E. Colacio-Rodriguez

Platinum and palladium complexes of 3-methyl orotic acid: a route toward palladium complexes with good antitumor activity.

In order to design and develop potential anticancer drugs involving the same structural pattern as platinum(II) antitumor complexes, complexes of palladium and platinum with 3-methyl-orotic acid as the leaving ligand have been synthesized. The study of the anticancer activity of these compounds toward L1210 leukemia and sarcoma 180 in mice is presented and discussed in terms of the nature of the ligand and the metal involved. The (3-methylorotato)(1,2-diamino-cyclohexane) palladium(II) has an activity (sarcoma 180) similar to that for cis-DDP itself. The crystal structure of (3-methylorotato)(dl-trans-1,2-diaminocyclohexane) platinum(II) is described.

Thermal studies on purine complexes. III. Palladium complexes of xanthine and some xanthine derivatives

Abstract Some complexes |PdL 2 Cl 2 | (where L = xanthine, theophylline, theobromine, 3,8-dimethylxanthine, caffeine and 1,3,8-trimethylxanthine) have been prepared in acid medium. Their structure has been established from IR and 1 H-NMR data. The thermal behaviour of these complexes has been studied by TG, DTG and DSC techniques. Heats of dehalogenation have been calculated from the DSC curves.

Thermal studies on purine complexes. IV. Thermal behaviour of some tetrachloroaurates of xanthine derivatives

Abstract Gold compounds [LH + 2 ][AuCl 4 ] (where LH = theophylline, theobromine, 3,8-dimethylxanthine, caffeine and 1,3,8-trimethylxanthine) were prepared in acid medium, and characterized on the basis of IR, 1 H-NMR and magnetic studies. The thermal behaviour of these salts was studied using TG, DTG and DSC techniques. Heats of dehalogenation were calculated from DSC curves. These heats fluctuate between 81.8 and 184.3 kJ mole −1 .

Thermal studies on purine complexes. I. Thermal behaviour of some xanthine complexes of cobalt(II), copper(II) and cadmium(II)

Abstract Cobalt, copper and cadmium xanthinate tetrahydrates have been prepared in aqueous medium, and characterized on the basis of elemental analysis, IR and 1 HNMR studies. The thermal behaviour of these compounds has been studied using TG, DTG and DSC techniques. Heats of dehydration have been calculated from DSC curves.

The crystal structure and electronic properties of the Bis(1,3-dimethyl-5-diazophenyl-6-amino uracilato) copper(II) complex, dimethyl sulfoxide solvate - a new pseudotetrahedral CuN4 complex

Abstract The crystal structure of the title complex has been determined by X-ray diffraction technique. The crystals are monoclinic, space group P 2 1 / n , with a = 12.878(2), b = 14.791(1), c = 17.268(2) A, β = 109.79(1)°, Z = 4, R = 0.057 for 2514 reflections. There are two ligands of 1,3-dimethyl-5-diazophenyl- 6-amino uracilato anions in bidentate coordination to a copper(II) ion per asymmetric unit. The ligands are in cis -arrangement to each other. The copper environment is pseudotetrahedral, with a dihedral angle φ of 39.7° between the two CuN 4 ligand planes. This geometry seems to result from steric interaction between the ligands. The coordination of each molecule of the ligand takes place through the nitrogen atom of the deprotonated 6-amino group and a nitrogen of the azo group. The structure is stabilised by extensive stacking interactions between the phenyl rings as well as the pyrimidine rings. A pair of hydrogen-bonded interactions between the solvent molecule and the two ligands further stabilise the structure. The magnetic moment, ESR and electronic reflectance spectrum are in accordance with the observed molecular structure. A linear correlation between the highest energy d—d transition and the dihedral angle for several pseudotetrahedral N 4 complexes has been proposed.

Thermal studies on purine complexes. V. Thermal behaviour of tetrachloropalladates of theophylline and theobromine and theophylline complexes of Cd(II) and Hg(II)

Abstract Palladium compounds |LH + 2 | 2 |PdCl 4 | (where LH= theophylline or theobromine) and theophylline complexes CdT 2 (OH 2 ) 4 , HgTCl·H 2 O and Hg(TH)Cl 2 , have been prepared in acid and hydroethanolic medium, respectively, and studied by IR and 1 H-NMR spectroscopy. The thermal behaviour of these compounds has been studied using TG, DTG and DSC techniques. Dehydration and dehalogenation enthalpies have been calculated.

