Some mixed-ligand palladium(II) complexes and comparison of their photosensitizing ability with analogous platinum(II) complexes

Three new palladium(II) complexes of formula [Pd(bipy)(XX)] [where bipy is 2,2′-bipyridine and XX are dianions of catechol (CAT), 4-tert-butylcatechol (BCAT) and 3,4-dimercaptotoluene (DMT)] have been prepared and characterized by physical methods. A ligand-ligand charge-transfer band in each complex was observed between 16–21 kK (ε_max = 1500–2200 1 mol^?1 cm^?1) which is negatively solvochromic. These palladium(II) complexes in dimethylformamide photosensitize the formation of singlet oxygen and their ability to photosensitize triplet oxygen (³O₂) to singlet oxygen (¹O₂) are compared with analogous platinum(II) complexes. In addition, 2,2′-bipyridine-platinum(II) complex of 3,4-dimercaptotoluene also undergoes self-sensitized photooxidation.     

Fluorinated barrelene-ruthenium(II) complexes with anionic chelating ligands

Reaction of ruthenium(III) chloride with the barrelene diolefins (tetrafluoro-benzobarrelene (TFB) or (trimethyltetrafluorobenzobarrelene) (Me₃ TFB) leads to the formation of the polymeric complexes [RuCl₂(barrelene)]_n. These compounds react with anionic chelating ligands with formation of new hexacoordinated neutral complexes of the general formulae [Rh(chelate)₂(barrelene)], where chelate = acetylacetonate, tropolonate, salicylal-dehydate and 8-oxyquinolinate. The IR and ¹H NMR spectra of the complexes are given and discussed.     

Palladium(II) malonato complexes with some heterocyclic ligands

Palladium(II) malonato complexes with heterocyclic ligands have been synthesized and characterized by spectroscopic and biological studies. The compoun     

Alkyl,hydrido and related compounds of ruthenium with trimethylphosphine and bis(1,2-dimethylphosphino)ethane. X-ray crystal structures of cis-hydridoethyltetrakis(trimethylphosphine)-ruthenium(II) and ethylene tetrakis-(trimethylphosphine)ruthenium(0)

The interaction of trans-RuCl₂(PMe₃)₄ with R₂Mg, depending on the reaction conditions and the alkyl groups gives either (C₂H₄)Ru(PMe₃)₄ or cis-Ru(H)(C₂H₅)(PMe₃)₄ for R = ethyl, and cis-Ru(H)(ⁿC₃H₇(PMe₃)₄ for R = n-propyl. The interaction of Et₂Mg with trans-RuX₂(dmpe)₂ (X = Cl, CO₂Me) gives either cis-Ru(Et₂)dmpe)₂ for X = Cl or trans-Ru(Et)₂(dmpe)₂ for X = CO₂Me. NMR data for (C₂H₄)Ru(PMe₃)₄ suggest that ethylene is bound in the η² or metallocyclopropane form, which is confirmed by a single-crystal X-ray diffraction study. This shows a relatively long carbon-carbon bond distance of 1.44(1)Å between the “ethylene” carbons. The structure of cis-Ru(H)(C₂H₅)(PMe₃)₄ has also been confirmed by a single-crystal X-ray diffraction study. Possible mechanisms for the observed reactivities are considered.     

New biimidazole and bibenzimidazole derivatives: mono and binuclear palladium(II) or platinum(II) complexes and heterobinuclear palladium(II)-rhodium(I) or platinum(II)-rhodium(I) complexes

Novel neutral biimidazolate or bibenzimidazolate palladium(II) and platinum(II) complexes of the type M(NN)₂(dpe) [M = Pd, Pt; (NN)₂^2? = BiIm^2?, BiBzIm^2?. dpe = 1,2-bis(diphenylphosphino) ethane] have been obtained by reacting MCl₂(dpe) with TI₂(NN)₂. Complexes M(NN)₂(dpe) which are Lewis bases react with HClO₄ or [M(dpe)(Me₂CO)₂](ClO₄)₂ to yield, respectively, mononuclear cationic complexes of general formula [M{H₂(NN)₂](dpe) (M = Pd, Pt; H₂(NN)₂ = H₂BiIm, H₂BiBzIm) and homobinuclear palladium(II) or platinum(II) cationic complexes of the type [M₂{μ - (NN)₂}(dpe)₂](ClO₄)₂. Reactions of M(BiBzIm)(dpe) with [Rh(COD) (Me₂CO)_X](ClO₄) render similar heterobinuclear palladium(II)-rhodium(I) and platinum(II)-rhodium(I) cationic complexes, of general formula [(dpe)M(μ-BiBzIm)Rh(COD)](ClO₄) (M = Pd, Pt; COD = 1,5-cyclooctadiene). Di- and mono-carbonyl derivatives [(dpe)M(μ-BiBzIm)Rh(CO)L](ClO₄) (M = Pd, Pt; L = CO, PPh₃) have also been prepared. The structures of the resulting complexes have been elucidated by conductance studies and IR spectroscopy.     

