María D. Couce

Diorganotin(IV)-promoted deamination of amino acids by pyridoxal: SnR2+2 complexes of pyridoxal 5'-phosphate and of the Schiff base pyridoxal-pyridoxamine (PLPM), and antibacterial activities of PLPM and [SnR2(PLPM-2H)] (R = Me, Et, Bu, Ph)

Pyridoxal 5′-phosphate (PLP) and pyridoxal (PL) itself were reacted with diorganotin(IV) derivatives in the presence and absence of aminoacids. With PLP the complexes [SnR 2 (PLP-2H)] (R=Me, Et, Bu) were isolated and characterized by EI and FAB mass spectrometry and by IR, Raman and Mossbauer spectroscopy. Reaction mixtures containing PL, valine or glycine and SnR 2 (OAc) 2 (R=Me, Et) afforded complexes of the form [SnR 2 (PLPM-2H)], where PLPM is the Schiff base formed by condensation of PL and pyridoxamine (PM). PM was presumably formed by transamination between valine or glycine and PL. The PLPM complexes, and their butyl and phenyl analogues, were also synthesized directly by reacting SnR 2 O and PLPM, and were characterized by EI and FAB MS, by IR, Raman, Mossbauer and NMR spectroscopy, and in the case of the methyl and ethyl compounds by single-crystal X-ray diffractometry. Crystals of [SnMe 2 (PLPM-2H)]·H 2 O and [SnEt 2 (PLPM-2H)] consist of molecules in which the ligand is bound to the metal through the O atoms of the two deprotonated phenolic hydroxyl groups and the iminic N atom, and the metal exhibits distorted square pyramidal coordination. Both PLPM and its complexes show intense antibacterial activity against Pseudomonas aeruginosa (ATCC27853), but only the complexes exhibit significant activity against the other four bacterial strains assayed, Staphylococcus aureus , Bacillus subtilis , Escherichia coli and a carbapenem-resistant P. aeruginosa strain.

The crystal structure of the salts [Hthiamine][SnMe2(H2O)Cl3]Cl and [Hthiamine][SnPh2Cl4]H2O: competition between water and chloride for coordination to diorganotin dihalides

Abstract Reaction of thiamine chloride hydrochloride (TCl·HCl) (vitamin B 1 hydrochloride) with SnMe 2 Cl 2 and SnPh 2 Cl 2 in 9:1 v/v ethanol-water afforded the salts (HT)[SnMe 2 (H 2 O)Cl 3 ]Cl ( I ) and (HT)[SnPh 2 Cl 4 ]H 2 O ( II ) respectively. Both compounds were characterized by mass spectrometry and by IR and Raman spectroscopy, and the crystal structures of both were determined by X-ray diffraction. I crystallizes in the monoclinic space group P 2 1 / n ; the thiaminium cation adopts the F conformation, and in the anion the tin atom co-ordinates to two trans C atoms of methyl groups, three Cl atoms and the O atom of a water molecule in a distorted octahedral arrangement. II crystallizes in the triclinic space group P 1 ; the thiaminium cation adopts the S conformation, and there are two kinds of [SnPh 2 Cl 4 ] 2− anion, one placed between two cations with its phenyl groups stacking over their pyridine rings, and the other without a close relationship with any cation. The two Sn atoms lie on a crystallographic inversion centre and have a separation of (0.5, 0.5, 0.0). Several hydrogen bonds are present in both structures, as well as S … O electrostatic interactions in II .

Reaction of the diethyltin(IV) cation with pyridoxine (PN, vitamin B6) in the presence of various anionic species: the crystal structure of [SnEt2(PN–H)]Cl

Abstract Reaction of the diethyltin(IV) cation with pyridoxine (PN, vitamin B6) in 80:20 (v/v) ethanol–water mixtures containing NO3− and Cl−, NO3− and AcO− or Cl− and AcO− ions in various molar ratios was investigated. The compounds [SnEt2(PN–H)]Cl (1), [SnEt2(PN–H)](NO3)·2H2O (2) and [SnEt2(PN–2H)] (3) were isolated. These compounds were characterized by IR, Raman and Mossbauer spectroscopy and EI and FAB mass spectrometry. The structure of compound 1, determined by X-ray diffraction, consists of dimeric [SnEt2(PN–H)]22+ units (in which two bridging-chelating hydrogen pyridoxinate anions link Sn atoms with coordination number five) and hydrogen-bonded Cl− ions. The behaviour of these compounds in DMSO-d6 and DMF-d7 was studied by NMR spectroscopy.

