Transfer of the chelating ligands in the systems [LAuCl2]+-[PdCl4]2−: Synthesis and structure of the salt (NH4)0.20[(Bipy)AuCl2]1.04[(Bipy)PdCl2]0.96[AuCl4]0.76[PdCl4]0.24

The formation of binary complex salts containing gold(III) in the cation and palladium(II) in the anion in the systems [(Bipy)AuCl₂]⁺-[PdCl₄]^2? occurs by transfer of the N,N-electron-donating chelating ligand bipyridine and the chloride ligands between the gold-containing cation and the palladium-containing anion. The resulting neutral salt [(Bipy)PdCl₂] crystallizes together with the anion [AuCl₄]^? from acetonitrile-water (1 : 1-1 : 2, v/v) to give the complex salt (NH ₄ ⁺ )_0.20[(Bipy)AuCl ₂ ⁺ ]_1.04[(Bipy)PdCl₂]_0.96[AuCl ₄ ^? ]_0.76PdCl ₄ ^2? ]_0.24 with a total Au : Pd ratio of 3 : 2. The ammonium cation is formed from acetonitrile upon its hydrolysis most likely catalyzed by Pd complexes. Quantum-chemical calculations were performed to study the transfer of the chelating ligand theoretically.     

Distribution of ligands in polynuclear palladium complexes: DFT study of isomerism of Pd4(L)4(RCO2)4 (L = CO,CH2, NO) complexes

Structural isomerism of the Pd₄(L)₄(RCO₂)₄ (L = CO, CH₂, NO; R = CC1₃, CF₃, CH₃) complexes was studied in the framework of the density functional theory (DFT). Among the Pd₄(CO)₄(RCO₂)₄ and Pd₄(CH₂)4(RCO₂)₄ complexes the most stable were the isomers with alternate coordination of pairs of carbonyl and carboxylate ligands on the sides of a planar rectangular metal core. The isomers with the pairwise coordination of NO/RCO₂ on one side of the metal core are the most stable between the Pd₄(NO)₄(RCO₂)₄ complexes. The features of mutual coordination of ligands in polynuclear complexes of palladium are clarified using the obtained results.

     

Bromo dimethyl sulfoxide osmium(II) complexes. Molecular structure of cis,fac-[OsBr2(dmso-S)3(dmso-O)]

Bromo dimethyl sulfoxide osmium(II) complexes were synthesized: trans-[OsBr₂(dmso-S)₄] (1) was obtained by the reaction of K₂[OsBr₆] with DMSO in the presence of SnBr₂ at 100°C and cis,fac-[OsBr₂(dmso-S)₃(dmso-O)] (2) was prepared by thermal isomerization of 1 in a DMSO solution at 150°C. The coordination mode of DMSO molecules was determined by IR and ¹H and ¹³C NMR spectroscopy. X-ray diffraction analysis showed that compound 2 crystallizes in the monoclinic system, space group P2₁/n; a = 8.4711(5) Å, b = 27.7876(15) Å, c = 8.5569(5) Å, β = 115.7110(10)°; Z = 4. The coordination polyhedron of osmium is a distorted octahedron; the osmium environment is formed by two cis-arranged bromine atoms and three fac-S-coordinated and one O-coordinated DMSO molecules. The interconversion of complexes in solutions was studied by UV/Vis and ¹H and ¹³C NMR spectroscopy. In chloroform and DMSO, complex 2 isomerizes to cis-[OsBr₂(dmso-S)₄] and (in the light) to 1. The complexes trans-[OsX₂(dmso-d₆)₄], where X = Cl, Br, were isolated from DMSO-d ₆ and characterized by the IR spectra.     

NO-disproportionation, promoted by Pd-cluster: formation and X-ray structure of Pd8(micro-CO)4(micro-OOCCMe3)8[micro-N(=O)O-]4

Interaction of Pd-clusters [Pd(CO)(OCOR)](n) with NO was investigated, these Pd-clusters were found to promote the NO disproportionation into N(2) and NO(2)(-) in mild conditions; an eight-nuclear palladium cluster Pd(8)(micro-CO)(4)(micro-OOCCMe(3))(8)(micro-NO(2))(4) with a new type of structure and an uncommon set of ligands was characterized by X-ray diffraction analysis.     

Interaction of polynuclear palladium (I) carbonyl carboxylates with gaseous NO: X-ray structure of eight-nuclear clusters Pd8(μ-CO)4(μ-OOCR)4[μ-N(O)O–]4

The reaction of palladium carbonyl carboxylates Pd₆(CO)₆(RCOO)₆ with gaseous nitrogen monoxide was investigated. These clusters were found to promote the NO disproportionation into N₂ and NO₂ under mild conditions. The reaction is accompanied with the oxidation of coordinated carbon monoxide. These processes result in unusual eight-nuclear palladium carboxylate clusters Pd₈(CO)₄(NO₂)₄(RCOO)₈.     

