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Research has been conducted on the cyclization-elimination reactions. Results indicate that these reactions have been slower with zinc(II) than with cadmium(II) and that the complexes containing either cyclized or uncyclized ligands have been isolated.

Research describes the reaction of methyl-phenyltin(IV) chloride with thiamine diphosphate and structural characterization of the products formed. Data indicate that an oxygen-capped cationic cluster, a methyltin(IV) derivative, exhibits coordination of thiamine diphosphate through its terminal phosphate group.

Results describe the synthesis and the structural and magnetic characterization of two new copper complexes with 1-phenyl-3,5-dimethylpyrazole along with bromine and chlorine. Data reveal that bromine and chlorine ions change compound structures and bond geometry.

A new approach is proposed for the preparation of ruthenium nitrosyl complexes featuring N-heterocyclic ligands. Characterization of the complexes were conducted through molar conductance measurements, elemental analysis, UV-visible, infrared, electron paramagnetic resonance and proton nuclear magnetic spectroscopies and electrochemical methods. The crystal structure indicates RuII-NO+ moiety exists in the nitrosyl complexes.

A crystalline thiamine-cadmium complex,(CdTCl3)2.2H2O, may be prepared from a mixture of aqueous CdCl2, alkali solution and TCl.HCl. In this compound, the Cd (II) ions are bridged by two N(1'), O(5gamma)-bound thiamines forming a cyclic, centrosymmetric dimer as a distorted trigonal bipyramid. The thiamine ligand is in F conformation having thetaT = 11 degrees and thetaP = 98.3 degrees. No detoxifying effect of thiamine was found in Sprague rats when injected with various regimes of B1 after injection with CdCl2.H2O. It has been postulated that a complex of cadmium chloride and thiamine may be passed from body.

The one-pot synthesis and characterization of fac-[Ru(NO)[Cl.sub.2]([K.sup.3][N.sup.4],[N.sup.8],[N.sup.11](1-carboxypropyl)cyclam)Cl*[H.sub.2]O by reaction of 1-carboxypropyl)cyclam ligand with RuNO[Cl.sub.3] is reported. The complex shows very singular structure, where the N atom of the cyclam ligand that holds the carboxypropyl pendant arm is not coordinated to the ruthenium center resulting in a [K.sup.3] denticity for the substituted cyclam ligand instead of the expected [K.sup.4].

The crystal and molecular structure of [Ru[(DMAP).sub.6]][Cl.sub.2].6[C.sub.3]C[H.sub.2]OH (DMAP = 4-dimethylaminopyridine) is studied by using X-ray diffraction method. The density functional theory (DFT) calculations have shown that in {[Ru.sup.II][(DMAP).sub.5]} the DMAP ligands have competed for the [pi] electron density of the ruthenium making the fragment a weaker [pi]-donor.

A mixture of pyridoxalrhodanine, triethylphosphinegold(I) chloride and sodium methoxide in methanol has afforded the azacoumarin complex and it is characterized by X-ray diffractometry. The results have indicated that the complex has displayed in vitro antitumor activity than cisplatin against the cisplatin-resistant cell line A2780cis.

The synthesis of the new thiamine diphosphate derivative [SnMe2(HTDP)(H2O)]Cl.H2O, its structures in solid state and in water, and the results of the kinetic experiments are described. The resulting SnMe2-holoen-zyme retains a significant proportion of the catalytic activity of the native enzyme despite the methyl groups on the metal atom.

Research has been conducted on PbPh (sub)2 Cl (sub)2. The authors have investigated the reactions of this complex with such compounds as acetophenone and salilyladehyde, and have presented the results.

The complex fac-[Ru(NO)Cl2(κ³N4,N8,N11 (1-carboxypropyl)cyclam)]Cl · H2O (1-carboxypropyl)cyclam = 3-(1,4,8,11-tetraazacyclotetradecan-1-yI)propionic acid) was prepared in a one pot reaction by mixing equimolar amounts of RuNOCl3 and (1-carboxypropyl)cyclam and was characterized by X-ray crystallography, electrospray ionization tandem mass spectrometry (ESI-MS/MS), elemental analysis, NMR, and electronic and vibrational (IR) spectroscopies. fac-[Ru(NO)Cl2(κ³N4,N8,N11(1-carboxypropyl)cyclam)]Cl · H2O crystallizes in the triclinic, space group P1, No. 2, with unit cell parameters of a = 8.501 (1) Å, b = 9.157(1) Å, c = 14.200(1) Å, α = 72.564(5)°, β = 82.512(5)°, ³ = 80.308(5)°, and Z = 2. The Ru-N interatomic distance and bond angle in the [Ru-NO] unit are 1.739(2) Å and 167.7(2)°, respectively. ESI-MS/MS shows characteristic dissociation chemistry that initiates by HCl or NO loss. The IR spectrum displays a ν(NO) at 1881 cm-1 indicating a nitrosonium character. The electronic spectrum shows absorptions bands at 264 nm (log ε = 3.27), 404 nm (log ε = 2.53), and 532 nm (log ε = 1.88). ¹H and 13C NMR are in agreement with the proposed molecular structure, which shows a very singular architecture where the cyclam ring N (with the carboxypropyl pendant arm) is not coordinated to the ruthenium resulting in a κ³ instead of the expected κ4 denticity. [ABSTRACT FROM AUTHOR]