Thermal behaviour of xanthinium salts of Zn(II), Cd(II) and Hg(II)

Salts [XanH+]2[MCl42-] (where XanH+=protonated form of xanthine and M=Zn(II), Cd(II) and Hg(II) have been synthesized and studied by IR,1H-NMR, TG and DSC. The metal is not coordinated to the ligand and forms a salt-like structure. The cationic proton is on N(7). Thermal decomposition of these salts occurs in two steps: (i) dehalogenation and (ii) decomposition. Dehalogenation enthalpies have been calculated from DSC curves.Zusammenfassung(XanH+)2(MCl42-)-Salze (worin XanH+ die protonisierte Form von Xanthin bedeutet und M=Zn(II), Cd(II) oder Hg(II) ist) wurden synthetisiert und mit IR,1H-NMR, TG und DSC untersucht. In diesem Fall liegt keine Koordination des Metalls mit dem Liganden vor, und es bildet sich eine salzartige Struktur aus. Das kationische Proton ist an N(7) lokalisiert. Die thermische Zersetzung dieser Salze erfolgt in zwei Schritten: (i) Dehalogenisierung und (ii) Zersetzung. Dehalogenierungsenthalpien wurden aus DSC-Kurven berechnet.РезюмеСинтезированы и изуч ены с помощью ИК- и ПМР-спектроскопии, а т акже методами ТГ и ДСК соли [XanH+]2[MCl42−], где XanH+ — протонированная форма ксантина, а M — двухвалентные цин к, кадмий и ртуть. В эти х солях металл не образует ко ординационной связи с лигандом, а обр азует солеобразную с труктуру. Протонирование ксан тина происходит по азоту в седьмом положении. Те рмическое разложение солей про исходит в две стадии: дегалоге нирование и разложен ие. Из ДСК-кривых были вычис лены энтальпии реакции дегалогенир ования.

Bromopalladates(II) of xanthine derivatives. Crystal structure of 1,3,8-trimethylxanthinium tribromopalladate(II) monohydrate

Abstract Reaction of PdBr2 in aqueous HBr yielded salts of the type (LH)2[PdBr4] for L = theobromine and theophylline, and (LH)2 [Pd2Br6] for L = caffeine and various 1,3-dimethyl-8-alkylxanthines. Crystals of (1,3,8-trimethylxanthinium)2[Pd2Br6] belong to the monoclinic P21/c space group, with a = 11.343- (2), b = 7.237(1), c = 18.847(4) A, β = 104.26(1)° and Z = 4. The structure was refined on 2439 independent Cu K α reflections to R = 0.046. The unit cell consists of dinuclear [Pd2Br6]2− anions containing two bridging Br ligands, and 1,3,8-trimethylxanthinium cations in which hydrogens are bound to both imidazolic nitrogen atoms. The unit cell contains stacks of trimethylxanthinium cation pairs alternating with [Pd2Br6]2− anions, whereas water molecules form hydrogen bonds with partners in different stacks. The infrared spectra are consistent with the presence of monoprotonated xanthinium cations and [PdBr4]2− or [Pd2Br6]2− ions in all cases. These salts are found to be strongly acidic and to dissociate into the neutral ligands in DMSO solution.

Thermal decomposition of 6-amino-1,3-dimethyl-5-phenylazouracil complexes of Co(II), Ni(II), Cu(II) and Ag(I)

Abstract The thermal behaviour of 6-amino-1,3-dimethyl-5-phenylazouracil complexes of Co(II), Ni(II), Cu(II) and Ag(I) ions was studied by IR, thermogravimetric and differential scanning calorimetric techniques. IR spectroscopy applied to these complexes heated in air allowed the elucidation of the decomposition steps and the nature of the intermediate products. The Cu(II) complexes led to the same products on heating at 225°C [bis(1,3-dimethyl-2,4-dioxo-5-phenylazo-1,2,3,4- tetrahydropyrimidine-6-oxido)copper(II)].

Caffeine complexes of mercury(I): crystal structure of [Hg2(caffeine)2(NO3)2]

Abstract The crystal structure of Hg2(caffeine)2(NO3)2 has been determined by X-ray diffraction methods. It crystallizes in the monoclinic space group C2/c with a=26.969(4), b=5.273(1), c=16.956(4) A, β= 100.89(1)°, V=2368.0(9) A3, Z=4. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R=0.028 for 2404 observed reflections. The crystal contains discrete [Hg2(caffeine)2]2+ ions in which HgHg 2+ ions are linearly bonded to N9. The structure is stabilized by a number of contacts between mercury and nitrate oxygens.