Carbonyl complexes of rhodium(I) and rhodium(III) with 2,2′-biquinoline

Novel carbonyl complexes of rhodium(I) and rhodium(III) containing the bidenate nitrogen donor ligand 2,2′-biquinoline (biq) have been prepared; they are of the types RhX(CO)₂ biq and RhX(CO)biq (X = Cl, Br, I). Cationic carbonyl and substituted carbonyl complexes of the types [Rh(CO)₂biq]ClO₄ and [Rh(CO)biqL₂]ClO₄, where L is tertiary phosphine or arsine have also been isolated. In spite of considerable steric crowding around the nitrogen atoms, 2,2′-biquinoline behaves much like 2,2′-bipyridine in forming carbonyl complexes of rhodium.     

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.     

Iridium (III) and rhodium (III) triazoles by 1,3-dipolar cycloadditons to a coordinated azide in iridium (III) and rhodium (III) compounds

The reaction of [(η⁵-C₅Me₅)M(μCl)Cl]₂ with the ligand (L^∩L) in the presence of sodium methoxide yielded compounds of general formula [(η⁵-C₅Me₅)M(L^∩L)Cl] (1–10) (where M = Ir or Rh and L^∩L = N^∩O or O^∩O chelate ligands). Azido complexes of formulation [(η⁵-C₅Me₅)M(L^∩L)N₃] (11–20) have been prepared by the reaction of [(η⁵-C₅Me₅)M(μN₃)(X)]₂ (X = Cl or N₃) with the corresponding ligands or by the direct reaction of [(η⁵-C₅Me₅)M(L^∩L)Cl] with NaN₃. These azido complexes [(η⁵-C₅Me₅)M(L^∩L)N₃] undergo 1,3-dipolar cycloaddition reaction with substituted alkynes in CH₂Cl₂ and for the first time in ethanol at room temperature to yield iridium (III) and rhodium (III) triazoles (21–28). The compounds were characterized on the basis of spectroscopic data, and the molecular structures of 2 and 26 have been established by single crystal X-ray diffraction.     

Metal chelates of heterocyclic nitrogen-containing ketones,Part XXII. Spectroscopic studies on rhodium(III) complexes of phenyl-2-picolylketone-2-pyridyl hydrazone

Summary Mono, bis and tris complexes of rhodium(III) with phenyl-2-picolylketone-2-pyridyl hydrazone (PPKPyH) have been characterized. In every case, the imino-proton of PPKPyH shows marked acidity associated with the coordination to rhodium(III). Electronic spectra show that all complexes are octahedral. The B-values suggest a strong covalency in the metal-ligand -bond and the Dq-values indicate a medium-strong ligand field. The magnetic susceptibility indicates that PPKPyH forms low-spin complexes with rhodium(III).¹H n.m.r. spectra show that the tris(ligand) complexes arecis isomers. I.r. spectra show that the ligand is neutral or monobasic tridentate or bidentate. Far i.r. studies show that [Rh(PPKPyH)X₃] · 2 H₂O (X = Cl, Br or I) aremer isomers. The effect of pH variation on the rection products is also discussed.     

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.     

Lanthanum(III) and prasedymium(III) complexes with piperazine dithiosemicarbazones

Lanthanum(III) and praseodymium(III) complexes of the type [Ln(L)Cl(H₂O)]₂ (Ln = La(III) or Pr(III); LH₂ = dithiosemicarbazone ligands derived from piperazine dithiosemicarbazide and benzaldehyde, 4-nitrobenzaldehyde, and 2-methoxybenzaldehyde) have been synthesized in methanol in the presence of sodium hydroxide. The complexes have been characterized by elemental analyses, molecular weight, molar conductance, electronic absorption, IR, and ¹H and ¹³C NMR spectral studies. Nephelauxetic ratio, covalency parameter, and bonding parameter for these complexes have also been calculated. Thermal studies of the complexes have been carried out using TG, DTG, and DSC techniques. Kinetic parameters, such as apparent activation energy and order of reaction, were determined by the Coats-Redfern graphical method. The heats of reaction for different reaction steps were calculated from DSC curves. The article was submitted by the authors in English.     

