A 31P NMR STUDY OF TERTIARY PHOSPHINE COMPLEXES OF PLATINUM(II) AND PALLADIUM(II)

Complexes of the type NBu ₄ MCl ₃ PR ₃ R=P.Tolyl,Ph,Bu) (M = Pt, Pd) are prepared by the reaction of MCl ₂ or K ₂ [MCl ₄ ] by phosphine ligands. Addition of NBu ₄ Br or NBu ₄ I to these compounds, in dichloromethane results in a redistribution of halogens and formation of all six isomers of the type MBr _{3 ?X}Cl_XPR ₃ X= 0, 1, 2, and 3 which have been identified by ³¹ P- ¹ H NMR spectroscopy. The intensities show that the products are proportional to the statistical distribution.     

Complexation of Zn(II), Cd(II) and Hg(II) with thiourea and selenourea: A 1H, 13C, 15N, 77Se and 113Cd solution and solid-state NMR study

Zinc(II), cadmium(II) and mercury(II) complexes of thiourea (TU) and selenourea (SeU) of general formula M(TU)₂Cl₂ or M(SeU)₂Cl₂ have been prepared. The complexes were characterized by elemental analysis and NMR (¹H, ¹³C, ¹⁵N, ⁷⁷Se and ¹¹³Cd) spectroscopy. A low-frequency shift of the C=S resonance of thiones in ¹³C NMR and high-frequency shifts of N–H resonances in ¹H and ¹⁵N NMR are consistent with sulfur or selenium coordination to the metal ions. The Se nucleus in Cd(SeU)₂Cl₂ in ⁷⁷Se NMR is deshielded by 87?ppm on coordination, relative to the free ligand. In comparison, the analogous Zn(II) and Hg(II) complexes show deshielding by 33 and 50?ppm, respectively, indicating that the orbital overlap of Se with Cd is better. Principal components of ⁷⁷Se and ¹¹³Cd shielding tensors were determined from solid-state NMR data.     

LIGAND-EXCHANGE REACTION BETWEEN TRIS(1,10-PHENANTHROLINE)METAL(II) AND TRIS(4,7-DIPHENYL-1,10-PHENANTHROLINE)METAL(II) IONS

Abstract

The ligand exchange reaction between [M(phen)₃]²⁺ and [M(DIP)₃]²⁺ (where M is the same and M = Fe^II or Ni^II, phen = 1,10-phenanthroline, DIP = 4,7-diphenyl-1,10-phenanthroline) has been investigated by reversed phase ion-paired chromatography (RP-IPC). The effect of pH and solvent on the ligand-exchange reaction is studied by monitoring the variation in chromatograms with time after mixing. The results have shown that the ligand exchange reaction between [M(phen)₃]²⁺ and [M(DIP)₃]²⁺ takes place in the pH range of 3–8 and the rate of reaction for nickel(II) complexes is about two times slower than that for iron(II) complexes. Experiments on the effect of various solvents on the ligand-exchange reaction have revealed that the rate of reaction is enhanced by the solvent in the following order: (CH₃)₂CO > CHCl₃ ≥ CH₂Cl₂ > CH₃CN > CH₃OH. Elemental analysis and UV-visible spectroscopy confirmed that the products obtained from the ligand-exchange reaction are mixed-ligand complexes containing phen and DIP ligands, i.e., [M(phen)₂(DIP)]²⁺ and [M(phen)(DIP)₂]²⁺.     

Synthesis and structure of highly substituted pyrazole ligands and their complexes with platinum(II) and palladium(II) metal ions