Palladium acetate complexes with morpholine and 4-methylmorpholine. The structure of Pd(C4H9ON)2(OAc)2 · 2H2O

Methods for the synthesis of new palladium(II) acetate complexes [L₂Pd(OCOCH₃)₂], where L is N-coordinated morpholine (C₄H₉ON) or 4-methylmorpholine (C₅H₁₁ON), have been developed. The structure of the complex (C₄H₉ON)₂Pd(OAc)₂ · 2H₂O (1) has been established by X-ray diffraction. The crystals of 1 are monoclinic (C₁₂H₂₆O₈N₂Pd, M = 434.76), space group P2(1)/c, a = 9.129(3) Å, b = 16.227(5) Å, c = 6.159(2) Å, V = 878.5(5) ų, Z = 2. The palladium atom has a square-planar environment with the trans arrangement of ligands. The complex (C₅H₁₁ON)₂Pd(OAc)₂ (2) has a similar structure, according to spectroscopic data.     

Structure of palladium(I) carbonylcarboxylate clusters [Pd<Subscript>2</Subscript>(CO)<Subscript>2</Subscript>(RCOO)<Subscript>2</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> in solution: NMR and IR study

The structures of palladium carbonylcarboxylate clusters [Pd₂(CO)₂(RCOO)₂] _n (n = 2, R = CH₃, CH₂Cl, CF₃, n = 3, R = CMe₃, CHMe₂, n-C₅H₁₁) are studied in benzene and tetrahydrofuran solutions by IR and ¹H and ¹³C NMR spectroscopy. The clusters in the solid state have a planar cyclic metal framework with pairs of the carbonyl and carboxylate ligands alternately coordinated on its sides. In solutions, compounds under consideration contain one-type carbonyl ligands and one-type carboxylate ligands; their structures are similar to thaso in the solid state.     

Reactions of the biologically active palladium complexes (H<Subscript>2</Subscript>A)<Subscript>2</Subscript>[PdCl<Subscript>4</Subscript>] with glutamic acid as a model of their transformations in blood plasma

Complexation in the systems Pd(II)-Cl⁻-HA-H₂Glu (HA is the l- or d-conformer of 2-methylamino-1-phenylpropanol; H₂Glu is glutamic acid) was studied using pH-metric titration, electronic absorption spectroscopy, and quantum-chemical modeling. It was found that the ratio of the complex species largely depends on pH and the amine, the crucial factor being stabilization of the structures by hydrogen bonding. This provides explanation to the previous data on the different radioprotective activities of the complexes (H₂A)₂[PdCl₄] containing the l- and d-conformers of the ligand HA.     

Cation-anion palladium complexes: the effect of the hydrogen bond character on their stability and biological activity

The results of study of a new class of biologically active palladium complexes (AH _n ) _m [PdCl₄] have been reported. This class of compounds has been discovered by us on the basis of systemic research of composition-structure-biological activity relationships for different classes of platinum metal complexes. It has been shown that the stability of cation-anion palladium complexes and their biological activity are determined by the nature of protonated amines acting as cations and the acid-base properties of the cations-tetrachloropalladate anion systems, manifested in the character and stability of hydrogen bonds that appear in these systems. For the first time, it has been demonstrated in vivo that it is possible to synthesize palladium compounds superior to cisplatin in antitumor activity and not exhibiting immunosuppressive activity, as well as palladium compounds with immunostimulatory and radiomodifying activity. A combination of cytostatics used in oncology or irradiation with palladium complexes leads to significant synergism of their effects and to a considerably higher therapeutic efficiency of such combinations as compared with the treatment effect of each of them alone.     

Palladium nitrosyl carboxylate clusters: Synthesis and reactivity. X-ray structures of Pd4(μ-CO)2(μ-NO)(μ-RCO2)5 (R = Pr, Bu)

New palladium nitrosyl carboxylate complexes Pd₈(CO)_4−m(NO)_m(NO₂)₄(RCO₂)₈ (m = 2, 4) were obtained by the treatment of palladium carbonyl carboxylates clusters cyclo-Pd_n(μ-CO)_n(μ-RCO₂)_n (n = 6) (1) with gaseous nitrogen monoxide. These complexes are the products of CO substitution in early described Pd₈(CO)₄(NO₂)₄(RCO₂)₈ clusters. By adding an excess of corresponding acid to reaction mixture Pd₄(CO)₂(NO)(RCO₂)₅ complexes were obtained, their structures were determined by X-ray diffraction analysis. These clusters are intermediate products of transformation of 6-nuclear initial clusters into various 8-nuclear complexes. This fact demonstrates that carboxylate ligands can be used as stabilizers for intermediate unstable polynuclear palladium compounds.