A novel hexanuclear silver(I) cluster containing a regular Ag6 ring with short Ag–Ag distances and an argentophilic interaction

The hexanuclear complex [HQ][Ag(p-mpspa)] (H2-p-mpspa = 3-(4-methoxyphenyl)-2-sulfanylpropenoic acid) was prepared by reacting the precursor [Ag(H-p-mpspa)] with diisopropylamine (Q). The complex was characterized by spectroscopic techniques and the structure was solved by a single crystal X-ray diffraction study. The crystal contains hydrogen-bonded diisopropylammonium cations and [Ag6(p-mpspa)6](6-) anions that are based on a regular Ag6 ring with each S-donor atom of the sulfanylcarboxylate ligand bridging two Ag atoms. The Ag-Ag bond distances, 2.8036(6) Å, are very short and suggest a closed shell d(10)···d(10) argentophilic interaction. To analyze the relative role of this interaction and that of the S-bridging atom the anionic [Ag6(p-mpspa)6](6-) moiety has been studied theoretically at the Hartree-Fock (HF) and 2(nd) order Møller-Plesset perturbation theory (MP2) levels on a very simple [Ag6(SH)6] A model system. A large model system [Ag6(p-mpspa)6](6-)B has also been studied by applying the ONIOM (QM/MM) approach using HF/UFF and MP2/UFF combinations as levels of theory. The six experimentally observed Ag(I)···Ag(I) supported interactions are reproduced when dispersion-type interactions are considered in the theory levels MP2 and ONIOM MP2/UFF for models A and B, respectively. The use of HF and ONIOM HF/UFF levels led to a similar hexanuclear structure but displayed a large hexagonal disposition without argentophilic contacts for both models A and B. The steric hindrance exerted by the ligands did not preclude the formation of argentophilic interactions, as observed experimentally.

Triphenyltin(IV) sulfanylpropenoates: synthesis, crystal structures and antimicrobial activities

Three new triphenyltin(IV) sulfanylcarboxylates with the general formula [Q][SnPh3(L)] (Q = di-isopropylammonium cation; L = tspa, pspa or pyspa, where t = 3-(2-thienyl)-, p = 3-(2-phenyl)-, py = 3-(2-pyridinyl)- and spa = 2-sulfanylpropenoato) have been prepared by reaction of triphenyltin(IV) hydroxide with the corresponding acid in the presence of di-isopropylamine in ethanol. The compounds have been characterized by elemental analysis and mass spectrometry and by IR, Mossbauer and NMR (1H, 13C, 119Sn) spectroscopy. X-ray studies of the crystal structures of [Q][SnPh3(pspa)] and [Q][SnPh3(pyspa)] show that in both compounds the tin atom is coordinated to three phenyl C atoms and to S and one O atom of the ligand L. All three complexes are active against strains of the Gram-positive bacterium Staphylococcus aureus, but are inactive or only slightly active against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Copyright © 2000 John Wiley & Sons, Ltd.

New structural features in triphenylphosphinesilver(I) sulfanylcarboxylates

We investigated the reactions of 1.5 : 1 : 1 mole ratio mixtures of triphenylphosphine, silver nitrate and 3-(aryl)-2-sulfanylpropenoic acids H(2)xspa in chloroform/water, where in the acid nomenclature, spa = 2-sulfanylpropenoato and x = p, Clp, mp, diBr-o-hp or f with p = 3-phenyl-, Clp = 3-(2-chlorophenyl)-, mp = 3-methoxyphenyl-, diBr-o-hp = 3-(3,5-dibromo-2-hydroxyphenyl)- and f = 3-(2-furyl)-. The compounds [Ag(PPh(3))(Hpspa)](1), [(AgPPh3)2(xspa)][x = Clp (2), o-mp (3), p-mp (4), diBr-o-hp (5) and f (6)] and [Ag(PPh3)3(Hfspa)](7) were isolated and all except 7 were characterized by IR, Raman and FAB mass spectrometry and by 1H, 13C and 31P NMR spectroscopy. Compound 6 was also characterized by (13)C CP/MAS, and compounds 1 and 6 by (109)Ag NMR spectroscopy. The crystal structures of 1, 2, 3, 4.(CH3)2CO, 5, 6.(CH3)2CO and 7 were determined by X-ray diffraction. has a supramolecular structure based on hydrogen bonding between dinuclear units, and all the other complexes adopt discrete structures. 2, 3, 4.(CH3)2CO, 5, and 6.(CH3)2CO are tetranuclear, and 7 mononuclear. The tetranuclear complexes contain the eight-membered coordination ring Ag4S2O2 (2, 3, 4.(CH3)2CO, 6.(CH3)2CO) or the twelve-membered ring Ag4(CO2)2S2 (5).

