F.J. García-Barros

Coordination chemistry of thiazoline/thiazolidine derivatives. I: Crystal structure of 2-(2-pyridyl)imino-N-(2-thiazolin-2-yl)thiazolidine (PyTT) and study of its interaction with nickel(II)

Abstract The crystal structure of 2-(2-pyridyl)imino-N-(2-thiazolin-2-yl)thiazolidine (PyTT) is reported. The compound diaquabis[2-(2-pyridyl)imino-N-(2-thiazolin-2-yl)thiazolidine]nickel(II) chloride trihydrate has been isolated and characterized by IR, UV–Vis–NIR diffuse reflectance and X-ray diffraction. The complex cation has crystallographic C2 symmetry. The environment around the nickel atom may be described as a distorted octahedral geometry with the metallic atom coordinated to two water molecules [Ni–O(1)=2.114(2) A], two thiazolinic nitrogens [Ni–N(1)=2.061(2) A] and two imino nitrogens [Ni–N(3)=2.086(2) A]. Hydrogen bonding is present in the structure inter-linking PyTT ligands, water molecules and chloride ions.

Studies of the thermal decomposition of (2-thiazolin-2-yl)hydrazine hydrochloride and some metal derivative complexes

Abstract The compound (2-thiazolin-2-yl)hydrazine hydrochloride (TzHyHCl) and the complexes [Ni(TzHy)2(H2O)2]Cl2·2H2O, [ZnCl(TzHy)2]Cl and [Cd(TzHy)(μ-Cl)2]n·nH2O have been studied using spectral (IR and electronic) and thermal (TG and DSC) methods.

The coordination chemistry of thiazoline/thiazolidine derivatives. II: synthesis and characterization of [CoCl2(PyTT)] and [ZnCl2(PyTT)] [PyTT = 2-(2-pyridyl)imino-n-(2-thiazolin-2-yl)thiazolidine]

Abstract The compounds dichloro[2-(2-pyridyl)imino-κ N  N -(2-thiazolin-κ N -2-yl)thiazolidine]cobalt(II) and dichloro[2-(2-pyridyl)imino-κ N  N -(2-thiazolin-κ N -2-yl)thiazolidine]zinc(II) have been isolated and characterized by single crystal X-ray diffraction and IR spectroscopy. Moreover, the cobalt(II) complex has been studied by means of magnetic susceptibility measurements and UV–Vis–NIR diffuse reflectance. Both complexes are isostructural. The environment around the cobalt(II) and zinc(II) atoms may be described as a distorted tetrahedral geometry with the metallic atoms coordinated to two chlorine atoms [CoCl(1)=2.241(1) A; CoCl(2)=2.221(1) A], [ZnCl(1)=2.235(1) A; ZnCl(2)=2.211(1) A], one thiazoline nitrogen [CoN(1)=1.982(2) A], [ZnN(1)=2.021(2) A] and one imino nitrogen [CoN(3)=2.009(1) A], [ZnN(3)=2.056(2) A].

The coordination chemistry of (2-thiazolin-2-yl)hydrazine hydrochloride (TzHyHCl)—II. Study of its interaction with zinc(II) and cadmium(II)

Abstract The complexation equilibria of (2-thiazolin-2-yl)hydrazine hydrochloride (TzHyHCl) with zinc(II) and cadmium(II) have been studied in aqueous solution at 298 K and 0.1 M ionic strength in NaClO 4 . The formation constants were determined and are discussed in terms of the characteristics of the ligand. The compounds [ZnCl(TzHy) 2 ]Cl and [Cd(TzHy)( μ -Cl) 2 ] n · n H 2 O have been isolated and their crystal structures determined. In the Zn II compound, the geometry around the central atom is a distorted trigonal-bipyramid composed of four nitrogen atoms from two TzHy ligands and one chlorine. The Ca II complex is polymeric, with octahedrally coordinated cadmium linked into infinite chains by double (μ-chloro) bridges. The coordination sphere around each cadmium center is completed by two nitrogen atoms from a TzHy ligand. In both cases, the crystal structure is stabilized by an extensive hydrogen-bond network.