Reaction of 3-methoxycarbonyl-2-methyl- or 3-dimethoxyphosphoryl-2-methyl-substituted 4-oxo-4H-chromones 1 with N-methylhydrazine resulted in the formation of isomeric, highly substituted pyrazoles 4 (major products) and 5 (minor products). Intramolecular transesterification of 4 and 5 under basic conditions led, respectively, to tricyclic derivatives 7 and 8. The structures of pyrazoles 4a (dimethyl 2-methyl-4-oxo-4H-chromen-3-yl-phosphonate) and 4b (methyl 4-oxo-2-methyl-4H-chromene-3-carboxylate) were confirmed by X-ray crystallography. Pyrazoles 4a and 4b were used as ligands (L) in the formation of ML₂Cl₂ complexes with platinum(II) or palladium(II) metal ions (M). Potassium tetrachloroplatinate(II), used as the metal ion reagent, gave both trans-[Pt(4a)₂Cl₂] and cis-[Pt(4a)₂Cl₂], complexes with ligand 4a, and only cis-[Pt(4b)₂Cl₂] isomer with ligand 4b. Palladium complexes were obtained by the reaction of bis(benzonitrile)dichloropalladium(II) with the test ligands. trans-[Pd(4a)₂Cl₂] and trans-[Pd(4b)₂Cl₂] were the exclusive products of these reactions. The structures of all the complexes were confirmed by IR, ¹H NMR and FAB MS spectral analysis, elemental analysis and Kurnakov tests.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.     

Synthesis,characterization, cytotoxicity and computational studies of new phosphine‐ and carbodithioate‐based palladium(II) complexes

In quest of new metallo‐pharmaceuticals with enhanced anticancer activity, four new phosphine‐ and carbodithioate‐based Pd(II) complexes of the type [(R)CS₂Pd(PR₃)Cl] (where R = 4‐(2‐hydroxyethyl)piperazine ( 1 , 2 ), dibenzyl ( 3 , 4 ); PR₃ = diphenyl(p ‐tolyl)phosphine ( 1 , 3 ), tris(4‐tolyl)phosphine ( 2 , 4 )) were synthesized and characterized using elemental analysis, Fourier transform infrared and NMR (¹H, ¹³C and ³¹P) spectroscopies and single‐crystal X‐ray diffraction. The X‐ray diffraction data confirmed the pseudo square‐planar geometry ensuring bidentate coordination mode of carbodithioate ligands. Anticancer activity of the synthesized complexes and their ligands was assessed against human lung (A549), breast (MCF‐7) and prostate (PC3) carcinoma cells using MTT assay. All the tested compounds showed activity in micromolar range. In many cases, the cytotoxicity of the synthesized complexes was higher than or comparable to that of the standard drugs cisplatin and doxorubicin. Complex 3 emerged as the most promising compound with the lowest IC₅₀ values of 4.83, 3.72 and 5.11 μM for A549, MCF‐7 and PC3 carcinoma cell lines, respectively. DNA binding studies were also carried out using UV–visible spectroscopy. We extended our investigations to explore the mechanism of anticancer activity using in silico tools. Based on the mechanism of action of standard drugs used, extensive docking studies were carried out on the three different biomolecular targets.     

1-Methyl-4-ferrocenylmethyl-3,5-diphenylpyrazole: A versatile ligand for palladium(II) and platinum(II)

The syntheses and characterization of two novel ferrocene derivatives containing 3,5-diphenylpyrazole units of general formula [1-R-3,5-Ph₂-(C₃N₂)-CH₂-Fc] {Fc = (η⁵-C₅H₅)Fe(η⁵-C₅H₄) and R = H (2) or Me (3)} together with a study of their reactivity with palladium(II) and platinum(II) salts or complexes under different experimental conditions is described. These studies have allowed us to isolate and characterize trans-[Pd{1-Me-3,5-Ph₂-(C₃N₂)-CH₂-Fc]}₂Cl₂] (4a) and three different types of heterodimetallic complexes: cis-[M{1-Me-3,5-Ph₂-(C₃N₂)-CH₂-Fc]}Cl₂(dmso)] {M = Pd (5a) or Pt (5b)}, the cyclometallated products [M{κ²-C,N-[3-(C₆H₄)-1-Me-5-Ph-(C₃N₂)]-CH₂-Fc}Cl(L)] with L = PPh₃ and M = Pd (6a) or Pt (6b) or L = dmso and M = Pt (8b) and the trans-isomer of [Pt{1-Me-3,5-Ph₂-(C₃N₂)-CH₂-Fc]}Cl₂(dmso)] (7b). In compounds 4a, 5a, 5b and 7b, the ligand behaves as a neutral N-donor group; while in 6a, 6b and 8b it acts as a bidentate [C(sp²,phenyl),N(pyrazole)]⁻ group. A comparative study of the spectroscopic properties of the compounds, based on NMR, IR and UV-Visible experiments, is also reported.     

