Synthesis and spectral studies on platinum complexes with mono- and bidentate N-donor organic ligands

Platinum(II) complexes of types PtLX₂, PtL₂X₂, PtLX″ and the Pt(IV) complexes PtLXY (where L = mono- or bidentate organic ligand containing nitrogen donor atoms; X = Cl or Br; X′ = oxalate or malonate and Y = Br) have been synthesized and characterized from their elemental analysis, IR and X-ray photoelectron spectral data. The Pt 4f_7/2 binding energies indicate that 1,8-naphthalene-diamine ligand is a better donor of electron density to the metal than other ligands studied here. The Cl 2p_3/2 binding energies in the square planar Pt(II) complexes are observed in the range 198.8 ± 0.8 eV. The ν (PtCl) vibrations (ca 335 and 320 cm^?1) corresponding to two cis-Cl ligands were observed in the IR spectra.The extent of the interaction between cis-dichloro-bis-(theophylline)platinum(II) with calf thymus DNA has beenstudied. The UV difference spectra resulting from aquated Pt^II(theoph)₂-DNA interaction exhibit bands at 282 and 292 nm attributable to the change in the electron distribution of the base moieties induced by binding with platinum and due to the loss of base stacking. Melting profiles for the DNA samples treated with Pt-complex showed decrease in the melting temperature. Binding of the guanine residues of the DNA, involving probably (N7)-0(6) positions to the metal is implied.     

Perhalophenyl complexes of palladium(II) containing keto-stabilized phosphorus ylides of the type Ph2P(CH2)nPPh2CHC(O)R

From suitable perhalophenyl derivatives of palladium(II), viz.: Pd(C₆F₅)₂-(SC₄H₈)₂, [Pd(μ-X′) (C₆X₅)₂]₂(NBu₄)₂, [Pd(μ-Cl)(C₆X₅)(SC₄H₈)]₂ (X = F, Cl, X′ = Cl, Br), new complexes of various types have been prepared, viz.: trans-Pd(C₆F₅)₂(Y)₂, Pd(C₆X₅)₂(Y), PdCl(C₆X₅)(Y) (X = F, Cl). The neutral ligand Y is a keto-stabilized phosphorus ylide of the type Ph₂P(CH₂)_nPPh₂CHC(O)R (n = 1, R = CH₃, C₆H₅; n = 2, R = C₆H₅) acting in a terminal monodentate P-donor or a bidentate chelate P,C-donor mode. The reaction of PdCl(C₆F₅)(Y) complexes with HCl leads to the corresponding PdCl₂(C₆F₅)(YH) complexes in which the phosphonium cation [YH]⁺ behaves as monodentate P-donor at its phosphinic end.IR and ³¹P NMR spectroscopy were used to decide the coordination mode of the ligands and, in some cases, to reveal the presence of two isomers.     

Palladium complexes based on optically active terpene derivatives of ethylenediamine

Novel chiral palladium diamino complexes with the asymmetric donor N atom Pd(En*)X₂ (where En* = N,N′-bis{[(1S,5R)-6,6-dimethylbicyclo[3.1.1]hept-2-en-2-yl]methyl}-1,2-ethylenediamine; X = Cl and Br) were obtained and characterized. Nitrogen-containing derivatives of the natural monoterpene a-pinene were studied as accessible optically active ligands.     

NMR (195Pt and 13C) contribution to the study of some Pt(II), Pt(IV) and mixed-valence thioamido complexes

The ¹⁹⁵Pt and ¹³C chemical shifts (δ_Pt and δ_c) are reported for platinum(II), platinum(IV) and class II mixed-valence complexes, with general formula [PtL₄]X₂, cis- and trans-PtL₂X₂, PtL₂X₄ and Pt₂L₄X₆ (where L may be thiourea, 2-imidazolidine-thione, tetrahydro 2-pyrimidinethione, thiocaprolactam, pyridine-2-thione and tetramethylthiourea, and X may be Cl or Br). The ¹⁹⁵Pt chemical shifts can be understood in view of ¹³C data in terms of variations of electronegativities and σ-donor abilities of ligands attached to platinum.     