Synthesis and antimicrobial activities of silver(I) sulfanylcarboxylates. Structural isomers with identically or unequally coordinated Ag centers in an Ag4S4 ring.

We have investigated the reactions of silver nitrate and 3-(aryl)-2-sulfanylpropenoic acids [H(2)xspa, x: p = 3-phenyl-, f = 3-(2-furyl)-, t = 3-(2-thienyl)-, py = 3-(2-pyridyl)-] and 2-cyclopentylidene-2-sulfanylacetic acid (H(2)L) in 1 : 1 and 2 : 1 molar ratios. The 1 : 1 molar ratio gave compounds of type [Ag(HL)]; reaction of these compounds with diisopropylamine and NaOH gave [HQ][Ag(L)] (HQ = diisopropylammonium) and Na[Ag(L)] x H(2)O, respectively. These compounds, as well as those of type [Ag(2)(L)] obtained with the 1 : 2 molar ratio, were isolated and characterized by IR and NMR ((1)H and (13)C) spectroscopy. (109)Ag NMR spectroscopy and ESI-MS spectrometry were also used in some cases. The crystal structures of [HQ][Ag(pspa)] (11), in which the presence of structural isomers was detected, and [HQ][Ag(cpa)] (15) were determined by X-ray diffractometry. The antimicrobial activity of the complexes against E. coli, S. aureus, B. subtilis, P. aeruginosa/Resistant P. aeruginosa, and C. albicans was tested.

Synthesis, characterization and cytotoxic activity of complexes of diorganotin(IV) halides with N-methyl-2,2′-bisimidazole

The compounds [SnR2X2(MBIm)] (MBIm=N-methyl-2,2′-bisimidazole; R=Me, Et, Bu, Ph; X=Cl or Br) have been synthesized and characterized by IR, Raman, Mossbauer and NMR spectroscopy, and their capacity to inhibit tumour cell division has been assayed. Measurements of conductivity in acetonitrile show the adducts to behave as non-ionogens in this solvent. The IR, Raman and Mossbauer data suggest that all the complexes have analogous pseudo-octahedral coordination geometries, with the R groups trans and MBIm bidentate. The 1H NMR spectra show the MBIm ligand to be partially dissociated in CDCl3. The most active compounds against the established cell line KB were the butyl derivatives.

Thiazole complexes of diorganotin(IV) dihalides: the crystal structure of dichlorodiphenylbis(thiazole) tin(IV)

Abstract The reaction of thiazole (Tz) with diorganotin(IV) dihalides yielded compounds of type [SnR 2 X 2 (Tz) 2 ] (R = Me, Et, Ph; X = Cl, Br). The structure of dichlorodiphenylbis(thiazole)tin(IV) was determined by X-ray diffraction. The crystals are monoclinic (space group P 2 1 / c ) and consist of discrete trans -SnPh 2 Cl 2 (Tz) 2 units with the metal atom coordinated to two Cl atoms, two phenyl carbons, and the N atoms of two thiazole rings. Mossbauer and IR spectra suggest similar trans-stereochemistry for the other complexes prepared. The behavior of these compounds in solution was studied by conductimetry and NMR techniques.

Synthesis and antimicrobial activities of silver(I) 3-(substituted phenyl)sulfanylpropenoates.

We investigated the reactions of silver nitrate with 3-(substituted phenyl)-2-sulfanylpropenoic acids H(2)L [L=xspa, where spa=2-sulfanylpropenoato and xin{Clp=3-(2-chlorophenyl)-, -o-mp=3-(2-methoxyphenyl)-, -o-hp=3-(2-hydroxyphenyl)-, -p-hp=3-(4-hydroxyphenyl)-, diBr-o-hp=3-(3,5-dibromo-2-hydroxyphenyl)-}] in 1:1 and 2:1 molar ratios. The 1:1 reactions gave compounds of type [Ag(HL)], which reacted with NaOH to afford Na[Ag(L)].xH(2)O (x=1 or 2) and with diisopropylamine to afford [HQ][Ag(L)] (HQ=diisopropylammonium). The 2:1 reactions gave products of type [Ag(2)(L)]. All the new compounds were isolated and characterized by IR spectroscopy, and all except the 2:1 adducts (which were insoluble) were studied by (1)H and (13)C NMR spectroscopy; ESI-MS spectrometry was also used for [HQ][Ag(L)] and Na[Ag(L)].xH(2)O, and the crystal structures of H(2)Clpspa and [HQ][Ag(Clpspa)] were determined by X-ray diffractometry. The antimicrobial activities of the complexes against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa and carbapenem-resistant P. aeruginosa were evaluated and compared with those of Ag(I) complexes with other aryl sulfanylpropenoates or related ligands.