Zinc(II) and Cadmium(II) Metal Complexes with Bis(tetrazole) Ligands: Synthesis and Crystal Structures

Two new metal complexes [Zn( L¹ )]_n ( 1 ) and [Cd₃( L² )₂Cl₂(H2O)6]_n ( 2 ) (H₂ L¹ = 1,5‐bis(tetrazol‐5‐yl)‐3‐oxapentane, H₂ L² = bis(tetrazol‐5‐yl)methane) have been synthesized and characterized by elemental analysis, IR spectroscopy and single‐crystal X‐ray diffraction analysis. Complex 1 was a 2‐D sheet constructed by L¹ and Zn(II) center, further assembled to form a three‐dimensional (3‐D) supramolecular networks through weak hydrogen‐bonding interactions. In the complex 2 , there were two unequivalent Cd(II) centers, and some of ligands L² adopted chelate coordination mode, and others adopted bridge coordination mode linking the Cd1 center and simultaneously bridging the Cd2 center, the Cl^‐ anions adopted μ₂ bridging mode, ligands L² and the Cl^‐ anions linked the Cd(II) centers to form a 3‐D supramolecular networks.     

Reactions of M2Cl4(PR3)4 (M  Mo and W) with carbon monoxide

The reactions of M₂Cl₄(PR₃)₄ derivatives (M  Mo, W and PR₃  PEt₃, PBu₃ⁿ) with CO at atmospheric pressure in toluene at 70°C to afford M(CO)₃(PR₃)₂Cl₂ and trans-M(CO)₄(PR₃)₂ are reported.     

Synthese und Struktur der Kronenetherkomplexe von Kaliumhexachlorodipalladat(II) und -diplatinat(II)

Synthesis and Structure of Crown Ether Complexes of Potassium Hexachlorodipalladate(II) and -diplatinate(II) K₂[MCl₄] (M ? Pd, Pt) reacts with an excess of crown ether 18-crown-6 in water to give the crown ether complexes of potassium hexachlorodipalladate(II) and -diplatinate(II) [K(18-cr-6)]₂[M₂Cl₆] (M ? Pd, 1 ; M ? Pt, 3 ), respectively, and in methylene chloride to give those of potassium tetrachloropalladate(II) and -platinate(II) [K(18-cr-6)]₂[MCl₄] ( 1 ) (M ? Pd, 2 ; M ? Pt, 4 ), respectively. 1 - 4 are characterized by microanalysis, NMR (¹H, ¹³C), and vibrational spectroscopy. The X-ray structure analyses of the isotypic complexes 1 (P2₁/c; a = 10,9678(8), b = 8,2991(7), c = 22,469(2) Å, β = 98,523(5)°; Z = 2) and 3 (P2₁/c; a = 10,934(3), b = 8.376(3), c = 22,410(5) Å, β = 98,77(3)°; Z = 2) reveal [M₂Cl₆]^2? anions of nearly D_2h symmetry and [K(18-cr-6)]⁺ cations, in which the distance of K⁺ to the mean plane of the crown ether defined by its six oxygen atoms amounts to 0,830(4) Å in 1 and 0,821(2) Å in 3 , respectively. There are tight contacts between cations and anions (d(K-Cl): 3,341(2)/3,260(2) Å ( 1 ); 3,348(4)/3,259(4) Å ( 3 )).     

Rhodium(III), palladium(II) and platinum(II) complexes of Bis(o-aminobenzenesulfonyl)ethylenediamine

New complexes of the formulae K₃[RhL ₃]·2 H₂O, [PdL]·H₂O and [M(LH₂)Cl₂] [whereM = Pd, Pt andLH₂ = bis(o-aminobenzenesulfonyl)ethylenediamine] have been prepared and characterized by conductivity measurements, thermogravimetric analysis, X-ray powder patterns and IR, Ligand Field and¹H-NMR spectroscopy.

