Studies on ruthenium(III), rhodium(III) and iridium(III) complexes of indazoles

Summary New complexes of the general formula M(L)₃Cl₃ and M(5-AInz)₂Cl₃ · n H₂O (where M = Ru^III, Rh^III and Ir^III; L = indazole and 5-nitroindazole; n=1–2) have been synthesized and characterised by elemental analysis, molar conductance, magnetic susceptibility and i.r. and electronic spectral measurements. All the complexes are covalent and apparently have an octahedral geometry. The ligands are monocoordinated through the pyrrole nitrogen. From the far i.r. spectra amer configuration has been assigned to the indazole and 5-nitroindazole complexes.     

The classification of trigonal bipyramidal platinum(II), rhodium(I) and iridium(I) olefin complexes

It is shown that trigonal bipyramidal platinum(II), rhodium(I) and iridium(I) olefin complexes are better classified with the platinum(O) complex [Pt(PPh₃)₂(C₂H₄)] as class T olefin complexes than with the square-planar platinum(II) complexes such as [Pt(C₂H₄)Cl₃]^- which fall in class S. The underlying reasons for this are considered to be electronic rather than steric as was previously suggested.     

Synthesis and infrared studies of Methylgallium(III) and Gallium(III) Complexes with Tridentate Ligands

Several new 1:1 complexes, neutral or anionic, formed by Methylgallium(III) and Gallium(III) with tridentate ligands (H₂L; ONO and SNO donor atoms), as well as a glycylglycine derivative, have been synthesized, and characterized in the solid state by infrared spectroscopy. Data have been interpreted in terms of trigonal bipyramidal type configurations of the environment of the metal centre, in the complex anions [Cl₂GaL]^? as well as in compounds CH₃GaL and ClGaL: in the latter two, dimerization would occur through bridging, three-coordinating oxygen atoms.     

Spectral and structural studies of cobalt(II,III), nickel(II), and copper(II) complexes of dehydroacetic acid N4-dialkyl- and 3-azacyclothiosemicarbazones

Co^II,III, Ni^II, and Cu^II complexes of new dehydroacetic acid N4-substituted thiosemicarbazones have been studied. The substituted thiosemicarbazones, N4-dimethyl-(DA4DM), N4-diethyl-(DA4DE), 3-piperidyl-(DApip) and 3-hexamethyleneiminyl-(DAhexim), when reacted with the metal chlorides, produced two Co^II complexes, [Co(DA4DE)Cl₂] and [Co(DAhexim)₂Cl₂]; two Co^III complexes, [Co(DA4DM-H)₂Cl] and [Co(DApip-H)(DApip-2H)]; a paramagnetic Ni^II complex, [Ni(DAhexim)(DAhexim-H)Cl]; three diamagnetic Ni^II complexes, [Ni(DA4DM-H)Cl], [Ni(DA4DE-H)Cl] and [Ni(DApip-H)Cl]; and four Cu^II complexes with the analogous stoichiometry of the latter three Ni^II complexes. These new thiosemicarbazones have been characterized by their melting points, as well as i.r., electronic and ¹H-n.m.r. spectra. The metal complexes have been characterized by i.r. and electronic spectra, and when possible, n.m.r. and e.s.r. spectra, as well as elemental analyses, molar conductivities, and magnetic susceptibilities. The crystal and molecular structure of the four-coordinate Cu^II complex, [Cu(DAhexim-H)Cl] has been determined by single crystal X-ray diffraction and the anionic ligand coordinates via an oxygen of the dehydroacetic acid and the thiosemicarbazone moiety's imine nitrogen and thione sulfur.     

Spectral,magnetic studies and molecular orbital calculations for (4,5-dimethyl-3-pyrazolyl)aldazine copper(II) complexes

Summary A new series of copper(II) complexes derived from (4,5-dimethyl-3-pyrazolyl) aldazine (DMPA), formulated as: (a) [LCuX₂]·nEtOH; (b) [LCu(H₂O)](ClO₄)₂; and (c) [LCuX]BF₄·nH₂O, where n = 1/2 or 1, X = Cl or Br and L = DMPA, have been synthesized. The formulations are based on elemental analyses and molar conductivity data. I.r., u.v.-vis., e.s.r. and magnetic data reveal that the complexes are trigonal bipyramidal, tetrahedral and stacked square-planar structures for (a), (b) and (c), respectively. The trigonal bipyramidal structure for class (a) compounds is confirmed using the atom superposition and electron delocalization-molecular orbital calculations, which agree with the experimental electronic spectral data. Variable temperature magnetic susceptibility data shows a ferromagnetic interaction within copper(II) complexes of class (c).     

