Sr2(1,3-pdta)(H2O)6].H2O}n kompleksa. Nađeno je da se u koordinacionoj sferi svakog Sr(II) jona, pored četiri molekula vode, nalaze jedan atom azota i četiri atoma kiseonika karboksilnih grupa koje potiču iz 1,3-propandiamin-N,N,N’,N’-tetraacetato liganda (1,3-pdta). Dva Sr(II) jona u {[Sr2(1,3-pdta)(H2O)6].H2O}n kompleksu su međusobno povezani preko diaminskog lanca 1,3-pdta liganda. Pored toga, svaki Sr(II) jon je mostno povezan preko dva karboksilna kiseonikova atoma i molekula vode sa dva susedna Sr(II) jona. Na bazi rezultata difrakcije rendgenskih zraka sa prahova i rezultata IR spektroskopije za različite M(II)-1,3-pdta komplekse, ispitivan je način koordinacije 1,3-pdta liganda u zavisnosti od veličine centralnih jona metala, kao i tip kompleksa koji pri tome nastaje. Rezultati ovih ispitivanja su objavljeni u radu: U. Rychlewska, B. Warżajtis, D. D. Radanović, N. S. Drašković, I. M. Stanojević and M. I. Djuran, Polyhedron, 30 (2011) 983-989. U drugom delu disertacije opisana je sinteza i spektroskopska (UV-Vis i IR spektri) karakterizacija kompleksa nikla(II) i bakra(II) sa novim heksadentatnim (±)-1,3-pentandiamin-N,N,N’,N’-tetraacetato (1,3-pndta) i pentadentatnim (±)-1,3-pentandiamin-N,N,N’-triacetato (1,3-pnd3a) ligandima. Ovi ligandi su strukturno slični sa ranije opisanim heksadentatnim 1,3-propandiamin-N,N,N’,N’- tetraacetato (1,3-pdta) i pentadentatnim 1,3-propandiamin-N,N,N’-triacetato (1,3-pd3a) ligandima. Rezultati rendgenske strukturne analize dobijeni za oktaedarski Mg[Ni(1,3-pndta)]10H2O kompleks ukazuju da prisustvo etil- supstituenta na α-ugljenikovom atomu doprinosi stvaranju novog hiralnog centra, što ima za posledicu građenje izomera (ΔΛΔ (R) i ΛΔΛ (S)) koji se razlikuju u konfiguraciji ovog centra (R ili S). Nađeno je da δ uvijena forma leđnog diaminskog prstena uslovljava Λ konfiguraciju, dok je u slučaju λ uvijene forme ovog prstena potvrđena Δ konfiguracija [Ni(1,3-pndta)]2- kompleksa. U slučaju stereoizomera ΔΛΔ (R) i ΛΔΛ (S) nađeno je da etil grupa zauzima ekvatorijalni položaj na centralnom šestočlanom diaminskom prstenu. Elektronski apsorpcioni i infra-crveni spektri Ni(II) i Cu(II) kompleksa sa heksadentatno koordinovanim 1,3-pndta ligandom (Mg[Ni(1,3-pndta)]10H2O i Mg[Cu(1,3- pndta)].7H2O) i pentadentatno koordinovanim 1,3-pnd3a ligandom (Mg[Ni2(1,3- pnd3a)2]8H2O i Mg[Cu2(1,3-pnd3a)2].7H2O) su poređeni sa odgovarajućim spektrima analognih Mg[Ni(1,3-pdta)].8H2O i Mg[Cu(1,3-pdta)].8H2O i Mg[Cu2(1,3-pd3a)2].7H2O kompleksa poznatih kristalnih struktura. Rezultati ovih ispitivanja su objavljeni u radu: N. S. Drašković, D. D. Radanović, U. Rychlewska, B. Warżajtis, I. M. Stanojević and M. I. Djuran, Polyhedron, 43 (2012) 185-193. U trećem delu disertacije opisana je sinteza i karakterizacija serije hrom(III) kompleksa sa heksadentatno koordinovanim ()-1,3-pentandiamin- N,N,N,N-tetraacetato (1,3-pndta) ligandom i Na+, K+ i Ca2+ jonima kao kontra- katjonima. Struktura ovih kompleksa je potvrđena na osnovu rendgenske strukturne analize. Ispitivan je uticaj kontra-katjona i supstituisanog diaminskog prstena na samoorganizaciju molekula i stepen hidratacije molekula u kristalima. Različiti načini vezivanja karboksilnih grupa za jone metala uslovljavaju formiranje 3D, 2D i 1D polimernih struktura. Elektronski apsorpcioni i 1H NMR spektri [Cr(1,3-pndta)]- kompleksa su diskutovani u odnosu na [Cr(1,3-pdta)]- komplekse poznatih kristalnih struktura. Rezultati ovih ispitivanja su objavljeni u radu: B. Warżajtis, U. Rychlewska, D. D. Radanović, I. M. Stanojević, N. S. Drašković, N. S. Radulović and M. I. Djuran, Polyhedron, 67 (2014) 270-278.