Theoretical studies on the complexation of Eu(III) and Am(III) with HDEHP: structure,bonding nature and stability

Separation of trivalent lanthanides (Ln(III)) and actinides (An(III)) is a key issue in the advanced spent nuclear fuel reprocessing. In the well-known trivalent actinide lanthanide separation by phosphorus reagent extraction from aqueous komplexes (TALSPEAK) process, the organophosphorus ligand HDEHP (di-(2-ethylhexyl) phosphoric acid) has been used as an efficient reagent for the partitioning of Ln(III) from An(III) with the combination of a holdback reagent in aqueous lactate buffer solution. In this work, the structural and electronic properties of Eu³⁺ and Am³⁺ complexes with HDEHP in nitric acid solution have been systematically explored by using scalar-relativistic density functional theory (DFT). It was found that HDEHP can coordinate with M(III) (M=Eu, Am) cations in the form of hydrogen-bonded dimers HL₂^- (L=DEHP), and the metal ions prefer to coordinate with the phosphoryl oxygen atom of the ligand. For all the extraction complexes, the metal-ligand bonds are mainly ionic in nature. Although Eu(III) complexes have higher interaction energies, the HL₂^- dimer shows comparable affinity for Eu(III) and Am(III) according to thermodynamic analysis, which may be attributed to the higher stabilities of Eu(III) nonahydrate. It is expected that this work could provide insightful information on the complexation of An(III) and Ln(III) with HDEHP at the molecular level.     

Rhodium(III), palladium(II), and platinum(II) complexes with 2-(2-hydroxybenzoyl)-N-methylhydrazinecarbothioamide: Syntheses,structures, and spectral characteristics

The syntheses and spectral (IR, UV-VIS, XPS, and ¹H and ¹³C NMR) characteristics of the rhodium(III), palladium(II), and platinum(II) complexes with 2-(2-hydroxybenzoyl)-N-methylhydrazinecarbothioamide (HBMHCTA) are described. The coordination of HBMHCTA to the central metal ion and its intraligand rearrangement in the complex formation of rhodium(III) ions are studied. The structure of the mixed-ligand complex [Pd(H₂L)PPh₃] is determined by X-ray diffraction analysis.     

Synthesis, spectral, thermal and biological studies of Co(III) and binuclear Ni(II) complexes with a novel amine-imine-oxime ligand

Two different metal complexes of [Co(HL)(L)(Ac)₂]·4H₂O (I) and [Ni₂(L)₂(Ac)₂]·4H₂O (II), have been synthesized with newly prepared amine-imine-oxime ligand [HL = 3-(4′-aminobiphenyl-4-ylimino)-butan-2-one oxime, Ac = CH₃COO⁻]. This ligand HL was prepared by the condensation of diacetylmonoxime with benzidine. The structure of the ligand and complexes have been proposed by elemental analyses, IR, ¹H, and ¹³C NMR, electronic spectra, magnetic susceptibility measurements, mass spectra, molar conductivity and thermo gravimetric analysis. The molar conductance measurements of the complexes in DMF solution correspond to non electrolytic nature for the complexes. Octahedral and tetrahedral geometries have been determined to the complexes of Co(III) and binuclear Ni(II) respectively. The ligand and its metal complexes were tested in vitro for their biological effects. Their activities against two gram-positive (Bacillus subtilis and Staphylococcus aureus) and one fungal specie (Candida albicans) were found. They were inactive against tested gram negative bacteria. The text was submitted by authors in English.     

Mass spectra of partially fluorinated β-diketonato complexes of Al(III), Cr(III), Fe(III) and Co(III)

The mass spectra of the Al(III), Cr(III), Fe(III) and Co(III) complexes of the anions of hexafluoroacetylacetone (hfac) trifluoroacetylacetone (ttac), benzoyltrifluoroacetone (btac) and thenoyltrifluoroacetone (ttac) have been determined and are discussed here. Emphasis is placed on discerning which of the observed reactions may properly be attributed to the influence of the metal in the complex and those which may be thought of as arising from the nature of the ligand. The most important influence of the coordinated metal is related to its ability to be reduced²; however, the presence of the metal serves to prohibit or facilitate certain rearrangement reactions relative to the free protonated ligand. Since essentially all fragmentation occurs within or by loss of a ligand, the nature of the ligand determines the nature of the observed fragments. Where intramolecular com-petition of fragment types is possible (tfac, btac and ttac complexes), the most probable fragment of a given class, odd electron or even electron, is easily determined. The most commonly eliminated fragments are CF₃and CF₂. Certain metastable peaks are associated with consecutive decomposition in the field free region. Such a phenomenon appears to be common for molecules of the type studied here.     

