Palladium(II) halide complexes with 2,5-dimethyl-, 2-amino-, 2-amino-5-methyl-, 2-ethylamino- and 2-mercapto-5-methyl-1,3,4-thiadiazole

Some palladium(II) halide complexes with 2,5-dimethyl- (DTZ), 2-amino- (ATZ), 2-amino-5-methyl- (MATZ), 2-ethylamino- (EATZ) and 2-mercapto-5-methyl-1,3,4-thiadiazole (MTTZ) have been prepared and studied: PdX₂ · 2L (L = DTZ, ATZ, MATZ : X = Cl, Br, I; L = EATZ: X = Br, I; L = MTTZ: X = I), PdCl₂ · 2.5EATZ, PdCl₂ · 3MTTZ, PdBr₂ · 1.5MTTZ and PdX₂ · L (L = DTZ, ATZ, MATZ, EATZ: X = Cl, Br; L = MTTZ: X = Cl(H₂O), Br). In the PdX₂ · 2L, PdCl₂ · 2.5EATZ and PdCl₂ · 3MTTZ complexes the palladium ions are cis-(2X, 2L)-coordinated, the coordination sites being N_ring for DTZ, NR₂ for ATZ, MATZ, EATZ and C = S for MTTZ. PdBr₂ · 1.5MTTZ may be formulated as cis[PdBr₂-2L] · [PdBr₂ · L]. In the PdX₂ · L complexes the ligand very likely acts as bidentate by using a ring-nitrogen atom as the second coordination site.     

Copper(II) complexes of thiosemicarbazones derived from 2-acetylpyridine and its n-oxide

A series of Cu(II) complexes of the thiosemicarbazone, 3-azabicyclo[3.2.2]-nonene-3-thiocarboxylic acid 2-[1-(2-pyridinyl)ethylidene]hydrazide(HL) and the corresponding N-oxide (HLO) have been prepared and characterized. Both ligands undergo deprotonation and appear to coordinate via the thione sulfur, the imine nitrogen and the pyridyl nitrogen (or N-oxide oxygen). A single anionic ligand such as Cl^?, Br^?, NCS^? and N^?₃ completes the bonding to the Cu(II) center of these 4-coordinate complexes. When the complexes are prepared using Cu(II) perchlorate, the solids isolated contain a neutral thiosemicarbazone ligand as well as the deprotonated ligand. The solids are primarily characterized by IR, electronic and electron spin resonance spectroscopy. In addition, electronic and ESR spectra of their chloroform solutions were recorded. Most of the solids (except the nitrates) were unaltered upon dissolution. Simulation of the solution ESR spectra was used to estimate the coupling constants of the various coordinated nuclei.     

Carbonyl-organocobalt(I) and -(II) complexes

Passage of CO through solutions of complexes (C₆F₅)₂CoL₂ gives carbonyl derivatives (C₆F₅)₂CoL₂(CO) (L₂ = 2 PEt₃, 2 P-n-Bu₃, 2 PPh₃, Ph₂PCH₂CH₃PPh₂). The properties of these compounds are described.The compounds are also produced by treating solutions of (C₆F₅)₂Co-(dioxane)₂ with CO, but a simultaneous reduction to (C₆F₅)Co(CO)₄ takes place. Treatment of the latter complex with monodentate ligands gives substitution products (C₆F₅)Co(CO)₃L (L = PEt₃, P-n-Bu₃, PPh₃) all of which are monomeric, whereas the addition of Ph₂PCH₂CH₂PPh₂ gives the dimer (C₆F₅)(CO)₂CoLLCo(CO)₂(C₆F₅). The properties of these compounds are discussed.     

Metal complexes of mercaptoamines—I. Synthesis and crystal and molecular structure of tetrakis (3-amino-1-propanethiolato) trinickel(II)chloride

The reaction of nickel(II)chloride with γ-mercapto-propylamine in ethanolic solution gives the complex [Ni₃(MPA)₄]Cl₂(MPA=NH₂-(CH₂)₃-S). The complexes [Ni₃(MPA)₄]X₂(X=Br, I, ClO₄) can be synthesized from the chloride complex by addition of the sodium salt in aqueous solution. The crystal structure consists of discrete divalent trinuclear cations and chloride anions. Each sulphur atom of the ligand acts as a bridge between two nickel atoms, and the nitrogen atoms complete the coordination around the terminal nickel atoms. The geometry around the metal atoms is square-planar. The electronic and IR spectra of the complexes [Ni₃(MPA)₄]X₂(X=Br, I, ClO₄) indicate that all these compounds are composed of the [Ni₃(MPA)₄]²⁺ and X^? ions.     

