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New palladium(II) complexes have been synthesized by the reaction of Pd(II) with 2-formylpyridine-4-Nethyl-thiosemicarbazone, HFo4NEt, 1. The complexes [Pd(Fo4NEt)Cl], 2, [Pd(H2Fo4NEt)(Fo4NEt)Cl2], 3 and [Pd(Fo4NEt)2], 4 have been characterised by elemental analyses and spectroscopic studies. The crystal structure of the complex [Pd(H2Fo4NEt)(Fo4NEt)Cl2], 3 and the protonated ligand [(H2Fo4NEt)Cl], 5 have been solved by single-crystal X-ray diffraction. The cytotoxic activities of 1–4 have been evaluated for antiproliferative activity in vitro against the cells of three human cancer cell lines: MCF-7 (human breast cancer cell line), T24 (bladder cancer cell line), A-549 (non-small cell lung carcinoma) and a mouse L-929 (a fibroblast-like cell line cloned from strain L). The compound 3 display IC50 values in a μM range better than that of the antitumor drug cis-platin against MCF-7 and T-24 cell lines and is considered as agent with potential antitumor activity candidates for further stages of screening in vitro and/or in vivo.

The synthesis and spectral characterization of novel neutral and cationic organotin complexes with pyruvic acid thiosemicarbazone, H2pt (1), [SnPh2(pt)] (2), [SnMe2(Hpt)(H2O)]Cl (3) and [SnPh2(Hpt)(H2O)]Cl (4) are reported. The crystal structure of the complexes [SnPh2(pt)] (2) and [SnMe2(Hpt)(H2O)]Cl (3) have been solved by single-crystal X-ray diffraction. The crystal structure of complex 2 showed that the ligand is doubly deprotonated at the oxygen and amide nitrogen atoms and is coordinated to the SnPh2 fragment via two five-membered chelate rings. The monomers of 2 are linked through intermolecular hydrogen bonds of C−H–O type and through π−π intermolecular interactions. The crystal structure of [SnMe2(Hpt)(H2O)]Cl (3) showed that the ligand is mono-deprotonated at the oxygen atom and is coordinated to the SnMe2 fragment via two five-membered chelate rings. The counter ion chloride is participated in intermolecular hydrogen bonds. An extended network of intermolecular hydrogen bonds leads to aggregation and a supramolecular assembly. The IR and NMR spectroscopic data of the complexes are reported. The in vitro cytotoxic activity has been evaluated against the cells of three human cancer cell lines: MCF-7 (human breast cancer cell line), T-24 (bladder cancer cell line), A-549(non-small cell lung carcinoma) and a mouse L-929 (a fibroblast-like cell line cloned from strain L). The most active of all was found the diorganotin complex 2. The cytotoxic activity shown by these compounds against all these cancer cell lines indicates that coupling of 1 with R2Sn(IV) metal center result in metallic complexes with important biological properties and remarkable cytotoxic activity, since they are display IC50 values in a μM range the same or better to that of the antitumor drug cisplatin. Compound 2 is considered as agent with potential antitumor activity, and can therefore be candidate for further stages of screening in vitro and/or in vivo.

The reactions of Li2PdCl4 and Na2PtCl4 with pyridine-2-carbaldehyde thiosemicarbazone, HPyTsc, afforded the complexes [Pd(PyTsc)Cl], [Pd(PyTsc)2] and [Pt(PyTsc)Cl], [Pt(PyTsc)2]. The new complexes have been characterized by elemental analyses and spectroscopic studies. A crystal structure of [Pd(PyTsc)Cl] shows that the anion of PyTsc coordinates in a planar conformation to the central palladium(II) through the pyridyl N, azomethine N and thiolato S atoms. The planar molecules are linked into polymeric chains by N–H··N and N–H··S hydrogen bonding. The protonation constants of the ligand, Ka1 and Ka2, were determined by spectrophotometry and the logarithms of their values were found to be equal to 11.58±0.05 and 3.94±0.02 respectively. Correlation of the antitumor activity of these complexes to the structure and to reduction potential is reported. The compounds [Pt(PyTsc)2] and [Pd(PyTsc)2] were found to exhibit the higher in vivo antitumor activity and the lower cytotoxicity.