Mononuclear and binuclear lanthanum(III) complexes of macrocyclic ligands derived from 2,6-diacetylpyridine

Two novel series of complexes of types [La(DAPCH)X₂]X and [La(DAPTC)X₂]X (DAPCH = a potentially pentadentate ligand derived from 2,6-diacetylpyridine and carbohydrazide; DAPTC = a potentially tridentate ligand derived from 2,6-diacetylpyridine and thiocarbohydrazide; X = Cl, Br or NO₃) have been synthesized and characterized by elemental analyses, conductance measurements and IR spectral data. All these complexes contain terminal hydrazinic nitrogen atoms with an unshared electron pair and may take part in nucleophilic condensations. Therefore, the reactions of these complexes with 2,6-diacetylpyridine have also been studied which cause ring closure and formation of macrocyclic ligand complexes. Two types of cyclic products, viz. mononuclear [La(mac)X₂]X, [La(mac′)X₂]X and binuclear [La₂(mac)X₄]X₂, [La₂(mac′)X₄]X₂ (mac- = macrocyclic ligand derived from DAPCH and 2,6-diacetylpyridine; mac′ = macrocyclic ligand derived from DAPTC and 2,6-diacetylpyridine; X = Cl, Br or NO₃) have been isolated by carrying out the reactions by different methods. The IR spectra of these cyclic products are reported.     

EPR detection of [Cu(mnt)X2]2−—A possible halogenide stabilized intermediate in ligand exchange reactions

During the reaction of [Cu(mnt)₂]^2? with CuX₂ (X = Cl, Br) [Cu(mnt)X₂]^2? species are formed and characterized EPR spectroscopically supporting a dissociative mechanism for ligand exchange reactions between [Cu(mnt)₂]^2? and other Cu(II), Ni(II) and Pd(II) complexes which contain unsaturated dichalcogeno ligands.     

Palladium(II) and platinum(II) complexes of rhodanine and 3-methylrhodanine

Summary The following palladium(II) and platinum(ll) complexes of rhodanine (HRd) and 3-methylrhodanine (MRd) have been prepared: Pd(HRd)_1.5Cl₂, Pd(HRd)₂Br₂, Pd(HRd)₂Br₂ · 0.25 EtOH, M(MRd)₂X₂ [M = Pd, X = Cl (0.25 EtOH) or Br; M = Pt, X = Cl or Br], Pd(MRd)₃Br₂, and M(MRd)₄(ClO₄)₂ (M = Pd or Pt). The ligands are coordinated to the metal through the thiocarbonylic sulphur atom. Pd(HRd)_1.5Cl₂ has presumably a structure such as (X = Cl or Br) complexes have a trans-planar coordination. Pd(MRd)₂X₂ (X = Cl or Br) complexes arecis-planar coordinated. Pd(MRd)₃Br₂ has presumably a square coordination with two MRd molecules and two CI ionscis-coordinated in the equatorial plane, and a MRd molecule and a Cl ion weakly bonded in apical position. The M(MRd)₄(ClO₄)₂ complexes have square planar coordination.Author to whom all correspondence should be addressed.     

Metal complexes of sulphur and nitrogen-containing ligands: Complexes of s-benzyldithiocarbazate and a schiff base formed by its condensation with pyridine-2-carboxaldehyde

Tris- and bis-ligand complexes of nickel(II) with S-benzyldithiocarbazate (SBDTC) having the general formulae Ni(SBDTC)₃X₂·H₂O (X = Cl, Br and NO₃) and Ni(SBDTC)₂X₂ (X = Cl and NCS), respectively, were synthesized and characterized by electronic and IR spectroscopy and magnetic measurements. The ligand acts as a bidentate sulphur-nitrogen chelating agent. Both the tris- and bis-ligand cationic nickel(II) complexes are high-spin with magnetic moments of ca. 3.10 B.M. On the basis of magnetic and spectral evidence octahedral structures are assigned to these complexes.Under alkaline conditions complexes of the deprotonated ligand having the formulae M(SBDTCA)₂[M = Ni(II) and Zn(II); SBDTCA = anion of SBDTC] were isolated. The nickel(II) complex is square-planar.The Schiff base