Copper(II) complexes of isobutyl methyl ketone semicarbazone

Summary Copper(II) complexes of isobutyl methyl ketone semicarbazone have been prepared and characterised by magnetic moments, i.r., electronic and e.s.r. spectral studies. The complexes were found to have CuL₂X₂ and CuL₂X₂ · 2H₂O compositions. The electronic and e.s.r. spectra suggest a five-coordinated trigonal bipyramidal geometry, for the CuL₂X₂ complexes, (X=Cl^–, Br^–, NO ₃ ^– , and 1/2 SO ₄ ^2– ) and six-coordinate octahedral geometry has been suggested for CuL₂X₂ · 2H₂O (X=Cl^–, Br^–, NO ₃ ^– , SO ₄ ^2– ).     

Synthesis,characterization and catalytic studies of iron(III), cobalt(II), nickel(II) and copper(II) complexes containing triphenylphosphine and β-diketones

A series of new β-diketonato complexes have been synthesized from the reactions of iron(III), cobalt(II), nickel(II) and copper(II) Ph₃P complexes with β-diketones (acetylacetone, benzoylacetone and dibenzoylmethane). All the complexes have been characterized by elemental analyses, spectral studies (i.r., electronic., magnetic., e.p.r., ¹H-n.m.r.) and cyclic voltammetry. The new complexes have been used as catalysts for aromatic coupling and oxidation reactions. Higher catalytic activity has been observed for the nickel(II) complexes compared to the other complexes.     

Synthesis and characterization of Ru(III), Rh(III), Pt(IV) and Ir(III) thiosemicarbazone complexes

Ru(III), Rh(III), Pt(IV) and Ir(III) complexes of 2-furfural thiosemicarbazone as ligand have been synthesised. These complexes have the composition [M(ligand)₂X₂]X (M = Ru(III) Rh(III) and Ir(III) X = Cl and Br) and [Pt(ligand)₂ X₂] X₂ (X = Cl, Br and 1/2SO₄). The deprotonated ligand forms the complexes of the formulae M(ligand-H)₃ and Pt(ligand-H)₃Cl. All these complexes have been characterized by elemental analysis, magnetic measurements, electronic and infrared spectral studies. All the complexes are six-coordinate octahedral.     

Semicarbazone and thiosemicarbazone chromium(III) complexes

Summary Chromium(III) complexes, [Cr(ligand)₂]Cl, containing the semicarbazones and thiosemicarbazones of 2-hydroxyacetophenone and 2-hydroxynaphthaldehyde, and [Cr(ligand)₂Cl₂]Cl, formed from 4-hydroxyacetophenone semicarbazone and thiosemicarbazone, have been synthesized. The complexes were characterized by elemental analysis, conductance, magnetic moment, i.r., electronic and e.s.r. spectral studies. On the basis of physicochemical investigations tetragonal geometries are assigned to the complexes.     

NS and NSO-Donor ligands and their metal complexes. Synthesis and characterisation of a new low-spin iron(III) complex with 1,2-di(o-aminophenylthio)ethane and iron(III), cobalt(III) and manganese(III) complexes of 1,2-di(o-salicylaldiminophenylthio)ethane

Summary Iron(III) complexes of a quadridentate N₂S₂ donor ligand, 1,2-di(o-aminophenylthio)ethane (DAPTE) and its Schiff Base with salicylaldehyde, a hexadentate N₂S₂O₂ donor ligand,viz. 1,2-di(o-salicylaldiminophenylthio)ethane (H₂DSALPTE) have been synthesised and characterised.The Schiff base ligand (1 mol) gave a dark green tri-iron(III) [Fe₃(DSALPTE)(HDSALPTE)Cl₃]Cl₂ complex when reacted with anhydrous iron(III) chloride (1 mol). The Mössbauer data of this complex suggest the presence of three iron sites, one of which is octahedral and the other two tetrahedral. On the other hand, Fe(ClO₄)₃ reacted smoothly with H₂DSALPTE in ethanol to give a mononuclear pseudo-octahedral complex in which the ligand functions in a dibasic hexadentate fashion. Mössbauer data suggest the presence of a low-spin-high-spin equilibrium in the solid state. The manganese(III) and cobalt(III) complexes of the Schiff base, H₂DSALPTE, are also studied for the sake of comparison with the corresponding iron(III) complex. The N₂S₂ ligand, however, formed a low-spin pseudo-octahedral iron(III) complex. The complexes have been characterised by elemental analysis, molar conductance values, cryomagnetic data and i.r., electronic and Mössbauer spectral data.     