Spectroscopic studies of 4-substituted pyridinium 2-pyridylcarbonylmethylide-rhodium(I) complexes and x-ray molecular structure of (1,5-cyclooctadiene) (4-methylpyridinium 2-pyridylcarbonylmethylide)rhodium(I) perchlorate

(1,5-Cyclooctadiene) (4-substituted pyridinium 2-pyridylcarbonylmethylide)- rhodium(I) perchlorates, [Rh(COD)(C₅H₄NC(O)C?H₊C₅H₄X-4)]ClO₄ [COD = 1,5-cyclooctadiene; X = CH₃C(O), CH₃OC(O), C₆H₅, CH₃, and H], have been prepared. They are shown to have the geometry with coordination by the pyridyl nitrogen and carbonyl oxygen atoms of the ylide ligands and to exhibit intramolecular rearrangement of coordinated COD in chloroform, methanol, and dimethyl sulphoxide based on IR and ¹H NMR spectroscopies. Although the ylides have exhibited fluorescence bands due to an intramolecular charge-transfer transition and phosphorescence bands due to a carbonyl ³(n?π^*) transition, the complexes have given emission bands due to the metal-to-ylide ligand charge-transfer transition. A.single crystal X-ray crystal structure has been determined for [Rh(COD)(C₅H₄NC(O)C?H₊C₅H₄CH₃-4)]ClO₄. The crystals are monoclinic, space group P2₁/n with cell dimensions a = 14.887(3), b = 20.274(4), c = 6.966(1) Å, β = 96.13(1)°, and Z = 4. The structure has been refined by a block-diagonal least-squares method to final R = 0.060 for 2997 independent reflections with |F_o| > 3σ(F). The ylide carbon-pyridinium nitrogen bond distance is 1.420(10) Å. The bonded distances from rhodium to the midpoints of the double bonds of COD are 1.982(11) and 2.014(12) Å.     

Copper(II) complexes of diaminodiamides in aqueous solution

The basicity constants of N,N′-bis(β-carbamoylethyl)ethylenediamine, N,N′-bis(β-carbamoylethyl)trimethylenediamine, N,N′-bis(β-carbamoylethyl)-1,2-propylenediamine, and N,N′-bis-(β-carbamoylethyl)-2-hydroxyltrimethylenediamine were determined potentiometrically in 0.10 mol dm^?3 NaNO₃ at 25.0°C. The formation of Cu(II) complexes of these ligands and the CuO to CuN bond rearrangements at the two amide sites of these complexes were investigated quantitatively by potentiometric and spectrophotometric techniques under the same conditions. Electronic spectra of the Cu(II) complexes of these ligands and their deprotonated species formed in aqueous solution were measured and discussed.     

Copper(II) and nickel(II) complexes of a neutral pentadentate Schiff base

A new pentadentate Schiff base 2,6,10-triaza-1,11-bis(2′-aminophenyl)-undeca-1,10-diene, abaDPT, and its complexes of general formula M(abaDPT)X₂ where M = Cu(II), Ni(II), X = Cl, Br, I, NO₃ and ClO₄, have been prepared. The complexes have been characterized by electronic and IR spectra, EPR, magnetic moments, molar conductances, and elemental analysis. IR data show an interaction between halide anion of the outer coordination sphere and the complexed amino group. EPR and spectrophotometric data of most of the copper compounds are consistent with a distorted square pyramidal geometry. Single crystal EPR studies of Cu(abaDPT)(NO₃)₂ and Cu(abaDPT)Br₂ revealed that copper atoms in the former compound occupy two magnetically inequivalent places in the lattice while copper atoms in the latter compound take identical sites. Principal g tensor axes of the two compounds have been determined.     

Copper(I) phosphine hydroborate complexes: A study involving hydroborates containing a BO bond

A study was made of the reactions between chlorotris(methyldiphenylphosphine)copper(I) and several hydroborates containing a boron-oxygen bond. The new complex ((acetoxy)trihydroborato)tris(methyldiphenylphosphine)copper(I) (Ph₂MeP)₃CuH₃B(O₂CCH₃) was isolated and characterized by analysis, IR, and NMR data. Analogous reaction conditions using HB(OR)₃^? anions did not give a BH containing product nor did several other anions of the general type HBR₃^?. The ability of the hydroborate to complex is related to the Lewis acidity of the respective borane attached to H^?.     

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.     

Complexes of 4-methoxy-2-(5-methoxy-3-methyl-pyrazol-1-yl)-6-methylpyrimidine,an anti-inflammatory agent—I. Copper(II) perchlorate complexes

The preparation and properties of copper(II) complexes of 4-methoxy-2-(4-methoxy-3-methyl-pyrazol-1-yl)-6-methylpyrimidine, are reported. Complexes of     

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.     

