Resonance Raman spectra of tris(acetylacetonato)iron(III) and ruthenium(III) complexes and their solvent effect

The resonance Raman spectra of tris(acetylacetonatoiron(III)) and ruthenium(III) complexes in various solvents and in water-acetonitrile (W-AN) mixtures were measured. The resonance Raman spectra of both complexes indicated peaks near 460 and around 1580 cm^–1. Thev(C-O) peak (around 1580 cm^–1) is shifted to low frequency with an increase in the dielectric constant _T of the solvents, whereas thev(M-O) (M=Fe and Ru, near 460 cm^–1) are constant, independent of _T. It implies that the C-O bond in the acac^– ligand is lengthened by the polarizability effect of the solvents, while both the Fe-O and Ru-O bonds, which are located in the inside of the complexes, are not influenced by the solvents indicating that the interaction does not depend on the properties of individual solvent molecules but on those of the aggregate.     

Cobalt(II) and nickel(II) chloride and bromide complexes of 2-(2′-methyl-8′-quinolyl)benzoxazole and 2-(2′ or 4′-methyl 8′-quinolyl)benzimidazole

Summary Cobalt(II) and nickel(II) halide complexes of the ligands 2-(2-methyl-8-quinolyl)benzoxazole (mqbo), 2-(2-methyl8quinolyl)benzimidazole (mqbi) and 2-(4-methyl-8-quinolyl)benzimidazole (mqbi) were synthesized and characterized by analytical, thermogravimetric, conductivity and magnetic data, and i.r. and electronic spectra.The ligands are bidentate N-donors yielding complexes where the coordination geometry depends on the metal ion and steric hindrance. All the cobalt complexes have formula [CoL₂X₂] and distorted tetrahedral geometry. Different types of nickel compounds were obtained: i) complexes of formula NiLX₂ · n H₂O (or EtOH) (L = mqbo or mqbi; n=0–1.5) which arepseudo-tetrahedral or five-coordinate and ii) complexes NiL₂X₂ · n H₂O (L = mqbi, n=3 or 4) where the metal is bound to four nitrogen atoms and the overall coordination geometry is tetragonal. The structural changes occurring after removal of water or alcohol from the complexes are also reported.     

Indium(III) complexes with some salicylidene aromaticSchiff bases

In(III) complexes with salicylidene aromaticSchiff bases have been prepared. The nature of the complexes has been studied by microanalysis of the solid complexes, conductometric titration, uv and ir spectrophotometric measurements. The complexes are of the type 11 and 21 [Ligand: In(III)] depending upon theSchiff base. The tendency of the salicylideneSchiff base molecule towards complex formation with In(III) is found to depend largely on the strength of the intramolecular hydrogen bond established between the aldehydic OH group and C=N. Furthermore, it is concluded that theseSchiff bases cordinate to In(III) as tri- or bidentate ligands depending upon the molecular structure of theSchiff base (not as monodentate ligand as previously described). The high molar absorbance of the 12 In(III) complex with salicylidene-o-hydroxyaniline I (17,800 mol^–1 cm²) can be applied for the micro determination of small amounts of Indium as low as 0.57 g/ml solution.

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Indium(III)-Komplexe mit aromatischen Schiff-Basen

Zusammenfassung Es wurden einige In(III)-Komplexe mit (von Salicylaldehyd hergeleiteten)Schiff-Basen hergestellt. Elementaranalyse, konduktometrische Titration und UV- sowie IR-Spektroskopie wurden zur Aufklärung der Komplexe herangezogen. Es werden je nach verwendeterSchiff-Base 11-oder 21-Komplexe gebildet. Die Bildungstendenz der Komplexe mit denSchiff-Basen als drei- oder zweizähnige Liganden hängt weitgehend von Stärke und Ausbildungsmöglichkeit von H-Brückenbindungen ab. Einer der beschriebenen Komplexe ist zur photometrischen Mikrobestimmung von In(III) geeignet.

     

Far infrared spectra (500–50 cm−1) of the 2,2′-bipyridine complexes of palladium and platinum halides

Summary The far-i.r. spectra of the title complexes have been examined. Band assignments are based on the shifts induced by ligand deuteration and halide substitution. Deuteration of bipyridine causes large shifts ( >10 cm^–1) in internal ligand modes, intermediate shifts between 2 and 9 cm^–1) in metal-nitrogen stretching and bending modes and small to zero shifts in metal-halide stretching and bending vibrations. Generally, the requirements for square planarC _2v synanetry [two (M–N) and two (M–X) bands] are observed. Previous ambiguities in the assignment of the (M–N) bands have been resolved by the isotopic labelling technique employed in this study.     

