José Sordo

Main group metal complexes of semicarbazones and thiosemicarbazones. A structural review

Abstract The structural aspects of the complexes formed by thiosemicarbazones (TSCs) and semicarbazones (SCs) with the metallic elements of Groups 12, 13, 14 and 15 are surveyed up to 1998. Descriptions of 71 structures containing neutral or deprotonated TSCs and ten with SCs include information on the metal-to-ligand bonds and the coordination behaviour of the ligand. The survey shows that TSCs are very versatile coordination agents with these acceptors.

The crystal structure and hydrolysis equilibrium of triphenyl(2-mercapto-1-methylimidazolato)tin(IV)

Abstract The title compound was prepared from 1-methyl-2(3H)-inidazolinethione and triphenyltin(IV) hydroxide, and its crystal structure was determined by X-ray diffraction. The crystal consists of discrete molecules with the tin atom coordinated to one carbon atom of each of the three phenyl groups and to the sulfur atom of the deprotonated ligand. An SnN interaction [2.920(3) A] slightly distorts the tin coordination geometry from that of a perfect tetrahedron. NMR spectroscopy was used to study the hydrolysis of this compound in CDC13.

Diorganotin(IV) derivatives of salicylaldehydethiosemicarbazone. The crystal structure of dimethyl- and diphenyl- (salicylaldehydethiosemicarbazonato)tin(IV)

Abstract The title compounds have been prepared by reacting the corresponding diorganotin(IV) oxide with salicylaldehyde thiosemicarbazone (H2L). [SnMe2(L)] crystallizes in the monoclinic space group P21/n with a=9.480(3), b=13.532(7), c=10.541(3) A, β=100.33(2)° and Z=4 (R=0.0230, R′=0.0258). [SnPh2(L)] crystallizes in the space group P21/a with a=13.483(8), b=10.078(1), c=15.622(4) A, β=113.66(4)° and Z=4 (R=0.030, R′=0.031). Both complexes consist of molecules in which the bisdeprotonated ligand is O,N,S-bonded and the tin atom exhibits distorted pentacoordination, with small differences between the methyl and phenyl derivatives in bond distances, bond angles and intermolecular hydrogen bonds. The spectral properties of the complexes (IR, Mossbauer and 1H, 13C and 119Sn NMR spectra) are discussed in the light of this structural information.

Structural aspects of the coordination chemistry of organothallium(III) and organomercury(II) derivatives

Abstract This review surveys the main structural aspects of the coordination chemistry of mono-, di- and triorganothallium(III) and mono- and diorganomercury(II) complexes. It covers all organothallium(III) derivatives reported up to the end of 1997 and the organomercury compounds reported between 1993 and 1997. Structures are classified primarily by coordination number and secondarily by kernel complexity.

Crystal and molecular structure of spirobicyclic bis(tetraphenyldithioimidodiphosphinato)lead(II), [Pb(SPPh2)2N];2], containing a new inorganic (carbon-free) PbS2P2N chelate ring and Pb(η6-C6H5) interactions

Abstract The title compound, [PbSPPh2)2N];2], was obtained by reacting potassium tetraphenyldithioimidodiphosphinate with lead(II) acetate. X-ray diffraction analysis reveals an unsymmetrical (anisobidentate) coordination of the chelating ligands, indicated by non-equal PbS interatomic distances [2.695(4) and 2.943(4) A] and some PN and PS bond length alternation within the two NP2S2Pb rings that form the spirobicyclic complex. The lead coordination is supplemented by two additional Pb(η6-C6H5) interactions with two phenyl groups. If these interactions are considered, the geometry of the coordination sphere may be described as distorted octahedral.

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.

Synthesis and spectroscopic properties of diorganotin(IV) derivatives of 2,6-diacetylpyridine bis(thiosemicarbazone). Crystal structure of diphenyl{2,6-diacetylpyridine bis(thiosemicarbazonato)}tin(IV) bis(dimethylformamide) solvate

The reaction of the title ligand (H2DAPTSC) with SnR2O (R=Me, Ph) in DMF afforded the complexes [SnR2(DAPTSC)]. The phenyl derivative crystallizes as [SnPh2(DAPTSC)]·2DMF in the P21/n space group, with lattice constants: a=9.753(1), b=18.962(1), c=17.923(3) A, β=97.93(1), Z=4 and R=0.035. The molecular complex is pentagonal bipyramidal, with the five donor atoms of the ligand in the pentagonal plane and the two phenyl groups in the axial positions. A comparative study based on the spectral properties (IR, Mossbauer and 1H, 13C and 119Sn NMR spectroscopy) of the two complexes suggests a similar structure for [SnMe2(DAPTSC)].