CH=N-NHCSS₂C₆H₅(NNSH)forms intensely coloured crystalline complexes with nickel(II) and copper(II) having the general formula M(NNS)X [M = Ni(II) and Cu(II); X = Cl, Br or NO₃ and NNS is the anion of NNSH]. The nickel(II) complexes are diamagnetic. The magnetic behaviour of the Cu(NNS)X (X = Cl and Br) complexes over the temperature range 320-93°K obeys the Curie-Weiss law. The variable-temperature magnetic data coupled with IR and electronic spectral evidence support square-planar stereochemistries for the copper(II) complexes.     

Synthesis and characterization of 1-Methyl-4-mercaptopiperidine complexes of nickel(II), palladium(II) and platinum(II)

Summary Complexes of formulae Ni(HRS)₂X₂ (X=Cl or Br), M(HRS)₂Y₂ (M=Ni or Pd; Y=NO₂ or C1O₄), Pd(HRS)X₂ (X=Cl, Br or I), Pt(HRS)X₂ (X=Cl or Br), Pt(HRS)₂(ClO₄)₂ and M(RS)₂ (M=Pd or Pt) where HRS and RS denote 1-methyl-4-mercaptopiperidine in the zwitterionic or in the thiolato form, respectively, have been prepared and characterized. In all the complexes the ligands are coordinated exclusively through sulphur. Polymeric structures consisting of square-planar geometry with sulphur-bridged metal atoms are proposed in each case.     

Application of spectroscopic techniques to the complexes formed by reaction of zeise's salt derivatives with carbon monoxide

IR, ¹H NMR and electronic spectra are reported for the complexes trans-[PtX₂(CO)(L)] (X = Cl or Br; L = NH₃, pyridine, pyridine-N-oxide, aniline or imidazole) and trans-[Pt₂X₄(CO)₂(pyrazine)] (X = Cl or Br). Assignments for the internal ligand modes and metal-ligand vibrations are deduced from the band shifts caused by deuteration of the ligands (L). The simplicity of the IR spectra, particularly in the v(CO) region, is consistent with a trans-configuration. The ¹H NMR data show ¹⁹⁵Pt-H coupling at ambient temperature, suggesting a slow exchange, unlike the corresponding ethylene complexes which are highly fluxional at ambient temperatures. Assignments are provided for the UV spectra and the previously reported red shift is observed in the 5d(Pt) →π* transition which results from the replacement of Cl by Br in the complexes.     

Cu(I) complex compounds with isonicotinic acid and ethyl isonicotinate

Isonicotinic acid (HINA) forms only 1:1 complexes with the 3 cuprous halides, while ethyl isonicotinate (EtIN) forms complexes of the general formula EtIN_n ·CuX, where n = 1, 1·5, 2, 3 and 4 and X is Cl, Br, I, CN, SCN and ClO₄. These complexes have been prepared by reduction of Cu(II) salts by ascorbic acid in presence of the ligand. The complexes are characterized by their analytical data, diamagnetism and conductivity measurements. Their reflectance spectra showed intense absorption in the visible region which is undoubtedly due to M → L charge transfer. Their IR spectra are discussed.     

Thermal and Some other Properties of 2,4′-Bipyridyl Complexes with Various Salts of Lead(II)

New complexes of lead(II) with 2,4′-bipyridyl (L), with the general formulae PbL₂X₂ (where X ^?1=Cl, Br, I, NCS) and PbL₃X₂ (where (X]^?1=NO₃, ClO₄), have been prepared. Analysis of the IR spectra indicates that the 2,4′-bipyridyl is bonded to the Pb(II) ion through the least hindering N(4′). The thermal decompositions of the complexes were studied under non-isothermal conditions in air. The intermediates of decomposition at different temperatures were characterized by thermal analysis (TG and DTG), chemical analysis and X-ray diffraction. Upon heating, the complexes undergo full or partial deamination. The complexes PbL₂Cl₂ and PbL₂Br₂ decompose to volatile lead(II) halide. PbO is the final product of decomposition for the other complexes.     