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Rhodium(III), Palladium(II)- und Platin(II)-Komplexe mit Bis(o-aminobenzolosulfonyl)ethylendiamin (Kurze Mitteilung)

Zusammenfassung Neue Komplexe der allgemeinen Formeln K₃[RhL ₃]·2H₂O, [PdL]·H₂O und [M(LH₂)Cl₂] mitM = Pd, Pt undLH₂ = Bis(o-aminobenzolosulfonyl)ethylendiamin wurden dargestellt und mit Konduktionsmessungen, thermogravimetrischen Analysen, Röntgenstrukturanalysen, IR, Ligandfeld- und¹H-NMR-Spektroskopie charakterisiert.

     

SYNTHESIS AND CHARACTERIZATION OF TRIS(ALKYLISOCYANIDE) BIS(TRIARYL-PHOSPHINE)COBALT(II) COMPLEXES

Abstract

A series of complexes having the general formula, [Co(CNR)₃(PR₃)₂]X₂, X = ClO₄, BF₄ with CNR = CNCMe₃, CNCHMe₂, CNC₆H₁₁. CNCH₂Ph and PR₃ = PPh₃, P(C₆H₄Me-p)₃, P(C₆H₄OMe-p)₃ has been synthesized and characterized. Synthesis can be achieved by reaction of [Co(CNR)₄(AsPh₃)₂]X₂ complexes with controlled excess of PR₃ ligands, and by AgClO₄/AgBF₄ oxidation of the [Co(CNR)₃(PR₃)₂]X complexes. The latter procedure is preferable. Alternate syntheses of the [Co(CNR)₃(PR₃)₂]X complexes have also been employed. Five-coordinate Co(II) complexes have not been obtained using CNCMe₃ with P(C₆H₄Me-p)₃ ligands, CNCH₂Ph with P(C₆H₄OMe-p)₃ ligands, or CNC₄H_9-n with PPh₃ ligands. [Co(CNC-Me₃)₃{P(C₆H₄Cl-p)₃}₂]ClO₄ produced only [Co{CNCMe₃)₄H₂O](ClO₄)₂ upon forced oxidation with excess AgClO₄. [Co(CNR)₃(PR₃)₂]X₂ complexes appear to undergo varying degrees of distortion from regular (i.e., D _3h symmetry) axially-disubstituted trigonal bipyramidal coordination in the solid state, as evidenced by v(-N°C) IR patterns, but to assume regular trigonal bipyramidal coordination in solution. Effective magnetic moments indicate one-electron paramagnetism, and solution electronic spectra are compatible with trigonal bipyramidal coordination.     

Kinetic Study of the Reduction of Bromate Ion by Tris(1,10-Phenanthroline)Iron(II) and Aquoiron(II) Ions — Implication for the Bromate-Gallic Acid Oscillating Reaction

The kinetics of the bromate oxidation of tris(1,10-phenanthroline)iron(II) (Fe(phen)₃²⁺) and aquoiron(II) (Fe²⁺ (aq)) have been studied in aqueous sulfuric acid solutions at μ = 1.0M and with Fe(II) complexes in great excess. The rate laws for both reactions generally can be described as -d [Fe(II)]/6dt = d[Br^?]/dt = k[Fe(II)] [BrO^?₃] for [H⁺]₀ = 0.428–1.00M. For [BrO^?₃]₀ = 1.00 × 10^?4M. [Fe²⁺]₀ = (0.724–1.45)x 10^?2 M, and [H⁺]₀ = 1.00M, k = 3.34 ± 0.37 M^?1s^?1 at 25°. For [BrO^?₃]₀ = (1.00–1.50) × 10^?4M, [Fe²⁺]₀ = 7.24 × 10^?3M ([phen]₀ = 0.0353M), and [H⁺]₀ = 1.00M, k = (4.40 ± 0.16) × 10^?2 M^?1s^?1 at 25°. Kinetic results suggest that the BrO^?₃-Fe²⁺ reaction proceeds by an inner-sphere mechanism while the BrO^?₃-Fe(phen)₃²⁺ reaction by a dissociative mechanism. The implication of these results for the bromate-gallic acid and other bromate oscillators is also presented.     