DIORGANOTIN(IV) COMPLEXES OF PYRIDOXAL THIOSEMICARBAZONE : SYNTHESIS, SPECTROSCOPIC PROPERTIES AND BIOLOGICAL ACTIVITY

The complexes [SnR2(L)] (R = Me, Et, Bu, Ph; H2L = pyridoxal thiosemicarbazone) have been prepared and characterized. In the light of the spectral properties of the complexes in the solid state (IR, mass, Mössbauer) the bideprotonated thiosemicarbazonato anion is O(phenolic)-, N(3)-, S-bonded to the tin atom which probably has trigonal bipyramidal coordination with N(3) atom and R groups occupying equatorial positions. NMR ( 1H, 13C and 119Sn) data in CDCl3 or DMSO-d6 suggest that this coordinative picture remains in these solutions. The ethyl, butyl and phenyl derivatives suppress proliferation of Friend erithroleukaemia cells (FLC). Of the pyridoxal thiosemicarbazone complexes so far evaluated. [SnBu2(L)] and [SnPh2(L)] showed the lowest thresholds for inhibition of FLC proliferation. The effects of these compounds on DMSO-induced differentiation of FLC, DNA synthesis and reverse transcriptase were also assayed.

Synthesis, structure, and spectroscopic properties of acetato (dimethyl) (pyridine-2-carbaldehydethiosemicarbazonato)tin(IV) acetic acid solvate, [SnMe2 (PyTSC)(OAc)].HOAc. Comparison of its biological activity with that of some structurally related diorganotin(IV) bis(thiosemicarbazonates)

The synthesis, X-ray structure, behavior in solution, and biological properties of the complex [SnMe2(PyTSC)(OAc)].HOAc (HPyTSC = pyridine-2-carbaldehydethiosemicarbazone) are reported. The tin atom of this complex is coordinated to an N,N,S-tridentate PyTSC- anion, to a monodentate acetate ion, and to the two methyl groups in an approximately pentagonal bipyramidal environment with a vacant equatorial position. The complex partially evolves in DMSO and in DMSO/CHxCl4-x (X = 1, 2) mixtures, giving HPyTSC and SnMe2(OAc)2. [SnMe2 (PyTSC)(OAc)].HOAc, [SnMe2(DAPTSC)], and [SnPh2(DAPTSC)].2DMF (H2DAPTSC = 2,6-diacetylpyridine bis(thiosemicarbazone)) all suppress proliferation of Friend erythroleukaemia cells (FLC). DMSO-induced differentiation of FLC is slightly suppressed by [SnMe2(DAPTSC)] and is unaffected by [SnPh2(DAPTSC)].2DMF and [SnMe2(PyTSC)(OAc)].HOAc.

Reaction of bromopentacarbonylrhenium(I) with ferrocenylcarbaldehyde thiosemicarbazones: the first X-ray diffraction studies of metal carbonyl complexes containing bidentate thiosemicarbazone ligands

Abstract The reactions of [ReBr(CO) 5 ] with ferrocenylcarbaldehyde thiosemicarbazones HL with different groups attached to the amide nitrogen (R=H, Me, Ph) yielded complexes [ReBr(CO) 3 (HL)] ( 1 ) in which, according to X-ray studies of 1a ·{(CH 3 ) 2 CO} and 1b ·1/2{CH 2 Cl 2 }, the thiosemicarbazone is N , S -bidentate and the geometry around the metal fac -octahedral. Compounds of formula [ReL(CO) 3 ] 2 ( 2 ) were then prepared by reaction of the corresponding adduct 1 with NaOMe in acetone. A complex of formula [ReL 2 (CO) 3 ] 2 ( 2b ′) was also obtained as a dissolvate by slow concentration of a solution of 1b in acetone. Single crystals of 2a and 2b obtained from the mother liquors are composed of centrosymmetric dimers formed by ReSRe bridges, where S is the thiolic sulfur of an N , S -bidentate thiosemicarbazonato ligand. Although 2b ·2{(CH 3 ) 2 CO} and 2b ′·2{(CH 3 ) 2 CO} have similar co-ordination spheres, they differ as regards the configuration of the thiosemicarbazonato ligand about the azomethine bond and certain bond lengths (notably ReN); it seems likely that the configuration of L 2− determines how close the rhenium can approach the N atom of the ligand, and hence the delocalization of the π electrons in the CNN fragment of the thiosemicarbazide chain. The mass, IR and UV–vis spectra of the complexes, and their electrochemical behavior, are also discussed.