Synthesis,spectroscopic and the biological activity studies of thiosemicarbazones containing ferrocene and their copper(II) complexes

Two Schiff bases, 1-acetylferrocene thiosemicarbazone (HL¹) and 1,1′-diacetyl-ferrocene dithiosemicarbazone (H₂L²) and their copper(II) complexes were prepared and characterized by elemental analysis, magnetic susceptibility, conductivity, and spectral (IR, UV–Vis, ESR) measurements The IR spectra showed that HL¹ acts as neutral or monobasic bidentate ligand, coordinating to copper(II) through either thiono- or thiolo-sulphur and azomethine-N atoms, whereas H₂L² is a neutral or dibasic mononucleating or binucleating quadridentate ligand coordinating through the same atoms. Other spectral measurements indicate that complexes [(L¹)₂Cu], [(L²)Cu] and [(HL¹)₂Cu]X₂, X?=?Cl, Br or ClO₄ have square-planar geometry around copper(II) while [(HL¹)CuX₂] and [(H₂L²)Cu₂X₄], X?=?Cl or Br, have distorted tetrahedral geometry. The biological activity studies of the complexes and the free ligands towards two gram positive and two gram negative bacteria and one fungal species have been studied and the potential is related to the nature and structure of the tested compounds.     

Substitution reactions of trans-[PdXPh(SbPh3)2J (X=Cl or Br) with nitrogen,phosphines and arsenic donor ligands. Crystal structures of trans-[PdClPh(PPh3)2], [PdClPh(bipy)], [PdClPh(dppm)]2, and [PdBrPh(dppm)]2

Exchange reactions of trans-[PdXPh(SbPh₃)₂] (1) (X=Cl or Br) with ligands L in refluxing dichloromethane give the palladium phenyl complexes [PdXPhL₂] (X=Cl, L=PPh₃, AsPh₃, L₂=2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (dmbipy), 1,10-phenanthroline (phen); X=Br, L=PPh₃, L₂=bipy). Treatment of the complexes with bis(diphenylphosphino)methane (dppm) in refluxing dichloromethane gives [PdXPh(dppm]₂. These complexes have been characterised by microanalysis, IR and ¹H NMR spectroscopic data together with single crystal X-ray determinations of the phenyl palladium complexes, trans-[PdClPh(PPh₃)₂], [PdClPh(bipy)], [PdClPh(dppm)]₂, and [PdBrPh(dppm)]₂.     

Synthesis and reactivity of new methylallylpalladium(II) complexes with bidentate 2-(methylthio-N-benzylidene)anilines

This work describes the synthesis, characterisation and reactivity of new methylallyl Pd(II) complexes that contain bidentate 2-(methylthio-N-benzylidene)anilines as ligands. The reaction of the binuclear complex [(η³-Me-allyl)Pd(μ-Cl)₂] with AgBF₄ causes the total abstraction of the chloride bridges, with the subsequent formation of an intermediary fragment of Pd(II). This fragment in turn reacts with neutral bidentate 2-(methylthio-N-benzylidene)anilines to give cationic complexes of Pd(II) of general formula [(η³-Me-allyl)Pd(η²-S,N-MeSC₆H₄NCHC₆H₄(X)Y)]BF₄ [X=H, Y=H (1); X=F, Y=H (2); X=Me, Y=H (3); X=H, Y=Cl (4); X=H, Y=Me₂N (5); X=H, Y=NO₂ (6)]. The new complexes were characterised by means of elemental analysis, IR, NMR [¹H, ¹⁹F{¹H}, ¹³C{¹H}, ³¹P{¹H}, Dept, ¹H-¹H-COSY, HSQC, HMBC] and mass spectroscopies. The reaction of the Pd(II) complexes with nucleophiles such as NaI, (EtO)₂PS₂K, KCN, KSCN or NaH lead to the deco-ordination of the bidentate ligands to give dimeric or polymeric complexes of Pd(II). The reactivity pattern observed is discussed by a theoretical analysis based on Fukui functions.     