Preparation and characterization of divalent metal ion complexes ofN-2-picolyl-N-phenylthiourea

Summary New complexes ofN-2-picolyl-N -phenylthiourea (HPPT) have been prepared employing a number of different divalent metal ion salts. The resultant Co^II, Ni^II, and Cu^II complexes, which generally involve coordination of HPPT, except for the Cu^II halides which have a deprotonated ligand, have been characterized by partial elemental analysis, molar conductivity and spectral (i.r., u.v.-vis., and e.s.r.) studies. HPPT is an NN bidentate ligand while the deprotonated form serves as an NNS bridging tridentate ligand. The complexes undergo partial or total decomposition in the solvents in which they are soluble. The compounds [Cu(HPPT)₂X₂] have resolved g features in their powder spectra indicating that magnetic dilution has occurred.On leave from Mansoura University, Mansoura, Egypt.     

Cyanato-Kupfer(II)-Komplexe mit organischen Liganden, 3. Mitt.: Darstellung,magnetische Suszeptibilität und Elektronenspektren der Cyanato-Kupfer(II)-Komplexe mit methylsubstituierten Pyridinen

Zusammenfassung Neue Cyanato-Kupfer(II)-Komplexe des Typs Cu(NCO)₂ L ₂ wurden bereitet, wobeiL -, - bzw. -Picolin, 2,4-Lutidin, 2,6-Lutidin oder 2,4,6-Collidin bedeutet; ferner Komplexe des Typs Cu(NCO)₂ L, wobeiL -Picolin oder 2,4-Lutidin ist. Ihre magnetische Suszeptibilität wurde bei verschiedenen Temperaturen gemessen und ihre Diffusions-Reflexionsspektren wurden dargestellt. Auf Grund der ermittelten magnetischen und spektralen Daten wird den Komplexen Cu(NCO)₂ L ₂ tetragonale Struktur verschiedenen Distorsionsgrades zugesprochen; der sterische Effekt der -methylsubstituierten LigandenL wird diskutiert. Die magnetischen und spektralen Eigenschaften der Komplexe Cu(NCO)₂ L hingegen deuten auf eine ungewöhnliche Art der Koordination.

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Cyanato copper(II) complexes with organic ligands, III: Preparation, magnetic susceptibility, and electronic spectra of the cyanato copper(II) complexes with methyl substituted pyridines

New cyanato copper complexes of the type Cu(NCO)₂ L ₂ have been prepared, whereL represents -, - or -picoline, 2.4-lutidine, 2.6-lutidine or 2.4.6-collidine. In a further series of complexes, Cu(NCO)₂ L, L represents -picoline or 2.4-lutidine. Their magnetic susceptibilities were determined at various temperatures and their diffusion-reflection spectra measured. On the basis of these data a tetragonal structure with varying degrees of distortion is assigned to the complexes Cu(NCO)₂ L ₂, and the steric effect of the -methyl-substituted ligandsL is discussed. The magnetic and spectral properties of the complexes Cu(NCO)₂ L indicate, however, a rather unusual kind of coordination.

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Mit 4 Abbildungen

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Teil der Habilitationsschrift vonJ. Kohout, Slowakische Technische Hochschule, Bratislava 1970.     

Transition metal complexes with 2-methyl-, 3-methyl-, and 4-methyl-piperidine dithiocarbamate as ligands

Summary A new series of manganese(III), cobalt(II), nickel(II), zinc(II), cadmium(II) and mercury(II) complexes with monomethylsubstituted dithiocarbamates as ligands has been synthesized and studied. Their structures are discussed in relation to their spectroscopic, magnetic and thermal properties. The dithio-ligands exhibit bidentate behaviour acting as S,Sdonors in all the complexes. In the far i.r. region particular attention is paid to a comparison of the spectra of the octahedral complexes with those of the other metal derivatives (12 metal to ligand molar ratio). The e.s.r. spectra are indicative of aD _2h symmetry in the cobalt(II) complexes.     

Chemical microscopy of platinum metals and gold: Reactions with 4,4′-dipyridyldihydrochloride

Summary It has been shown that an acid solution of 4,4-dipyridyldihydrochloride can serve to identify low concentrations of most of the platinum metals and gold in 1-N hydrochloric acid solutions of their chlorides by the separation of characteristic micro crystalline precipitates. The reagent was most effective for palladium(II) and platinum(IV), which could be identified in a 20-l drop of sample containing less than 0.6g of metal. Under the conditions imposed, rhodium (III) was the only platinum metal which failed to yield a precipitate. By contrast, under similar conditions 2,2-dipyridyl failed to yield a crystalline precipitate with rhodium(III), ruthenium (III), and iridium(III). Cupric ion caused the separation of a crystalline complex with 4,4-dipyridyl reagent only at a relatively high metal concentration.

