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1

Reactions of the First Cisplatin Hydrolytes cis-[Pt(15NH3)2(H2O)Cl]+ with L-Cysteine

Hadi S., Appleton T. G.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 3

437-443

EN

The interactions of cis-[PtCl(15NH3)2(H2O)](NO3) (2) with L-cysteine (H2cys) was investigated in aqueous solution. In this reaction, the polymeric solid was not formed and the ammine liberation was slower than the similar reaction for cis-[Pt(15NH3)2(H2O)2](NO3) (3). It is also observed that although in the reactions of 2 with a variety of thiols gave different ultimate product in each reaction, initially the only product observed was a platinum(II) species with chloride and the thiolate ligand bound monodentate through sulphur. In this reaction, after the formation of a species with thiolate bound monodentate cis-[PtCl(15NH3)2(Hcys-S)] (7), this initial product was then converted to some other complexes, trans-[PtCl(15NH3)(Hcys-S)2] (8), cis-[PtCl(15NH3)(Hcys-S)2] (9) and cis-[{Pt(15NH3)2Cl}2(Hcys- -S)]2+ (10). Unlike the reactions of 2 and 3 with other thiols, the bis (thiolate) platinum(II) and dinuclear sulphur-bridged complexes were not formed in solution.

2

Application of 15N NMR Spectroscopy to Determine Coordination Sphere Geometry in Pd(II), Pt(II), Pt(IV), Co(III) and Rh(III) Complexes with Azines

Pazderski L.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 7

1241-1253

EN

The comparison of 15N NMR spectral data for Pd(II), Pt(II), Pt(IV), Co(III) and Rh(III) complexes with simple azines, such as pyridine (py), 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen) and their alkyl or aryl derivatives (2pic, 3pic, 4pic = 2-, 3-, 4-picoline, i.e. 2-, 3-, 4-methyl-py; 2,6lut, 3,5lut = 2,6-, 3,5-lutidine, i.e. 2,6-, 3,5-dimethyl-py; 2,4,6col = 2,4,6-collidine, i.e. 2,4,6-trimethyl-py; 2ppy, 3ppy, 4ppy = 2-, 3-, 4-phenyl-py; 4-tert-butyl-py; 4,4'-dmbpy = 4,4'-dimethyl-bpy; 4,4'-dpbpy = 4,4'-di phen yl-bpy; 4,7-dmphen = 4,7-dimethyl-phen; 4,7-dpphen = 4,7-di phen yl-phen), as well as isoquinoline (isoquin) and 2,2'-biquinoline (bquin) exhibits that 15N NMR coordination shifts, defined as differences between 15N chemical shifts of the same nitrogen in the complex and ligand molecules (Delta coord 15N = delta compl 15N – delta lig 15N ), are, for a given central ion, noticeably dependent on the type of anauxiliary ligand in the trans position. Particularly, absolute magnitudes of Delta coord 15N (| Deltacoord 15N |) decrease in the order of nitrogens opposite to donor atoms N > Cl >> C, what allows to distinguish and assign various geometric isomers of the concerned complexes. The above dependencies were applied to re-determine the geometry of various isomers of some previously reported Pd(II) and Pt(II) chloride complexes with 1,2,4-triazolo-[1,5a]-pyrimidines.

3

NMR Studies of Tautomerism and Protonation Patterns in Bis(6-purinyl) Disulfide and Ionic Forms of 6-Mercaptopurine