Synthesis of cationic gold(III) complexes using iodine(III)

Abstract

We report the synthesis and characterization of cationic Au(III) complexes supported by nitrogen-based ligands. The syntheses are achieved by reacting Au(I) complexes [Au(N-Me-imidazole)₂]⁺ and [Au(pyridine)(NHC)]⁺ with iodine(III) reagents PhI(OTf)(OAc) and [PhI(pyridine)₂]²⁺ yielding a series of cationic gold(III) complexes. In contrast, reactions of phosphine ligated gold(I) complexes with iodine(III) reagents results in the oxidation of the phosphine ligand.     

Redox properties of cobalt(II) and methylcobalt(III) complexes with dianionic macrocyclic polychelate ligands

Redox potentials of a series of complexes of cobalt(II) and organocobalt(III) with tetraazamacrocyclic (N₄) and N₂O₂-noncyclic polychelate ligands have been determined by cyclic voltammetry. Introduction of ano-phenylene fragment instead of an ethylene fragment into an equatorial ligand and/or exchange of an N₄-coordination chromophore for the N₂O₂-analog has been shown to result in the anodic shift of redox potentials of MeCo(IV)L/ MeCo(III)L, MeCo(III)L/MeCo(II)L, and Co(II)L/Co(I)L pairs. It has been established that the solvent effect on redox potential is larger for Co(III)L/Co(II)L than for other pairs. Apparently, this is the first case when quasi-reversible stages of oxidation of MeCo(III)L to MeCo(IV)L⁺ and MeCo(IV)L⁺ to [MeCo(IV)L]²⁺ can be simultaneously observed. A. relatively stable complex of methylcobalt(IV) with a long lifetime at 20 °C has been registered by the ESR method.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1029–1033, June, 1993.     

31P-Kernresonanzspektrometrische Untersuchungen an Phosphato-Cobalt(III)- und Rhodium(III)-Komplexen

³¹P N.M.R. Spectroscopic Investigations of Phosphato Complexes of Cobalt(III) and Rhodium(III) ³¹P n.m.r. spectra of phosphato complexes of cobalt and rhodium(III) are recorded. The coordination shift of monodentate phosphate is 8–9 ppm, of bidentate phosphate 18 ppm, of phosphite 10–11 ppm, of fluorophosphate 6–7 ppm. Monophosphato and pentaamminaquacobalt complexes condense with the elimination of water to a m?-complex. The ability of the phosphato complexes of cobalt(III) to condense phosphate to diphosphate was investigated. After heating [CoPO₄en₂] · 2 H₂O with an excess of dihydrogenphosphate only small amounts of the expected diphosphate complex could be detected. The analogous reaction with fluorophosphate results in an appreciably higher yield of the diphosphate complex.     

The complexation of rhodium(III) with acyclic diaminedithioether (DADTE) ligands

(103)Rhodium(III) complexes derived from seven acyclic tetradentate N(2)S(2) ligands (one diaminedithiol and six diaminedithioether ligands) have been synthesized and characterized. Structural variations in the ligand include the length of carbon backbone between the coordinating atoms (222; 232; 323; 333), the presence or absence of gem-dimethyl groups α to sulfur, and the nature of the organic moiety on the sulfurs (hydrogen, p-methoxybenzyl and methyl). For each ligand, the formation of cis and/or trans dichloro isomeric complexes was assessed. Two complexes have been further characterized by single crystal X-ray diffraction. Preparation of the (103)Rhodium(III) complexes was conducted and overall radiochemical yields, in vitro stability and log D(7.4) values were measured. From these studies, the ligand with the 232 chain length, gem-dimethyl groups and the methyl thioether (L4) emerged as a preferred ligand for formation of rhodium complexes with trans geometry and highest radiochemical yields.     

Synthesis and photophysicochemical properties of novel mononuclear rhodium(III) phthalocyanines

Chloro axially-substituted octa(4-isopropylphenoxy)rhodium(III)phthalocyanine, (R)₈PcRhCl (3), was reacted with the nitrogenous bases pyridine (Py) and pyrazine (Pyz) to give the axially-disubstituted octa(4-isopropylphenoxy)rhodium(III)phthalocyanines [(R)₈PcRhCl(L)] (4) and (5), L = (Py) and (Pyz), respectively. In this study, the fluorescence quantum yield (Φ_F), the phosphorescence quantum yield (Φ_phos) and the photodegradation quantum yield (Φ_pd) values for the newly synthesized rhodium phthalocyanine complexes (RhPcs) 4 and 5 are reported. The complexes have also been fully characterized by elemental analysis, FD mass spectrometry, FT-IR and ¹H NMR spectroscopy.     

