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

Salas-Peregrín, J.M.; Colacio-Rodríguez, E.; Romero-Molina, M.A.; Sanchez‐Sanchez, Maricruz

doi:10.1016/0040-6031(83)80338-4

Cited by 24 publications

(9 citation statements)

References 12 publications

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“…Yield: 370 mg, 54%. 1 trans-Dichloro bis(1,3,7-trimethyl-9-benzylxanthine-8-ylidene) palladium(II) (6) 1,3,7-trimethyl-9-benzylxanthinium bromide (3a, 91 mg, 0.25 mmol) was suspended in THF (1.5 mL), and a solution of potassium tertbutoxide (28 mg, 0.25 mmol) in THF (0.5 mL) was slowly added at room temperature. The mixture was stirred at room temperature for 3 h and filtered to eliminate KBr, and a brown solution was obtained.…”

Section: Methodsmentioning

confidence: 99%

“…Also, the coordination chemistry of the xanthine derivatives toward palladium(II) was investigated and contrasted with their unmodified counterparts [2][3][4][5][6][7][8], determining if the N(1,7) or C (8) hapticity is favored. In addition, a theoretical study of the acidity-basicity and orbital energies of each xanthine, 1-3, was performed, observing a match between theoretical results and the experimental evidence in the modification of these methylated xanthines and their coordination chemistry toward palladium.…”

Section: Introductionmentioning

confidence: 99%

“…In this sense, several efforts have been made to study their coordination chemistry toward ''essential metals'' [3] and their interaction with transition metals [3][4][5][6][7][8]. For instance, Williams [2] et al reported an analog to cis-platin with caffeine, Pt(caff) 2 Cl 2 , and there are reports in which the thermal behavior of these xanthines under physiological conditions has been studied [3][4][5][6]. Also, Taube and coworkers [7] proposed a C(8) coordination to ruthenium in the unmodified caffeine and theobromine ligands, and a mixed N-C, coordination fashion in theophylline.…”

Section: Introductionmentioning

confidence: 99%

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Studies on the coordination chemistry of methylated xanthines and their imidazolium salts. Part 1: benzyl derivatives

Landaeta

Rodríguez-Lugo

Rodríguez-Arias

et al. 2009

Transition Met Chem

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New imidazolium salts derived from the natural methylated xanthines theophylline, theobromine and caffeine, namely 1,3-dimethyl-9-benzylxanthinium bromide (tphBzBr, 1a), 3,7-dimethyl-9-benzylxanthinium bromide (tbrBzBr, 2a) and 1,3,7-trimethyl-9-benzylxanthinium bromide (caffBzBr, 3a), are reported. Also, the disubstituted analog of 1a, 1,3-dimethyl-7,9-dibenzylxanthinium bromide (tphBz 2 Br, 1a 0 ) was identified and characterized by NMR. The coordination chemistry of ligands 1a-3a toward palladium, and some theoretical aspects of the unmodified theophylline, theobromine and caffeine are studied. Our results prove that the theophylline derivative has the thermodynamic tendency to form N-bonded species, even when an equilibrium between the Pd-NHC and the ''theophyllinate'' was observed spectroscopically, due to the anisotropy of the NHC ligand. To confirm the Ncoordination, the solid state structure of the new ''theophyllinate'' species PdBr 2 (tphBz-H) 2 (4), derived from 1a, was determined by X-ray diffraction. The analog with theobromine, ligand 2a, coordinates to palladium via N1, in an analogous manner to 1a, and a mixture of the cis/trans isomers of its palladium complex is obtained. On the other hand, since there is no possibility of N-coordination in 3a, this caffeine derivative forms a Pd-NHC compound after deprotonation with a strong base. Both the theoretical results and the experimental evidence are in accordance, in terms of the predicted coordination sites or possibility of modification of the selected methylated xanthines to obtain new ligands.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Studies on the coordination chemistry of methylated xanthines and their imidazolium salts. Part 1: benzyl derivatives

Landaeta

Rodríguez-Lugo

Rodríguez-Arias

et al. 2009

Transition Met Chem

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“…A very interesting field for the use of these methods is the investigation of the decomposition of these substances in the solid phase, and determination of the corresponding thermodynamic and kinetic parameters and the mechanism of the investigated process. Attention has recently also been paid to the thermal investigation of purines [6] and metal complexes of the derivatives of 6-amino-5-nitrosouracils [7].…”

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confidence: 99%

Thermal behaviour of 1,3-dimethyl-4-alkylamino-5-nitrosouracils

Králik

Gondová

Štibrányi

1986

Journal of Thermal Analysis

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“…The synthetic conditions used for the preparation of the Pd(II) complexes were the same as those employed in a previous work for analogous purine derivative complexes [25]. In all cases a yellow precipitate was formed, which was filtered off, washed successively with water and ethanol and dried with ether.…”

mentioning

confidence: 99%

Thermal studies on Ni(II), Cu(II) and Pd(II) complexes of 6-amino-5-formyluracil and its N-methyl derivatives

Garcia-Megias

Colacio-Rodríguez

Garcı́a-Rodrı́guez

et al. 1987

Journal of Thermal Analysis

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The thermal behaviour of 6-amino-5-formyluracil (HFU), 6-amino-1-methyl-5-formyluracil (I-HFU), 6-amino-3-methyl-5-formyluracil (3-HFU) and 6-amino-1,3-dimethyl-5-formyluracil (HDFU) is described. Only HDFU is shown to contain crystallization water. Dehydration and fusion enthalpy values have been calculated from the DSC curves. Likewise, the thermal behaviour of new complexes obtained by reaction between the above pyrimidine derivatives and Ni(II), Cu(II) and Pd(II) ions is reported.The importance of the interactions of metal ions with pyrimidine and purine is now well recognized [1-6]. Most metal complexes of this type are studied principally with spectroscopic techniques and X-ray diffraction methods [7][8][9][10][11][12][13].By contrast, studies reporting the thermal behaviour of these complexes are scanty. For this reason and in connection with our studies on the synthesis, characterization and thermal behaviour of derivatives of biological importance [14][15][16][17][18][19][20][21][22], we describe here the thermal behaviour of tJour pyrimidine derivatives, 6-amino-5-formyluracil (HFU), 6-amino-l-methyl-5-formyluracil (1-HFU), 6-amino-3-m~thyl-5-formyluracil (3-HFU) and 6-amino-l,3-dimethyl-5-formyluracil (HDFU), and the new Ni(II), Cu(II) and Pd(II) complexes of these pyrimidine derivatives.

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

Cited by 24 publications

References 12 publications

Studies on the coordination chemistry of methylated xanthines and their imidazolium salts. Part 1: benzyl derivatives

Studies on the coordination chemistry of methylated xanthines and their imidazolium salts. Part 1: benzyl derivatives

Thermal behaviour of 1,3-dimethyl-4-alkylamino-5-nitrosouracils

Thermal studies on Ni(II), Cu(II) and Pd(II) complexes of 6-amino-5-formyluracil and its N-methyl derivatives

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