Spectroscopic and biological studies on palladium(II) complexes with N-ethyl and N-propylimidazole

Palladium(II) halide complexes with N-ethylimidazole (N-EtIm) and N- propylimidazole (N-PropIm) with general formulae Pd(L)₂X₂ and Pd(L)₄X₂ (X = Cl, Br, I) were prepared and characterized by spectroscopic methods and conductivity measurements. These complexes are diamagnetic and have square planar stereochemistry. The Pd(L₂)X₂ derivatives, are non-conductors, and have trans-structures except for the cis-Pd(N-EtIm)₂Br₂. The biological activity of water soluble Pd(II) compounds is also reported.     

Dinitrogen complexes of iron(II) with chelating agents as ligands

Two new dinitrogen compounds of formulae Na₂[Fe(EDTA)N₂].2H₂O and Na₂[Fe(CDTA)N₂].2H₂O have been synthesized from [Fe(H-EDTA)H₂O] and [Fe(H-CDTA)-H₂O], respectively, and NaN₃. Both complexes have been characterized by IR and electronic spectra. The thermal behaviour has been studied by TG and DTA techniques.     

Ruthenium(II) complexes with triphenylphosphine or triphenylarsine and other monodentate ligands

Synthesis and studies on some five-coordinate ruthenium(II) complexes, viz. [Ru(MPh₃)(C₆H₅CHO)₂Cl₂] and [Ru(MPh₃)₂(CO)Cl₂] (where M = P or As) have been described. Reactions of [Ru(MPh3)(C₆H₅CHO)₂Cl₂] with N,N-dimethylformamide, dimethylsulphoxide and pyridine and of [Ru(MPh₃)₂(CO)Cl₂] with pyridine are described.     

Synthesis and spectral studies of copper(II) complexes with amide group ligands

Complexes of copper(II) with 2-(acetylamino)benzoic acid, 2-(benzoylamino) benzoic acid, 2-(aminocarbonyl)benzoic acid, 2-[(phenylamino)carbonyl]benzoic acid, 2-[(1-naphthalenylamino)carbonyl]benzoic acid, 2-[(2-aminophenylamino)carbonyl]benzoic acid, 2-aminobenzanilide, 2(aminobenzoyl)benzoic acid, maleanilic acid and malea-1-naphthalanilic acid have been prepared and characterized by chemical analyses, molar conductivity, magnetic susceptibility measurements, thermal data, IR, electronic and ESR spectra. The visible and ESR spectral studies of these complexes (except those of maleanilic acid and malea-1-naphthalanilic acid) indicate that they are monomeric having either square planar or distorted octahedral geometry around Cu(II). The Cu(II) complexes of maleanilic acid and malea-1-naphthalanilic acid have been tentatively assigned dimeric structures. From the ESR spectra of Cu(II) complexes various parameters have been calculated.     

Four- and five-coordinate copper(II) complexes containing mixed ligands

New copper(II) complexes of general formula, Cu(ONS)B (ONS = the di-negatively charged Schiff base, S-benzyl-β-N-(2-hydroxyphenyl) methylendithiocarbazate; B = pyridine, 2,2′-dipyridyl or 1,10-phenanthroline) have been synthesized and characterised by magnetic and spectroscopic measurements. The complex, Cu(ONS)py is four-coordinate and square-planar. Magnetic and spectroscopic data support a five-coordinate, presumably, a trigonal-bipyramidal structure for the [Cu(ONS)dipy] and (Cu(ONS)phen] complexes     

3,3′-Dicarbomethoxy-2,2′-bipyridyl complexes of palladium(II), platinum(II) and rhodium(III)

3,3′-Dicarbomethoxy-2,2′-bipyridyl(DCMB)reacts with K₂MCl₄(M = Pd,Pt) to give M(DCMB)Cl₂ and with RhCl₃ to give the cis-[Rh(DCMB)₂Cl₂]⁺ ion. Attempts to prepare the tris (DCMB) complex with Rh(III) and analogous Co(III) complexes were unsuccessful.     