Equilibria in aqueous solution between divalent cations and the α-amino acid 2-(benzylamino)-2-deoxy-d-glycero-d-gulo-heptonic acid

Abstract Complex formation in aqueous solution between the amino acid 2-(benzyl-amino)-2-deoxy- d -glycero- d -gulo-heptonic acid and the ions Co 2+ , Ni 2+ , CU 2+ , Zn 2+ , Cd 2+ and Hg 2+ was studied at 298 K and 0.1 M ionic strength in NaClO 4 . The formation constants are discussed in terms of the characteristics of the amino acid.

Complexes of two mannose α-amino acid derivatives with zinc and cadmium

Abstract Complexes of zinc(II) and cadmium(II) with 2-amino-2-deoxy- d -glycero- d -talo heptonic acid (HMa) and 2-(benzylamino)-2-deoxy- d -glycero- d -talo heptonic acid (BnMa) have been obtained. The complexes were characterized by elemental analysis, IR spectroscopy and X-ray powder diffraction. These complexes have a 1:2 metal-to-ligand ratio and an octahedral structure. Coordination occurs through the nitrogen atom of the amino group and oxygen atoms of the bridging carboxylate group. The thermal behaviour of the complexes has also been studied.

A thermal and IR study of metal complexes of 2-amino-2-deoxy-d-glycero-l-gluco heptonic acid

Abstract Complexes of 2-amino-2-deoxy- d- glycero- l -gluco heptonic acid (GH) and Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) have been synthesised and characterised by elemental analysis and IR spectroscopy. The complexes have a general formula: [M(G) 2 (H 2 O) 2 ] with variable water of hydration, except for the Cu(II) compound which is anhydrous [Cu(G) 2 ]. The thermal behaviour of these complexes has been studied by TG and DSC techniques. The thermal data indicate that for the Co(II), Ni(II), and Cu(II) complexes, the ligand is chelated via the carboxylate − and amino functional groups, whereas for the Mn(II) and Fe(II) complexes, the amino group remains protonated and does not bond to the metal.

The coordination chemistry of (2-thiazolin-2-yl)hydrazine hydrochloride (TzHyHCl)—III. Study of its interaction with cobalt and crystal structure of [Co(TzHy)3]Cl3·2H2O

Abstract The complexation equilibria of (2-thiazolin-2-yl)hydrazine hydrochloride (TzHyHCl) with cobalt(II) have been studied in aqueous solution at 298 K and 0.1 M ionic strength in NaClO4. The formation constants were determined and discussed in terms of the characteristics of the ligand. The compound [Co(TzHy)3] Cl3·2H2O has been isolated and characterized by IR, UV-vis-NIR diffuse reflectance and thermal measurements, and its crystal and molecular structure determined by X-ray analysis. In this compound the complex cation shows a distorted octahedral geometry with the cobalt atom coordinated to three terminal hydrazine nitrogen atoms [ average CoN = 1.973 A ] and three thiazoline nitrogen atoms [ average CoN = 1.900 A ] . Angles NCoN for adjacent nitrogen donors are comprised between 94.9 and 82.8°. According to the position of the ligands, the complex can be described as a facial isomer. A hydrogen bond scheme is present in the structure interlinking TzHy ligands, water molecules and chloride ions.

Spectroscopic characterization and thermal behavior of two sugar α-amino acids

Abstract The carbohydrate α-amino acids, 2-amino-2-deoxy- d -glycero- d -talo-heptonic acid and 2-amino-2-deoxy- d -glycero- l -gluco-heptonic acid, have been characterized by means of both spectral (IR) and thermal (TG and DSC) methods. The acid—base characteristics of the amino acids have been studied at 298 K and ionic strength I = 0.1 M in aqueous solution.

Thermal and spectroscopic study of some metal complexes of 6-chloropurine

Abstract Solid complexes of 6-chloropurine (6-C1PH) with the cations Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) have been obtained and characterised on the basis of elemental analysis and IR spectroscopy. Except for the Hg(II) compound, Hg(6-ClP)Cl, the remaining complexes have the general formula M(6-ClP) 2 with a variable amount of water. The thermal behaviour of these complexes has been studied by TG and DSC techniques. The IR spectra of the compounds are also discussed.