Zn(II), Cd(II) and Hg(II) complexes with 1-(p-methoxybenzyl)-2-(p-methoxyphenyl)benzimidazole: Syntheses, structures and luminescence

Five coordination compounds Zn(mbmpbi)₂Cl₂ (1), Zn(mbmpbi)₂Br₂ (2), Cd(mbmpbi)₂Cl₂ (3), Hg(mbmpbi)₂Cl₂ (4) and Hg(mbmpbi)₂Br₂ (5) were synthesized by the reaction of 1-(p-methoxybenzyl)-2-(p-methoxyphenyl)benzimidazole (mbmpbi) with the corresponding metal halides. The complexes have been characterized by elemental analysis, conductance measurements, FT-IR, ¹H NMR and photoluminescence spectral studies. The ligand mbmpbi exhibits the N-benzimidazole coordination. The structures of 3-5 have been determined by single crystal X-ray diffraction. These three complexes are isostructural, crystallizing in the monoclinic system, P2/n space group with a distorted tetrahedral geometry around the metal ion. Zn(II) and Cd(II) complexes show strong blue emission in solid state at room temperature.     

Palladium and Platinum Complexes from Methyl(2-Thienyl) Chalcogenides and BIS(2-Thienyl) Dichalcogenides

The preparation of [M(C₄H₃SECH₃)₂Cl₂] (M = Pd, Pt; E = Se, Te) and [Pd₆Te₆(C₄H₃S)₂(PPh₃)₆Cl₂] from methyl(2-thienyl)chalcogenides and bis(2-thienyl) ditelluride is reported. The products are identified and characterized by X-ray crystallography and by ⁷⁷Se and ¹²⁵Te NMR spectroscopy.     

Synthesis and crystal structure characterization of iron(II), cobalt(II) and nickel(II) complexes with 1,3-bis(2-pyridylmethylthio)propane

Three new mononuclear complexes of nitrogen–sulfur donor sets, formulated as [Fe^II(L)Cl₂] (1), [Co^II(L)Cl₂] (2) and [Ni^II(L)Cl₂] (3) where L = 1,3-bis(2-pyridylmethylthio)propane, were synthesized and isolated in their pure form. All the complexes were characterized by physicochemical and spectroscopic methods. The solid state structures of complexes 1 and 3 have been established by single crystal X-ray crystallography. The structural analysis evidences isomorphous crystals with the metal ion in a distorted octahedral geometry that comprises NSSN ligand donors with trans located pyridine rings and chlorides in cis positions. In dimethylformamide solution, the complexes were found to exhibit Fe^II/Fe^III, Co^II/Co^III and Ni^II/Ni^III quasi-reversible redox couples in cyclic voltammograms with E_1/2 values (versus Ag/AgCl at 298 K) of +0.295, +0.795 and +0.745 V for 1, 2 and 3, respectively.     

A study on synthesis and thermal,spectral and biological properties of carboxylato-Mg(II) and carboxylato-Cu(II) complexes with bioactive ligands