The first part of this thesis deals with synthesis and the X-ray characterization of the missing homonuclear s-block metal complex {[Sr2(1,3-pdta)(H2O)6].H2O}n. In the title compound, the hexadentate 1,3-propanediaminetetraacetate (1,3-pdta) ligand joins to two Sr(II) centers via the diamine chain. Moreover, each Sr(II) is bridged through two carboxylate O atoms and a water molecule to two neighboring Sr(II) ions. The coordination sphere around each Sr(II) ion consists of one diamine nitrogen, four carboxylate oxygens and four water molecules. Comparison with the previously reported M(II)-1,3-pdta complexes reveals that increasing of the ion size results in incorporation of water molecules into its first coordination sphere and consequent increase of the C.N. from six to seven or eight while keeping the hexadentate coordination mode of the ligand. Further increase of the metal ion size leads to the loss of the chelating properties of the diamine and formation of bis-tridentate complex. Associated with it is the change in the binding mode of the carboxylate groups. This forms the basis for classification of the divalent metal 1,3-pdta complexes into five distinct structural classes. Additionally, in the present study the X-ray powder diffraction and IR spectroscopy were used for distinguishing different structural types of M(II)-1,3-pdta complexes including Ba[Ba(1,3- pdta)]·2H2O which has been used for their preparation. The above mentioned results have been published in the paper: U. Rychlewska, B. Warżajtis, D. D. Radanović, N. S. Drašković, I. M. Stanojević and M. I. Djuran, Polyhedron, 30 (2011) 983-989. In the second part of this thesis, structural variations modulated by ethyl side group have been analyzed for nickel(II) and copper(II) complexes with (±)-1,3- Summary IV pentanediamine-N,N,N’,N’-tetraacetate ligand (1,3-pndta) and its pentadentate derivative (±)-1,3-pentanediamine-N,N,N’-triaacetate (1,3-pnd3a). X-ray results obtained for the octahedral 1,3-pndta-Ni(II) complex indicate the distinct correlation of the central chirality of the metal with the chirality at the diamine α-carbon, which leads to the formation of a racemic mixture of ΔΛΔ(R) and ΛΔΛ(S) enantiomeric anionic complexes, where the R and S labels designate the absolute configuration at the ligand (ethyl-substituted) stereogenic center. These stereoisomers are those required to maintain an equatorial ethyl group on the central six-membered chelate ring, whose conformation is λ twist-boat for the ΔΛΔ isomer and δ twist-boat for the ΛΔΛ isomer. Ethyl group discernibly affects the variation of the Ni–N and Ni–O bond lengths compared to the analogous complex lacking the substitution of one of the diastereotopic diamine CH2 hydrogens and functions as steric bulkiness which hampers an efficient and of high symmetry packing, observed in the crystals of the parent complex. The infrared and electronic absorption spectra of hexadentate Mg[Ni(1,3- pndta)]10H2O and Mg[Cu(1,3-pndta)].7H2O, and pentadentate Mg[Ni2(1,3- pnd3a)2].8H2O and Mg[Cu2(1,3-pnd3a)2].7H2O complexes are presented and discussed in comparison with those of the analogous Mg[Ni(1,3-pdta)].8H2O, Mg[Cu(1,3-pdta)].8H2O and Mg[Cu2(1,3-pd3a)2].7H2O complexes of known crystal structures. The obtained results from this investigation has been published in: N. S. Drašković, D. D. Radanović, U. Rychlewska, B. Warżajtis, I. M. Stanojević and M. I. Djuran, Polyhedron, 43 (2012) 185-193. Finally in this thesis, series of Na+, K+ and Ca2+ salts of chromium(III) complexes with the hexadentate ()-1,3-pentanediamine-N,N,N,N-tetraacetate (1,3-pndta) ligand was evaluated. The extent of distortion exhibited in the geometry of these octahedral complexes was computed and related to the configuration at the metal center and the ligand stereogenic center. The materials have been used to investigate the effect of the counter ion and the diamine ring substitution on the self organization and degree of hydration of these molecules in crystals. Various modes of carboxylate binding to metal atoms have been related to the formation of 3D, 2D and 1D polymeric structures. The electronic absorption and 1H NMR spectra of 1,3-pndta-Cr(III) complexes are discussed in relation to those of 1,3-pdta-Cr(III) complex (1,3-propanediamine-N,N,N,N-tetraacetate ion) of known structure. The results of this investigation has been published in: B. Warżajtis, U. Rychlewska, D. D. Radanović, I. M. Stanojević, N. S. Drašković, N. S. Radulović and M. I. Djuran, Polyhedron, 67 (2014) 270-278.