Synthesis and spectral studies ofo-hydroxyacetophenone (N-benzoyl)glycyl hydrazone and some of its lanthanide(III) complexes

Summary o-Hydroxyacetophenone (N-benzoyl)glycyl hydrazone (o-HABzGH) has been characterized by i.r.,¹H n.m.r.,¹³C n.m.r. and mass spectral studies, and its complexes of the types [Ln(o-HABzGH)Cl₂(H₂O)₂]Cl and [Ln(o-HABzGH–2H)OH(H₂O)₃], where Ln=La, Pr, Nd, Sm and Eu, have been synthesized. The structures of the complexes have been studied by conductance, magnetic, electronic, i.r.,¹H n.m.r. and¹³C n.m.r. spectral techniques. The hypersensitive bands of the electronic spectra suggest coordination numbers six and seven around Nd^III in its adduct and neutral complexes respectively. I.r. and n.m.r. spectral data suggest a neutral bidentate behaviour for the ligand in the adducts and a dinegative tridentate nature in the neutral complexes.     

Mixed ligand complexes of ruthenium(III), rhodium(III) and iridium(III) with dipicolinic acid and some monobasic bidentate nitrogen,oxygen donor ligands

The trivalent ruthenium, rhodium and iridium complexes of dipicolinic acid and its mixed ligand complexes with several nitrogen, oxygen donor molecules, of types: Na[M(dipic)₂]·2H₂O and [M(dipic)(N-O)]·nH₂O (where M = Ru(III), Rh(III) or Ir(III); dipicH₂ = dipicolinic acid; NOH represents different nitrogen, oxygen donor molecules, viz., picolinic acid, nicotinic acid, isonicotinic acid, glycine, aminophenol, o- or p-aminobenzoic acid), have been synthesized and characterised on the basis of elemental analyses, electrical conductance, magnetic susceptibility measurements and spectral (electronic and infrared) data. The parent dipicolinic acid complexes are found to have a six-coordinate pseudooctahedral structure, whereas for mixed ligand complexes, a polymeric six-coordinate structure has been assigned. Various ligand field and nephelauxetic parameters have also been evaluated.     

Spectral and magnetic studies on normal cobalt(II) planar and cobalt(III) octahedral, spin-crossover cobalt(III) octahedral and planar-tetrahedral cobalt(II) carbodithioates

Five cobalt(II) complexes, a normal complex Co(4-PPipzcdt)₂ (4-PPipzcdt = 4-phenylpiperazine-1-carbodithioate), and four zwitterionic complexes, Co(4-PPipzcdtH)₂X₂ and Co(4-MPipzcdtH)₂X₂ (X = Cl, Br; 4-PPipzcdtH = 4-phenylpiperazine-1-carbodithioic acid, 4-MPipzcdtH = 4-methylpiperazine-1-carbodithioic acid), have been synthesized. Normal cobalt(III) complexes of the type Co(4-MPipzcdt)₃ and Co₂ {2-MPipz(cdt)₂}₃ (2-MPipz(cdt)₂ = 2-methylpiperazine-1,4-dicarbodithioate) and two zwitterionic cobalt(III) complexes of the type Co(4-MPipzcdtH)₃X₃ (X = Cl, Br) have also been obtained. In addition to the room temperature IR and electronic spectra and magnetic susceptibility studies, all the complexes, except the normal Co(4-MPipzcdt)₃ and Co(4-PPipzcdt)₂ and zwitterionic Co(4-MPipzcdtH)₃Cl₃, have been investigated by variable-temperature magnetic susceptibility measurements. The results of the variable-temperature magnetic susceptibility studies suggest that two cobalt(II) carbodithioates exhibit a square planar-tetrahedral equilibrium, while two cobalt(III) octahedral carbodithioates show a spin-crossover phenomenon.     

Supramolecular structures and properties models of macrocyclic polymer complexes

Two novel supramolecular complexes of types [Ru(L)(H₂L)Cl·OH₂] and [Ru(HL_n)Cl₃] (where H₂L is a potential tetradentate ligand derived from hydrazine hydrate and diethyl malonate, and HL_n is a potential bidentate ligand derived from coupling of allyl azo‐β‐diketone) have been synthesized and characterized by elemental analysis, conductance and magnetic measurements, followed by ¹H NMR, to determine the effect of substituents on the intramolecular hydrogen bond. The electronic properties and models of the bonding of ligands and complexes were investigated by UV–Vis and IR spectroscopies. The first type of complex contains terminal hydrazinic nitrogen atoms with an unshared electron pair and may take part in nucleophilic condensations. Therefore, the reactions of allyl‐β‐diketone complexes with malonic dihydrazide have also been studied, as these cause ring closure and formation of supramolecular macrocyclic ligand complexes. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory, and various parameters have been evaluated. On the basis of the electronic spectra, an octahedral geometry has been established for the polymer complexes C. The macrocyclic polymer complexes D are pentacoordinate, and a trigonal‐bipyramidal environment (D_3h) is suggested for the ruthenium(III) ion. The effect of the Hammett constant on the ligand field parameters is also discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

Matrix effects in fast atom bombardment mass spectrometry of cationic iridium(III) and rhodium(III) coordination complexes

Fast atom bombardment mass spectra of cationic iridium(III) and rhodium(III) coordination complexes (M⁺Cl₂L₂, X^?; where the ligand L is a dinitrogenous aromatic system) have been obtained with thioglycerol, glycerol or tetraglyme as a matrix. Two kinds of reactions, initiated by particle bombardment, have been discovered between these complexes and the matrix. First, with thioglycerol one or two chlorine atoms are substituted by a thioglycerol radical, more rapidly for rhodium compounds; secondly, when the ligand L possesses a diazo function, this function is hydrogenated depending on the ability of the matrix to generate hydrogen radicals by bombardment.     