Reaction of Li2PdCl4 with 2-acetyl- and 2-formylpyridine 3-hexamethyleneiminylthiosemicarbazones, HFohexim and HAchexim, respectively, affords the complexes [Pd(Achexim)Cl] and [Pd(Fohexim)Cl]. [Pd(Fohexim)Cl] crystallizes in the triclinic space group P 1 with a=7.9447(17) A, b=9.6402(13) A, c=10.3739(18) A, α=79.128 (12)°, β=75.104(15)° and γ=75.558(14)°. Crystals of [Pd(Achexim)Cl] are monoclinic, space group P2(1)\n, with four formula units in a unit cell of dimensions a=7.2243(7) A, b=9.6402(13) A, c=24.937(3) A, and β=104.048(9)°. Anions of HFohexim and HAchexim coordinate in a planar conformation to a central palladium(II) via the pyridyl nitrogen, azomethine nitrogen and thiolato sulfur atoms. The complexes have been characterized by spectroscopic techniques (IR and 1H NMR). The protonation constants of HFohexim, Ka1=11.83±0.01 and Ka2=3.70±0.02, were determined spectrophotometrically.

Some new palladium(II) complexes of 2-acetylpyridine N(4)-propyl- and N(4)dipropyl- and 3-hexamethyleneiminylthiosemicarbazones with potentially interesting biological activity were described. The thiosemicarbazones and their palladium(II) complexes have been characterized by spectroscopic, and electrochemical techniques. The protonation constants of HAc4P Ka1 and Ka2, were determined by spectrophotometry and the pK1a and pKa2 values are equal to 12.23 ±0.02 and 4.11 ±0.02. The antifungal properties and the effect selected compounds on DNA synthesis of P388 and L1210 cell cultures is reported.

Anions [loss of N(3) hydrogen of 2-acetylpyridine N(4)-dimethylthiosemicarbazone (HAc4DM)] coordinate in a planar conformation to a central palladium(II) through the pyridyl nitrogen, azomethine nitrogen and thiolato sulfur atoms. The fourth coordination site is occupied by either a bromo, chloro or a second Ac4DM ligand bonding via its thiolato sulfur atom. A crystal structure of [Pd(Ac4DM)Br] shows it to be planar, while the structure of [Pd(Ac4DM)2] has the unusual coordination of the two anions bonding differently to the palladium centre. Spectral and structural similarities and differences between these and related nickel(II) and copper(II) complexes are considered.

The reactions of ZnCl2, CdCl2 and Hg(NO3)2 · H2O with deprotonated diclofenac (L) were studied in aqueous solutions. Complexes of the formulae [Zn(L)2(H2O)], [Cd(L)2(H2O)], [HgL2] and (Cd2(H2O)(C2H5OH)2(L)4]n were isolated and characterized as solid products by elemental analyses and spectral (IR, 1H NMR) and thermal studies. The crystal structure of the complex [Cd2(H2O)(C2H5OH)2L4]n was also solved. The central feature of the macromolecule is a dinuclear moiety. Distorted octahedral coordination at Cd(1) is completed by oxygen atoms from one molecule of water, two molecules of C2H5OH, two oxygen atoms from one chelating ligand with a monoatomic bridging oxygen that bridges the atoms Cd(2)Cd(I) = 4.490(1) A and one oxygen from a bidentate bridging carboxylato group that bridges the atoms Cd(1)Cd(2) = 4.300(1) A. The geometry at Cd(2) is that of a distorted square pyramid with oxygen atoms from one chelating and one monodentate carboxylato group and the monoatomic bridging oxygen atom occupying equatorial positions. The apical site of the square pyramid is occupied by the oxygen atom of the bidentate briding carboxylato group. The crystal structure of the diclofenac acid is also reported.

Complexes of palladium(II) with pyrimidine-2-thione and the thiolate anion were synthesized and characterized. The complexes were prepared in methanolic or aqueous media. The neutral ligand acts as monodentate and exhibits S-coordination in acidic medium or in methanolic solution. In neutral and basic media the thiolate anion of pyrimidine-2-thiol exhibits S,N-ligation through the ring nitrogen and exocyclic sulphur atoms, in the production of an asymmetric, four-membered, chelated ring.