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Zusammenfassung Eine saure Lösung von 4,4-Dipyridyldihydrochlorid eignet sich zum Nachweis geringer Konzentrationen der meisten Platinmetalle und des Goldes in 1-n salzsauren Lösungen ihrer Chloride durch charakteristische Mikrokristallfällungen. Am wirksamsten ist das Reagens gegenüber Pd(II) bzw. Pt(IV), von denen sich weniger als 0,6g in einem 20-l-Tropfen nachweisen lassen. Unter den angegebenen Bedingungen gibt Rh(III) als einziges Platinmetall keinen Niederschlag. Dagegen gibt 2,2-Dipyridyl unter diesen Bedingungen außer mit Rh(III) auch mit Ru(II) und Ir(III) keine kristalline Fällung. Kupfer(II)-ionen bilden mit 4,4-Dipyridyl erst in relativ hoher Konzentration eine kristallisierte Komplexverbindung.

     

EPR spectra and characteristics of metal-ligand bond in complexes of divalent copper with some amino acids

Electron paramagnetic resonance spectra were obtained in low-temperature glasses for a series of copper complexes with amino acids: glycine, - and -alanine, valine, leucine, histidine, serine. The ionicity coefficients ² and ₁ ² of the metal-ligand bond were calculated from the spin Hamiltonian constants and from optical data. The results are compared with the stability of the investigated complexes.     

Substituted dipyridylpyridazine rhodium(III) complexes

3,6-Bis(2-pyridyl)pyridazine derivatives (n-dppn) react with hydrated rhodium(III) chloride and bromide (prepared in situ) to give cis-[Rh(n-dppn)₂Cl₂]PF₆·xH₂O (n = 5, 6, 7, 8) and cis-[Rh(n-dppn)₂Br₂]Br·xH₂O (n = 5, 7) complexes, which have been characterized by elemental analyses, conductivity measurements, i.r., electronic and ¹H- and ¹³C-n.m.r. spectra.     

Metal benzoylpivaloylmethanates. Part III. Manganese(III) and iron(III) chelates

Summary The synthesis and principle properties of several novel tris[1-(4-X-phenyl)-4,4-dimethylpenta-1, 3-dionato]-iron(III) and manganese(III) complexes, where X=MeO, Me, H, F, Cl and NO₂, are described. Magnetic susceptibility measurements in the 4.2–295 K range show a near Curie behaviour and a constant magnetic moment for manganese(III) complexes and for iron complexes, with X=F, Cl or NO₂. Iron complexes with ligands having substituents: X=MeO, Me and H, show weak antiferromagnetic interaction (J=ca.–8 cm^–1 for the two former compounds) and a decrease in magnetic moment with decreasing temperature. In both manganese(III) and iron(III) complexes the diketonate ligand can be easily replaced by chlorine. Equilibrium constants could be evaluated only for substitution of the third diketonate ligand by chloride in the iron complexes on the basis of spectrophotometric measurements. For manganese chelates, the replacement of the second diketonate by chloride is accompanied by reduction of manganese(III) manganese(II) and free organic radical formation is observed.     

4,4′-Bipyridyl complexes of iron: Magnetic,Mössbauer and other spectroscopic studies

Summary 4,4-Bipyridyl (4,4-bipy) complexes of ferrous salts of the Fe(4,4-bipy)_x(anion)_y type (where x or y=1 or 2) and of ferric salts of the Fe(4,4-bipy)_m(anion)_n type (where m=1 or 2 and n=3) have been synthesised. Elemental analyses, i.r. and electronic spectra, magnetic and Mössbauer studies have been performed to characterize the complexes. 4,4-Bipy and some anions are inferred to act as bridging ligands. The magnetic moments, electronic and Mössbauer spectra suggest that the complexes are of high spin type with distorted octahedral structures. The value of the isomer shift and quadrupole splitting are discussed in terms of bonding of the ligand and anions.     