Pazderski L., Toušek J., Sitkowski J., Kozerski L., Szłyk E

Polish Journal of Chemistry

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2007

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Vol. 81, nr 2

193-210

EN

1H-13C and 1H-15N HMBC-NMR spectroscopy was applied to study tautomerism and the protonation patterns in 6-mercaptopurine (6mpH) derivatives: bis(6-purinyl) disulfide ((6puS)2), 6-mercaptopurinium cation (6mpH2 + ) and purine-6-thiolate anions (6mp–, 6mp-deH2–). 1H, 13C, 15N resonances were assigned and the respective delta 1H, delta 13C, delta 15N chemical shifts as well as JHC, JHN coupling constants determined. Quantum-chemical NMR calculations by GIAO method (B3LYP/6-31G**//RHF/6-31G*) allowed to evaluate the ratio of N(1), N(3), N(7), N(9)H : N(1), N(3), N(7)H, N(9) tautomeric forms for the DMSO-solvated (6puS)2 molecules as ca. 9:1. The existence of “semi-protonated” 6mpHźH3O+ species, intermediate between 6mpH and 6mpH2 + , and readily oxidized to (6puS)2 was suggested in the DMSO-d6 + HCl solution. Further hydrolysis and oxidation of the formed disulfide lead to the derivatives of purine-6-sulfenic and purine-6-sulfinic acid.

4

15N NMR Coordination Shifts in Transition Metal Chloride Complexes with Azines versus Type of Central Ion

Pazderski L.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 7

1083-1093

EN

15N NMR coordination shift is the difference between the 15N chemical shift of the concerned nitrogen atom in the complex and ligand molecules (Delta coord 15N =delta compl 15N - delta lig 15N ). Themeasurements, convenient for complexes with diamagnetic transition metal ions, allow to determinemetallation siteswithin potentially ambidentateN-donor heterocycles. In case of azines, the 15N coordination shifts of pyridine-type nitrogens are usually negative, i.e. the shielding is observed. Variable low-frequency 15N coordination shifts (ca. 70-140 ppm) were noted for a number of chloride complexes of Pd(II), Pt(II), Au(III), Pd(IV), Pt(IV), Co(III), Rh(III) and Zn(II) with pyridine, 2,2'-bipyridine, 1,10-phenanthroline, 2,2'-biquinoline, purine and 1,2,4-triazolo-[1,5a]-pyrimidine(s). Some dependencies between the magnitude of the shielding effect and such features of the concerned complex as the type of central ion, its electron configuration (oxidation state) and the coordination sphere geometry were discussed.

5

Investigation of Some Intramolecular Hydrogen Bonds by Nitrogen Magnetic Resonance Methods

Stefaniak L.

Polish Journal of Chemistry

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1999

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vol. 73 nr 1

173-180

EN

It was shown that nitrogen NMR is a powerful tool in the studies of different types of hydrogen bridges (NHN)*, (NHN)-, (NHN), and (NHO). Some of the NMR parameters, originally proposed by us, provide information about charge redistribution and the extent of proton transfer. The character of hydrogen bonds depend upon solvent, temperature and the physical phase. The results of studies in the solid state using the 15N NMR CP MAS method were also discussed.

6

FT-IR and NMR stedies of proton sponge character of Cis-1,2-bis(diethylaminomethyl)cyclohexane

Brzezinski B., Grech E., Klimkiewicz J., Schroeder G., Stefaniak L., Urjasz H.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 2

284-291

EN

Cis-1,2-bis(diethylaminomethyl)cyclohexane (DEAMCH) was synthesized and its pK-a values in acetonitrile were measured. Dual behevioral of DEAMCH was observed in the reaction with various acids: HClO4, 4-tert-butylphenol, 4-cyanophenol and pentachlorophenol (PCP) in acetonitrile and acetone-d-6 solutions, respectively, when studied by FT-IR as well as (1)H, (13)C and (15)N NMR spectroscopy. An intramolecular NHN(+) hydrogen bond was found in 1:1 complex of DEAMCH with HClO4 in solution. This hydrogen bond was, however, weaker than those previously observed in other protonated proton sponges. In complexes of DEAMCH with 4-cyanophenol both NHN(+) intramolecular hydrogen bond and structurally symmetrical intermolecular homoconjugated (OHO)(-) hydrogen bonds were formed. These properties of DEAMCH demonstrate its proton sponge like character. On the other hand, in complexes of DEAMCH with more acidic phenol such as PCP intermolecular hydrogen-bonded complexes are formed, in which the OH protons are localized at the amino groups. For these O(-)...HN(+) hydrogen bonds a strongly asymmetrical double minimum proton potential with the well at the N atom is present, characteristic of complexes having no proton sponge like character.