Mössbauer characterization of some new high-spin iron complexes with urea and thiourea derivatives

New high-spin iron(II) and iron(III) complexes with urea, thiourea and related ligands have been prepared and characterized by electronic, infrared, magnetic and Mössbauer measurements. The complexes with general formula FeL_nX₂ (n = 4, 6; X = Cl, Br, I), FeL₂(SCN)₂ and FeL_nX₃ (n = 2, 3, 6; X = Cl, Br) have octahedral geometry and some of them are polymeric, while the FeL₂X₂ complexes (X = Cl, Br) present monomeric tetrahedral geometry. Some results of temperature dependence of the Mössbauer parameters are presented and related to the estimated crystal field values.     

Zinc (II), cadmium (II) and mercury (II) complexes of 2-methyl-benzothiazole

The following zinc (II), cadmium (II) and mercury (II) complexes of 2-methyl-benzothiazole (2Mebt=L) have been prepared and studied by conductometric methods, i.r. and Raman spectra: ML₂ (M = Zn, X = Cl, I, NO₃; M = Cd, X = NO₃, ClO₄; M = Hg, X = NO₃), ML_1.5X₂ (M = Zn, X = ClO₄ (H₂O); M = Hg, X = ClO₄) and MLX₂ (M = Cd and Hg, X = Cl, Br, I). The ligand is N-bonded when acting as monodentate and N,S-bonded as bridging ligand. The halide, nitrate and perchlorate ions are coordinated.     

Stereochemical versatility of Cu(II): Cu(II) complexes of benzyl methyl ketone semicarbazone

Copper(II) complexes of the general composition Cu(ligand)₂X₂ (where X = Cl, Br, NO₃, ClO₄, and $\text{1}\text{2}$SO₄) and Cu(ligand)(CH₃COO)₂ have been synthesised with benzymethylketonesemicarbazone. All the complexes prepared have been characterised by elemental analysis, magnetic moment, conductance, IR, electronic and electron spin resonance spectral studies. The complexes Cu(ligand)₂X₂ (X = Cl, Br, NO₃) and Cu(ligand)(CH₃COO)₂ may have tetragonal symmetry while the Cu(ligand)₂X₂ (ClO₄ and $\text{1}\text{2}$SO₄) may be five-coordinate trigonal bipyramidal in structure.     

Complexes of N-methyl-4-mercaptopiperidine with some metal ions

Complexes of N-methyl-4-mercaptopiperidine in its zwitterionic form with Co(II) and Zn(II) salts, and in anionic form with Cu(I) and Ag(I) salts have been prepared. Stoichiometry of the complexes, Co(HRS)₂COX₄ (X = Cl and Br), Co(HRS)₂X₂ (X = ClO₄, NO₃), Co(HRS)₃X₃ (X = NO₃, ClO₄), Zn(HRS)₂ZnX₄ (X = Cl and Br), Zn(HRS)₂(NO₃)₂, Ag(RS) and Cu(RS), have been established by chemical analysis. The solid complexes have been further characterized by IR and electronic spectra measurements.     

Preparation,infrared, Raman and N.M.R. spectra of N,N′-Diethylthiourea complexes with zinc(II), cadmium(II) and mercury(II) halides

Several complexes of N,N′-diethylthiourea (Dietu) with zinc(II), cadmium(II) and mercury(II) halides were prepared and characterized by i.r. (4000–60 cm^?1), raman (400–60 cm^?1), in the solid state and n.m.r. and conductometric methods in solution. The complexes Zn(Dietu)₂X₂, Cd(Dietu)₂X₂ (X ? Cl, Br, I) and Hg(Dietu)₂X₂ (X ? Br, I) are tetrahedral species in which intramolecular ? NH …? X interactions have been observed. The 1:1 mercury(II) complexes, Hg(Dietu)X₂ (X ? Cl, Br), appear to have a dimeric tetrahedral halide-bridged structure in the solid state. In all these complexes N,N′-diethylthiourea is sulphur-bonded to the metal.