Metal complexes of some asymmetric diaminodiamide ligands—III1,2: Rates of conversion from octahedral to square planar complexes of Ni(II)

Dissociation of the two amide protons from complexes of asymmetric diaminodiamides with Ni(II) in aqueous solution occurs under moderately basic conditions. The loss of the protons is accompanied by a conversion of the complex from octahedral to square planar. The rates of conversion for complexes NiL²⁺ were measured spectrophotometrically and were found to depend linearly on [OH^?]. The diaminodiamide ligands used were S, R, S- and S, S, S-N, N′-dialanylpropylenediamine (DAPN), S, S-N, N′-dialanylethylenediamine (DAEN), R-N, N′-diglycylpropylenediamine (DGPN), and N, N′-diglycylethylenediamine (DGEN). The rates varied in the order SS-DAEN > DGEN > SRS-DAPN > R-DGPN ≈ SSS-DAPN.     

Manganese(II) and copper(II) complexes of some nitrogenoxygen and nitrogensulphur donor ligands

Manganese(II) and copper(II) complexes of the type M(ligandH)₂ with some nitrogenoxygen and nitrogensulphur donor ligands (HL) viz. phenylpyruvic acid semicarbazone (ppysc), 4-methylphenylpyruvic acid semicarbazone (4-mppysc), phenylpyruvic acid thiosemicarbazone (ppytsc) and 4-methylphenyl pyruvic acid thiosemicarbazone (4-ppytsc), have been synthesised. All the complexes have been characterised by magnetic moment measurements, IR electronic and electron spin resonance special studies. All the ligands behave as tridentate.     

Four-coordinated palladium(II) and platinum(II) complexes containing the Lewis-acid {M(S2CNHR)(PR3′)} group combined with a variety of other ligands

A new series of four-coordinated Pd(II) and Pt(II) complexes in which the Lewis-acid (14-electron) {M(S₂CNHR)(PR₃′)} group is combined with a variety of other ligands (such as RHNCS₂^?, I^?, SCN^?, SnCl₂I^?) has been synthesised and studied. The structures of the new compounds are discussed in relation to their specroscopic, magnetic and thermal properties. In the case of [M(S₂CNHR)₂(PR₃′)] complexes both the spectroscopic data (IR, ¹H NMR, UV-Vis) and their thermal behaviour strongly suggest the coexistence of two kinds of gem-disulphide ligands, one acting as a bidentate ligand and the other one as a unidentate. Also it was confirmed that the chemical behaviour of the bis(N-alkyldithiocarbamato) complexes of Pd(II) and Pt(II) towards tertiary phosphines is similar to that of the isoelectronic xanthate complexes rathe than to the bis(N,N-dialkyldithiocarbamato) complexes.     

Metal complexes of some asymmetric diaminodiamide ligands—II. Stabilities of complexes of nickel(II) in aqueous solution

Equilibria between a series of asymmetric diaminodiamides and Ni(II) in aqueous solution have been studied by potentiometric and spectrophotometric methods. The ligands were S,R,S- and S,S,S-N,N′-dialanylpropylenediamine (DAPN), S,S-N,N′-dialanylethylenediamine (DAEN), R-N,N′-diglycylpropylenediamine (DGPN), and N,N′-diglycylethylenediamine (DGEN). At lower values of pH the complexes NiL²⁺ and in some cases NiL²⁺₂ were formed. Spectral data indicated that both of these were octahedral. At higher pH the two amide protons were lost and square planar complexes were formed. The diastereomeric DAPN ligands showed stereoselectivity in the equilibrium constants for deprotonation and formation of the square planar complexes. Comparison of optical rotatory dispersion curves and absorption spectra for the various complexes permits partial assignment of structures.     

Synthesis and characterization of triorganoantimony(V) complexes with bidentate ligands

Monochelated organoantimony(V) complexes of the type R₃Sb(OMe)L, where R = Me or Ph, and L is the anion of acetylacetone, 8-hydroxyquinoline, salicylaldehyde, o-hydroxyacetophenone or 2-hydroxy-1-naphthaldehyde have been obtained from triorganoantimony(V) dibromide and the sodium derivative of the ligands in a benzene-methanol mixture. Molecular weight determination in benzene reveals the monomeric nature of these complexes. IR and NMR data suggest that L acts as a bidentate ligand giving an octahedral environment for the antimony atom.     