Rhodium(I) and rhodium(III) arene complexes with N-carbazolyltriphenylphosphinegold(I) and other polycyclic arene ligands

The new heteronuclear arene complexes [(COD)Rh(μ-cbz)AuPPh₃]ClO₄, [{(COD)Rh}₂(μ-cbz)AuPPh₃](ClO₄)₂, [(C₅Me₅)Rh(μ-cbz)AuPPh₃](ClO₄)₂ and [{C₅Me₅) Rh}₂(μ-cbz)AuPPh₃](ClO₄)₄ (COD = 1,5-cyclooctadiene, cbz = carbazolyl), and the mononuclear arene complexes [(COD)Rh(arene)]ClO₄ (arene = tetralin, biphenyl, fluorene, indene, 9,10-dihydroanthracene or carbazole) have been prepared by reaction of the acetone solvated complexes [(COD)Rh(Me₂CO)_x]ClO₄ or [(C₅Me₅)Rh(Me₂CO)₃](ClO₄)₂ with (cbz)AuPPh₃ or the appropriate polycyclic arene ligand.     

The interaction of morpholine with metal ions—I: Copper complexes

The synthesis and electronic and IR spectra of CuL₂(NO₃)₂ and CuL₄(NO₃)₂, where L stands for morpholine, are described. The thermal behaviour of the complexes is also discussed. The solids contain distorted octahedral Cu(II) bonded to morpholine through nitrogen only. In aqueous solutions only the species CuL₃(aq)²⁺ is stable in the concentration range 0.5 < [L] < 2 mol dm^?3, its stability constant being log K₃ = 14.64 ± 0.15 at 25.00°C and ionic strength 1 mol dm^?3; at very high morpholine concentrations, 3.4 < [L] < 6 mol dm^?3, evidence is also found for CuL₄(aq)²⁺, the value log K₄ = 15.5 being estimated. The aggressiveness of morpholine-H₂O₂ towards metallic copper is compared with that of ammonia-H₂O₂, both on thermodynamics and kinetics grounds; experimental results seems to be dominated by kinetics factors. The relevance of these results to water treatment in secondary systems of nuclear power reactors is discussed.     

Synthesis,characterisation and reactions of pentacoordinated iridium(I) complexes

Stable, pentacoordinated iridium(I) complexes have been synthesised by the replacement of the chlorine in IrCO(PPh₃)₂Cl by bidentate chelating ligands such as β-diketones, N-benzoyl-N-phenyl hydroxylamine, salicylaldehyde, 8-hydroxyquinoline, 2-hydroxybenzophenone and 2-hydroxy 4-methoxybenzophenone. Most of them gave stable oxygen adducts IrCO(PPh₃)₂(L)O₂ and all of them underwent oxidative addition with bromine in methylene chloride giving IrCO(PPh₃)₂(L)Br₂. These chelated iridium(I) compounds reacted with liquid sulphur dioxide to produce two types of SO₂ insertion products.     

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.     

Preparation and study of silver maleonitriledithiolate complexes

This paper reports the reaction of Ag₂(mnt) and [(NEt₄)Ag(mnt)] (mnt^2? = maleonitriledithiolate) with PPh₃ and 1,2-bis(diphenylphosph     

Synthesis and characterisation of ReOCl3(DTO)2 and ReOCl3(MBT)2 complexes

New complexes of Re(V) with dithiooxamide and 2-mercaptobenzothiazole with the general formula ReOCl₃L₂, were prepared starting from potassium perrhenate. The compounds were characterised by chemical analysis, optical spectra and magnetic susceptibilities.     

Coordination chemistry of new sulphur containing ligands—26. Eight coordinate vanadium(IV) and molybdenum(IV) complexes of 2-amino-1-cyclopentenedithiocarboxylate1

The new difunction ligand, 2-amino-1-cyclopentenedithio-carboxylate(L), was prepared and its coordination chemistry examined to gain further insight into the reactivity of “aromatic” dithio type ligands. Reaction with MoCl₄py₂ and VOSO₄, led to the surprising eight coordinate products ML₄. The sp² hybridization of the ring carbon to which the CS₂ moiety is bonded apparently yields a pseudo-aromatic effect on the reactivity of this ligand. The physical properties of these new compounds are discussed.     

Cyclic voltammetric studies of copper(II) dipeptide complexes. Evidence for copper(I) dipeptide complexes in aqueous media

The reduction of the title complexes was studied by cyclic voltammetry in aqueous media. It proceeds through a one-electron process generating intermediate copper(I) dipeptide complexes. The copper(I) dipeptide complexes are found to be short-lived and undergo transformations eventually generating Cu⁰ at the mercury electrode. The unchanged fraction of the copper(I) species is re-oxidised to the copper(II) complexes. The Cu⁰ generated undergoes a two-electron oxidation at a more anodic potential than the copper(I) complexes. pH-dependence of the title complexes is also investigated by cyclic voltammetry.     

Copper(II) complexes of 4-chloro,3-methyl,5-phenylisoxazole

4-chloro,3-methyl,5-phenylisoxazole copper(II) complexes of the type Cu(L)X₂(X = Cl, Br, NO₃) and Cu(L)₂(ClO₄)₂ have been prepared and studied by the IR, electronic, paramagnetic resonance spectroscopy and molar conductivity values. The ligand acts as monodentate N-bonded except to the nitrate derivative where this behaves as bridging bidentate. The halide complexes are tetrahedral, while the nitrate and perchlorate derivatives are square planar.