Metal complexes of pyrimidine-derived ligands — Part 6. Bischelates of cobalt(II), nickel(II) and monochelates of copper(II) with 3, 5-dimethyl-1-(4′, 6′-dimethyl-2′-pyrimidyl)pyrazole,a potential antitumour agent

Summary Cobalt(II), nickel(II) and copper(II) complexes of 3, 5-dimethyl-1-(4, 6-dimethyl-2-pyrimidyl)pyrazole (DPymPz) have been synthesized and characterized. Magnetic and electronic spectral features show that both [M(DPymPz)₂X₂]·nH₂O [M=cobalt(II) or nickel(II), X=Cl, Br, I, SCN, NO₃, ClO₄ or BF₄ andn=0 or 2] and [Cu(DPymPz)X₂(H₂O)₂] (X=Cl, Br or SCN) are essentially octahedral species. The i.r. spectra indicate that DPymPz is a neutral bidentate ligand being the pyrazolyl and one pyrimidyl ring nitrogen. The X is bonded to the central metal ion in a majority of the complexes.Part 5: N. Saha and D. Mukherjee,Polyhedron,5, 1317 (1986).     

Coordination Properties of Sterically Stressed Zincporphyrins

Spectrophotometric titration and computer simulation were used to study how the nature of porphyrin and extra ligand affect the formation of extra complexes of zincporphyrins in o-xylene. The compounds under study were zincporphyrins (ZnP) with different substituents and phenyl radicals in meso-positions (zinc-5,15-(p-butyloxyphenyl)-2,8,12,18-tetramethyl-3,7,13,17-tetraethylporphyrin (ZnP¹), zinc-5,15-(p-butyloxyphenyl)-2,8,12,18-tetramethyl-3,7,13,17-tetrabutylporphyrin (ZnP²), zinctetraphenylporphine (ZnP³), and zinc complexes with overlapped porphyrin (ZnP⁴). N-Methylimidazole, imidazole, pyridine, 3,5-dimethylpyrazole, and dimethylformamide were used as extra ligands (L). The strength of Zn–L bonding was found to decrease in extra complexes (L)ZnP in the series of ZnP as follows: ZnP⁴> ZnP¹> ZnP²> ZnP³. It was established that the stability constant (logK _st) for sterically nonstressed complexes (L)ZnP⁴linearly increases with growth in the extra ligand basicity (log ) and is proportional to the shift of the main absorption bands () in the electronic spectra of extra complexes of zinctetraphenylporphine. For spatially distorted (L)ZnP¹, (L)ZnP², and (L)ZnP³, the values of logK _stand log , as well as logK _stand , change symbatically. The geometric structure and energy characteristics of pentacoordinated zincporphyrins were calculated by quantum-chemical methods. Correlations were established between the calculated values of the energy of the interaction of the central metal atom with the extra ligand molecule and the stability of the extra complexes of zincporphyrins.     

Norbornadiene complexes of transition metals

Conclusions Correlations were established between the stereochemistry of 2-(-carbinol)norbornadiene complexes of rhodium and their mass spectra.This study is also communication 30 from the series Mass Spectrometry of Transition Metal- Complexes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2701–2703, December, 1982.     

Synthesis,spectral, redox and antimicrobial activities of Schiff base complexes derived from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one and acetoacetanilide

Novel terdentate neutral complexes of Cu^II, Ni^II, Co^II, Mn^II, Zn^II, Cd^II, Hg^II, VO^II, ZrO^II and UO₂ ^II have been prepared using a Schiff base derived from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one (4-aminoantipyrine) and acetoacetanilide. The structural features of the chelates have been confirmed by microanalytical data, i.r., u.v.–vis., ¹H-n.m.r., e.s.r. and mass spectral techniques. Electronic absorption and i.r. spectra of the complexes indicate an octahedral geometry around the central metal ion, except for the VO^II and ZrO^II complexes which show square pyramidal geometry. The monomeric and neutral nature of the complexes are confirmed from their magnetic susceptibility and low conductance values. The cyclic voltammogram of the copper complex in MeCN at 300 K shows a quasi-reversible peak for the couple Cu^II/Cu^III at Ep_c = 0.47 and Ep_a = 0.61 V versus Ag/AgCl and two irreversible peaks for Cu^II Cu^I and Cu^I Cu⁰ reduction at Ep_c = –0.63 and – 0.89 V respectively. The e.s.r. spectra of copper and vanadyl complexes in DMSO solution at 300 K and 77 K were recorded and their salient features are reported. The molecular orbital coefficients (², ²) were calculated for complexes. The antimicrobial activity of the ligand and its complexes have been extensively studied on microorganisms such as Staphylococcus aureus, Klebsiela pneumoniae, Bacillus subtillis, Escherichia coli, Citrobacter ferundii and Salmonella typhi. Most of the complexes have higher activities than that of the free ligand.     