Synthesis,characterization, catalytic and antimicrobial studies of ruthenium(III) complexes

Ru(III) complexes of the type [RuXB(L)2] have been prepared by the reaction of 3,4-dihydropyrimidin-2(1H)-ones/thiones (HL¹–HL⁴) with the precursors of the type [RuX₃B₃] where X=Cl or Br; B=PPh₃ or AsPh₃ and L is the deprotonated ligand. The synthesized complexes were characterized by physico-chemical methods, electrochemical and magnetic moment data. The catalytic efficiency of the complexes were examined in the oxidation of alcohols and antimicrobial studies were also carried out.      

A study on the solution and gas-phase chemistry of Mn(III) and Fe(III) tetraarylporphyrin complexes by fast-atom bombardment mass spectrometry.: 2: Synthesis and characterization of molecular complexes

The chemical behavior of Fe(III) and Mn(III) tetraarylporphorin (TAP) complexes with N-alkylimidazoles and other suitable ligands was studied by direct reaction in the fast-atom bombardment matrix and in the gas phase. The coordination reaction occurs at the metal center and yields molecular adducts of porphyrin/ligand (PL) and PL₂ stoichiometry. Coordinative competition between free and covalently linked ligands can be used to probe the conformation of “tailed” Mn(III)-TAP.     

The Affinity of Gallium(III) and Indium(III) for Nitrogen Donor Ligands

Abstract

Dedicated to Professor Arthur Martell on the occasion of his seventy fifth birthday.

The complexes of In(III) and Ga(III) with a variety of nitrogen donor ligands were studied in aqueous solution by glass electrode potentiometry at 25°C in 0.1 M NaNO₃. The ligands were 2-aminomethylpyri-dine (AMPY), ethylenediamine (EN), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (THPED), and N,N-bis(2-hydroxyethyl)glycine (BICIN). A variety of mixed ligand complexes of the MLOH type were detected with many of the above ligands as L. The logK₁ values obtained were with Ga(III) 8.40 (AMPY), 7.94 (THPED) 12.72 (EN), and In(III) 7.6 (AMPY), 8.20 (THPED), and 7.06 (BICIN). These formation constants are discussed in relation to previous predictions that In(III) and Ga(III) would have a substantial chemistry with nitrogen donor ligands. Of particular interest is the Ga(III) system with EN, where a very stable Ga(EN)³⁺ complex is formed, but no higher complexes except for hydrolyzed species such as Ga(EN)OH²⁺ and Ga(EN)(OH)₂ ⁺.     

Extraction of rhodium(III) with sulfoxides from hydrochloric acid solutions

Extraction of rhodium(III) from hydrochloric acid solutions with dihexyl sulfoxide (DHSO) and with petroleum sulfoxides (PSOs) was studied, and the optimal conditions for its recovery were found. At a phase contact time of up to 0.5 h, the extraction of rhodium(III) with sulfoxides occurred mainly by an ionassociation scenario. If the phase contact time exceeds 0.5 h, a mixed extraction scenario predominated to form the extracted complexes (L · H⁺) · [RhCl₄L₂]-(DHSO)_o and PSO (LH⁺) · [RhCl₄(H₂O) · L]⁻. The protonation of the extraction agents occurred at the donor oxygen atoms of the sulfoxide group. When rhodium was extracted with PSOs, the coordination of the extractant molecule in the inner coordination sphere of the acido complex to the metal ion occurred through the donor sulfur atom of the sulfoxide group, while with the use of DHSO, through the donor atoms of sulfur and oxygen of the sulfoxide group. Electronic, ¹H NMR, and IR spectroscopy and elemental analysis were used to determine the composition of the extracted compounds and suggest their structure.     

Palladium(II), platinum(II), rhodium(III) and iridium(III) complexes coordinated with 2-aryl-4,5-dimethyl-1,2,3-triazoles as bidentate nitrogen-carbon chelate ligands

Summary Cyclometallations of 2-aryl-4,5-dimethyl-1,2,3-triazoles [H(C-N)] occur with palladium(II), platinum(II), rhodium(III) and iridium(III) chloride. Pallaciation and platination form [MCI(C-N)]₂, and rhodation and iridation [MCI(C-N)₂]₂ species. These complexes react with monodentate ligands, L, such as pyridine and tri-n-butylphosphine to give MCl(C-N)L and MCl(C-N)₂ L complexes. Corresponding bromo and iodo complexes are prepared by metathesis with lithium bromide and iodide. Spectroscopic data suggest that MX(C-N)L compounds (X = Cl, Br or I) have a structure withtrans-C,X andtrans-N,L, while [MX(C-N)₂ L] has atrans-N,N,cis-C,C, andcis-X,L structure.Author to whom all correspondence should be directed.