Summary Synthesis, elemental (CHN), spectral (FTIR), thermogravimetry (TG), differential thermal analysis (DTA) and complexometric titration have been applied to the investigation of the thermal behavior and structure of the complexes: Mg(ac)₂(mpc)₃·3H₂O(I), Mg(Clac)₂(mpc)₂·3H₂O(II), Mg(Cl₂ac)₂(mpc)₂·3H₂O(III), Mg(Cl₃ac)₂(mpc)₂·3H₂O(IV) and [Cu(ac)₂(mpc)]₂·3H₂O(V) (ac=CH₃COO^-, Clac=ClCH₂COO^-, Cl₂ac=Cl₂CHCOO^-, Cl₃ac=Cl₃CCOO^- and mpc=methyl-3-pyridyl carbamate). Thermal decomposition of these complexes is a multi-stage processes. The composition of the complexes and the solid state intermediate and resultant products of thermolysis had been identified by means of elemental analysis and complexometric titration. The possible scheme of decomposition of the complexes is suggested. Heating the complexes first resulted in a release of water molecules. The TG results show that the loss of the volatile ligand (mpc) occurs in one step for complexes II, IV and V, and in two steps for complexes I and III. The final solid product of thermal decomposition was MgO or CuO. The thermal stability of the complexes can be ordered in the sequence: I=II<IV<III<V. Mpc was coordinated to Mg(II) or Cu(II) through the nitrogen atom of its heterocyclic ring. IR data suggest to a unidentate coordination of carboxylates to magnesium or copper n complexes I-V. The preliminary studies have shown that the complexes do have antimicrobial activities against bacteria, yeasts and/or fungi. The highest antimicrobial activities were manifested by the complex V.     

Syntheses,structures, and fluorescent properties of three Zn(II) and Cu(II) complexes of different ligands derived from 3,6-bis(2-pyridyl)-1,2-dihydro-1,2,4,5-tetrazine

Three supramolecular complexes [Zn(HL₁ )₂(H₂O)₂(ZnCl₄)₂] (1), [Cu(L₂ )₂Cl₂] (2), and [Zn(L₃ )Cl₂] (3) have been synthesized and characterized by single crystal X-ray diffraction analysis (L₁ = 3,5-di(2-pyridyl)-4-amino-1,2,4-triazole, L₂ = 3,5-di(2-pyridyl)-1,2,4-triazole, and L₃ = 2-pyridinecarboxylic acid (pyridin-2-ylmethylene)-hydrazide). In 1, anion–π interactions between Cl^? and the π-systems of L₁ are observed and anion–π, hydrogen bonding and π–π stacking interactions link the two complex units of [Zn(HL₁ )₂(H₂O)₂]⁴⁺ and [ZnCl₄]^2? to form a 3-D supramolecular network. In 2, π–π stacking interactions between aromatic rings of 1,2,4-triazole and pyridine rings are observed; in 3, hydrogen bonding of Cl ··· H–N and π–π stacking interactions between parallel pyridine rings of L ₃ are observed. The mechanisms of rearrangement reactions of L to L₁ –L₃ are discussed. The fluorescent properties for solid 1 and 3 are also investigated.     

Synthesis and Characterization of Novel Trans-Mixed Diamine Platinum(II) and Platinum(IV) Complexes

A series of novel trans-mixed diamine platinum(II) and platinum(IV) complexes of type trans-[Pt^II(R-NH₂)(R'-NH₂)Cl₂] and trans -[Pt^IV(R-NH₂)(R'-NH₂)Cl₄] (where R-NH₂ = ethylamine or butylamine and R'-NH₂ = methylamine, propylamine, isopropylamine, pentylamine, or hexylamine) was synthesized and characterized using elemental analysis and infrared and ¹⁹⁵Pt nuclear magnetic resonance spectroscopic techniques.     

Crystal structure of bis(l-arginine)copper(II) hexachlorodimercurate, [Cu(l-Arg)2]Hg2Cl6

By means of X-ray diffraction the chain structure of [Cu(l-Arg)₂]Hg₂Cl₆ (monoclinic, a = 10.2348(9) Å, b = 9.1386(7) Å, c = 14.8521(14) Å, β = 97.455(11)°, space group P2₁) is established. The chains are formed by square-planar [Cu(l-Arg)₂]²⁺ cations of the type trans-[Cu(N)₂(O)₂] (l-Arg is the zwitter-ion of arginine; Cu-N 1.992 Å and 1.938(6) Å, Cu-O 1.953 Å and 1.967(4) Å) that are bonded to two adjacent binuclear [Cl₂Hg(μ-Cl)₂HgCl₂]^2? ions through its clorine atoms Cl (Hg-Cl bonds are within 2.34–2.78 Å). With these two additional Cu…Cl contacts Cu adopts the geometry of an elongated octahedron with two apical Cl (Cu-Cl 2.961 Å and 3.064(3) Å).