The complex [SnMe2(HTDP)(H2O)]Cl·H2O, synthesized by reaction between dimethyltin(IV) dichloride and thiamine diphosphate hydrochloride (H3TDPCI) in water, was characterized by X-ray diffractometry and IR and Raman spectroscopy in the solid state, and by electrospray mass spectrometry (ESMS) and NMR spectroscopy (¹H,13C, 31P, 119Sn and inverse-detection ¹H,15N HMBC) in aqueous solution. In the solid state the HTDP- anion chelates the metal via one oxygen atom of each phosphate group [Sn-O = 2.062(3), 2.292(3) Å], and another oxygen atom belonging to the terminal phosphate links the SnMe22+ cations into chains. The tin atom has distorted octahedral coordination involving the trans methyl groups, the above-mentioned diphosphate oxygen atoms, and the oxygen atom of the coordinated water molecule. The thiamine moiety has F conformation. NMR studies suggest that the interaction between the organometallic cation and the HTDP- ligand persists in D2O solution, which is in keeping with the ESMS spectrum showing a peak corresponding to [SnMe2(HTDP)]. Both in the solid state and in solution, the acidic HTDP- proton in the complex is located on the N(1') atom of the pyrimidine ring. The enzymatic behavior of native pyruvate decarboxylase (EC 4.1.1.1, PDC), obtained from baker's yeast, was compared in a coupled assay with that shown by the "SnMe2-holoenzyme" created by incubation of apoPDC with [SnMe2(HTDP)(H2O)]Cl·H2O. The SnMe2-holoenzyme exhibited about 34% of the activity of the native enzyme (with a MichaelisMenten constant of 2.7 µM, as against 6.4 µM for native PDC), so confirming the very low specificity of PDC regarding the identity of its metal ion cofactor. In view of the observed protonation of N(1'), it is suggested that the role of divalent cations in the mechanism of thiamine-diphosphate-dependent enzymes may be not only to anchor the cofactor in its binding site but also to shift the acidic proton of HTDP- from the diphosphate group to N(1'); protonation of N(1') is widely believed to be important for enzyme function, but the origin of the proton has never been clarified. r in the Mechanism of Vitamin-B1-Dependent Enzymes. [ABSTRACT FROM AUTHOR]

Examines the reaction between thiamine diphosphate hydrochloride and methylphenyltin chloride in water. Molecular and crystal structure of the oxygen-capped cluster; Detection of hydrogen-bonded oxygen in nonterminal phosphate.

The complex fac-[Ru(NO)Cl2(kappa(3)N(4),N(8),N(11)(1-carboxypropyl)cyclam)]Cl.H2O (1-carboxypropyl)cyclam=3-(1,4,8,11-tetraazacyclotetradecan-1-yl)propionic acid) was prepared in a one pot reaction by mixing equimolar amounts of RuNOCl 3 and (1-carboxypropyl)cyclam and was characterized by X-ray crystallography, electrospray ionization tandem mass spectrometry (ESI-MS/MS), elemental analysis, NMR, and electronic and vibrational (IR) spectroscopies. fac-[Ru(NO)Cl 2(kappa(3)N(4),N(8),N(11)(1-carboxypropyl)cyclam)]Cl.H2O crystallizes in the triclinic, space group P1, No. 2, with unit cell parameters of a=8.501(1) A, b=9.157(1) A, c=14.200(1) A, alpha=72.564(5) degrees , beta=82.512(5) degrees , gamma=80.308(5) degrees , and Z=2. The Ru-N interatomic distance and bond angle in the [Ru-NO] unit are 1.739(2) A and 167.7(2) degrees , respectively. ESI-MS/MS shows characteristic dissociation chemistry that initiates by HCl or NO loss. The IR spectrum displays a nu(NO) at 1881 cm(-1) indicating a nitrosonium character. The electronic spectrum shows absorptions bands at 264 nm (log epsilon=3.27), 404 nm (log epsilon=2.53), and 532 nm (log epsilon=1.88). (1)H and (13)C NMR are in agreement with the proposed molecular structure, which shows a very singular architecture where the cyclam ring N (with the carboxypropyl pendant arm) is not coordinated to the ruthenium resulting in a kappa(3) instead of the expected kappa(4) denticity.