Thermodynamics of substituted rhodanine II: Binary complexes of Th(IV), UO2(II), Ce(III), and La(III) with 3-benzamidorhodanine and its derivatives

Summary Th(IV), UO₂(II), Ce(III) and La(III) chelates with 3-benzamidorhodanine and its derivatives have been investigated potentiometrically in 0.1M KCl and 20% (v/v) ethanol-water medium. The stability of the formed complexes increases in the order Th(IV)>UO₂(II)>Ce(III)>La(III). For the same metal ion, the stability of the chelates is found to increase with decreasing temperature, ionic strength, dielectric constant of the medium and by increasing the electron repelling property of the substituent. The thermodynamic parameters (G, H and S) for complexation are evaluated and discussed. The formation of the complexes has been found to be spontaneous, exothermic and entropically favourable.

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Thermodynamik von substituiertem Rhodanin II: Binäre Komplexe von Th(IV), UO₂(II), Ce(III) und La(III) mit 3-Benzamidorhodanin und seinen Derivaten

Zusammenfassung Th(IV)-, UO₂(II)-, Ce(III)- und La(III)-Chelate mit 3-Benzamidorhodanin und seinen Derivaten wurden in 0.1M KCl und 20% (/) Ethanol-Wasser potentiometrisch untersucht. Die Stabilität der gebildeten Komplexe steigt in der Reihenfolge Th(IV)>UO₂(II)>Ce(III)>La(III). Für ein- und dasselbe Metallion steigt die Stabilität der Chelate mit sinkender Temperatur, Ionenstärke und Dielektrizitätskonstante des Mediums und mit steigender Elektronenabstoßungsfähigkeit des Substituenten. Die thermodynamischen Parameter (G, H und S) für die Komplexbildungsreaktion werden bestimmt und diskutiert. Die Bildung der Komplexe erweist sich als spontan, exotherm und entropisch begünstigt.

     

Solvent extraction of rhodium,ruthenium, and iridium with HDEHP

Solvent extraction of rhodium, ruthenium, and iridium with HDEHP from thioureachloride media was investigated. Under the conditions ([Cl^–]=0.50 M, [HDEHP]=1.0M, [SC(NH₂)₂]=0.50M, pH=4.50, phase contact time 1 min), Rh(III) is extracted 88.3%, Ru(III) and Ir(III) 40.8% and 28.5% respectively at phase ratio 11. The formation of rhodium-thiourea complexes in aqueous solutions, even at 5M chloride concentration, with the possible composition Rh[SC (NH₂)₂]₆ ³⁺ is confirmed by the observed molar ratio of thiourea to rhodium and UV-spectra.     

Tris(2,2,2-trichloroethoxy)iron(III) complexes

Summary The preparation, magnetic moments, i.r., reflectance and⁵⁷Fe Mössbauer spectra of adducts of tris(2,2,2-trichloroethoxy)iron (III) complexes are reported. An alkoxybridged structure is supported by i.r. spectra.⁵⁷Fe Mössbauer spectra are explained in terms of two inequivalent sites in highspin iron(III) octahedral symmetry.Abbreviations Pic-O -picolineN-oxide - Ur urea - DMU N,N-dimethylurea - Suc succinimide - Diox dioxan - Bipy 2,2-bipyridine - Phen 1,10-phenanthroline     

Synthesis and Characterization of Chromium(III), Molybdenum(III), Ruthenium(III) and Osmium(III) Complexes with N2O2–Schiff Bases of 2-Hydroxy-1-Naphthaldimines

Monomolybdenum, monochromium, triosmium and triruthenium clusters, containing weakly coordinated ligands, are valuable starting materials for the preparation of a wide variety of compounds because of the ease with which these ligands can be displaced by another substrate under mild conditions. Four widely used complexes of this type are Mo(CO)₆, Cr(CO)₆, Os₃(CO)₁₂ and Ru₃(CO)₁₂ respectively. These complexes react with 2-hydroxy-1-naphthaldimines to give octahedral complexes which are characterized by elemental analyses, i.r. and u.v.–vis. spectra, molar conductances, d.t.a. and t.g.a. analyses, cyclic voltammetry, magnetic and e.s.r. measurements. The molar conductances in DMF solution indicate that the complexes are non-ionic. The i.r. spectra of complexes (3), (7) and (10) show (CO) bands due to bonded CO groups, however complexes (6) and (13) show (CO) bands due to bonded, bridged and terminal CO groups. The g ₁₁-values of the complexes indicate that they have covalent bond character. Also, the electrochemical reduction of the complexes has been discussed.