Transition metal complexes with 1,3-bis-(2-hydroxyphenyl)-1,3-propanedione—I : Mononuclear complexes

Reaction of 1,3-(2-hydroxyphenyl)-1,3-propanedione (BhPPH₃), a ligand with three possible sites of coordination acting as a chelating agent, with metal acetates results in the formation of mononuclear species M(BhPPH₂)₂S,S′ (M=Mn, Fe, Co, Ni, Zn; S,S′=CH₃OH, C₂H₅OH or H₂O); M′(BhPPH₂)₂ (M′=Cu, Pd), and M″(BhPPH₂)₃S,S′ (M″= Fe, Al). The complexes have been studied by ¹H-NMR when possible, and IR spectra. The position of the methine proton (=CH-) at 6.88 ppm in Zn(BhPPH₂)₂S,S′ indicates that BhPPH₃ behaves in mononuclear complexes as a common β-diketone. Most of the complexes lose S,S′ molecules on heating but a crystal structure of Zn(BhPPH₂)₂ · 2C₂H₅)OH indicates that the C₂H₅OH molecules are oxygen bonded to the metal centre.     

Carbonyl rhodium(I) complexes with α-diimines ligands

The reactions of [Rh(CO)₂Cl]₂ with α-diimines, RN=CR′-CR′=NR (R = c-Hex, C₆H₅, p-C₆H₄OH, p-C₆H₄CH₃, p-C₆H₄OCH₃, R′ = H; R = c-Hex, C₆H₅, p-C₆H₄OH, p-C₆H₄OCH₃; R′ = Me) in 2:1 Rh/R-dim ratio gave rise to ionic compounds [(CO)₂Rh.R-dim(R′,R′)][Rh(CO)₂Cl₂] which have been characterized by elemental analyses, electrical conductivity, ¹H-NMR and electronic and IR spectroscopy. Some of these complexes must involve some kind of metal-metal interaction. The complex [Rh(CO)₂Cl.c-Hex-dim(H,H)] has been obtained by reaction of [Rh(CO)₂Cl]₂ with the c-Hex-dim(H,H) ligand in 1:1 Rh/R-dim ratio. The reactions between [(CO)₂Rh.R-dim(H,H)][Rh(CO)₂Cl₂](R = c-Hex or p-C₆H₄OCH₃) with the dppe ligand have been studied. The known complex RhCl(CO)(PPh₃)₂ has been isolated from the reaction of [(CO)₂Rh.R-dim(H,H)]-[Rh(CO)₂Cl₂] (R = c-Hex or p-C₆H₄OCH₃) with PPh₃ ligand.     

Cyanato-copper(II) complexes with organic ligands—XXIV. Diisocyanato-bis(3,5-dimethylpyrazole)copper(II)—the cyanate member of the coligand isomer

The title compound was prepared, and found to be isomeric with the known bis(1-carbamoyl-3,5-dimethylpyrazolato)copper(II). Its IR, far-IR, electronic     

Nickel(II) complexes of phthalic hydrazide or its anion,and their reaction with oxygen and nitrogen-donor ligands

The reaction of phthalic hydrazide(H₂PH) with Ni(II) salts yields complexes of the type [NiHPH)₂(H₂O)₂]2H₂O(I). Reaction of this complex with acetylacetone(acac) and ethyl-enediamine(en) gives mononuclear complexes of type [NiHPH)(acac)₂(H₂O)]H₂O(II) and [Ni(HPH)₂(en)₃(H₂O)]H₂O(IV) respectively and with monoethanolamine (MEA), aniline(An) and p-phenylenediamine(p-Phda) it gives trinuclear complexes of type [Ni₃(PH)₇(MEA)₄ (H₂O)3H₂O(III), [Ni₃(HPH)₄(An)(H₂O)₇]H₂O(V) and [Ni₃(HPH)₅(p-Phda)(H₂O)₇]H₂O(VI) respectively. The complexes have been characterized on the basis of infrared and electronic spectra and magnetic properties as containing octahedral Ni(II) and anionic hydrazide ligand.Ligand field parameters have been calculated and compared with chromophores containing oxygen and nitrogen donor atoms. Analysis of electronic spectra, calculated Dq values and IR absorptions strongly indicate the presence of NiN₂O₄, NiNO₅, NiO₆ and NiN₃O₃ chromophores.