Schiff base derivatives of lanthanons,La(III), Pr(III), Nd(III) and Sm(III) complexes of bifunctional tetradentateSchiff base

Reactions of La(III), Pr(III), Nd(III) or Sm(III) nitrate with bifunctional tetradentateSchiff base, [o-HOC₆H₄C(CH₃): :NCH₂]₂, having the donor system HO–N–N–OH in 12 molar ratio have been investigated and found to yield new derivatives of the type [Ln(SBH₂)₂](NO₃)₃ [whereLn=La(III), Pr(III), Nd(III) or Sm(III) andSBH₂=Schiff base molecule, [o-HOC₆H₄C(CH₃) : NCH₂]₂. On the basis of elemental analyses, conductivity and magnetic measurements and infrared spectra, plausible structures for the resulting complexes have been indicated.     

Hydroxamic acid dinuclear complexes of molybdenum(V) and molybdenum(III)

Summary Molybdenum(V) and molybdenum(III) complexes [Mo₂O₃L₄] and [Mo₂L₆] derived from hydroxamic acids (HL) were prepared and identified by Raman, i.r., e.s.r., electronic spectra and analytical data. The low magnetic moments of the dinuclear complexes are due to in part to intramolecular interactions. Electronic spectra and vibrational studies indicate the presence of a Mo₂O₃ core in the molybdenum(V) complexes. The relative intensities of the, main and satellite peaks in e.s.r. spectra indicate the dinulcear nature of molybdenum(III) hydroxamates.     

Oxovanadium(IV), manganese(II) and manganese(III) carbodithioates exhibiting abnormal magnetic behaviour

Summary New carbodithioate complexes of the oxovanadium(IV), manganese(II) and manganese(III) ions have been prepared and studied by i.r. and electronic spectral and variable temperature magnetic susceptibility (77K to room temperature) measurements. The carbodithioate ligands, 4-methylpiperazine-1-carbodithioate (4-MPipzcdt) and 4-phenylpiperazine-1-carbodithioate (4-PPipzcdt), were derived from heterocyclic secondary amines. The VO(4-MPipzcdt)₂ and VO(4-PPipzcdt)₂ complexes possess C _4v symmetry; Mn(4-PPipzcdt)₂ is tetrahedral and Mn(4-PPipzcdt)₃ is octahedral. All exhibit abnormal room temperature magnetic moments and the variable temperature magnetic moments suggest antiferromagnetism for the oxovanadium(IV) and the manganese(II) complexes and the occurrence of low spin (³ T _1g ) high spin (⁵ E _g ) equilibrium in addition to antiferromagnetic interactions in the manganese(III) complex. The spin-spin exchange parameter (-2J) value for the VO(4-MPipzcdt)₂ complex has been calculated using variable temperature magnetic susceptibility data.     

N/P-ethoxyphenyl/dithiocarbamato complexes of Au(III), As(III), Fe(III), Co(III) and Mo(V)

The complexes of Au(III), As(III), Fe(III), Co (III) and Mo(V) with N(p-ethoxyphenyl)-dithiocarbamate have been synthesized and characterized on the basis of elemental analyses, conductance measurements, infrared and electronic spectra, molecular weight determinations and magnetic moment data. The thermal behaviours of these complexes have been studied with the aid of TG and DTA techniques.     

Studies on mixed ligand complexes,part 4. Cobalt(III) heterochelates containing trimethylenediamine and some bidentate NN,NO and OO donor ligands

Summary A series of new diamagnetic cobalt(Ill) mixed ligand complexes having general formula [Co(AA)(tn)₂]ⁿ⁺ (where AA = biguanide, picolinic acid, acetoacetanilide, benzoylacetanilide,m-nitrobenzoylacetanilide, acetylacetone,N-benzoylphenylhydroxylamine and malonic acid, tn = trimethylenediamine and n = 1–3) have been synthesized and characterized by elemental analysis, conductance measurements, electronic spectra, i.r. spectra, equivalent weight and magnetic measurements. The electronic spectra are typical of octahedral cobalt(III) complexes. The effect of cationic charge and the nature of the ligands on the R_f values of the complexes have been determined by paper chromatography.Author to whom all correspondence should be directed.