X-ray structures of trans-dichloro(4-methylpyrimidine) (η1-phenyl)bis(pyridine)rhodium(III) hydrate and trans-dichloro(phenyl)tris(triphenylstibine)rhodium(III) ethylacetate solvate. Molecular orbital analysis of trans-dichloro (4-methylpyrimidine)(η1-phenyl)bis(pyridine)rhodium(III)

The crystal and molecular structure of trans-dichloro(4-methylpyrimidine)(η ¹ -phenyl)cis-bis(pyridine)rhodium(III) water solvate, 1x 0.17H₂ O, and trans-dichloro(η ¹ -phenyl)tris(triphenylstibine)rhodium(III) ethylacetate solvate, 2x CH₃ CO₂ CH₂ CH₃ have been studied via X-ray diffraction from a single crystal at room temperature. The final refinement converged to R1 conventional index of 0.0350 and 0.0361 for the structural analysis of 1x 0.17H₂ O [space group R(-3) and 2x CH₃ CO₂ CH₂ CH₃ P(-1) , respectively. The 4-methylpyrimidine ligand (Pym) is only weakly bound to Rh in 1, as shown by the long Rh-N distance (2.251(4) Å), compared to the Rh N(pyridine) lengths average, 2.066(4) . N-C bond distances involving the N donor average 1.329(6) and 1.345(6) for Pym and pyridine (Py) ligands, respectively. The C N C bond angle on the donor is 114.1(5)° for Pym and average 117.4(4)^° for Py.The structure of the complex molecule of 2x CH₃ CO₂ CH₂ CH₃ has some differences when compared to that of the corresponding acetone solvate previously studied in this laboratory (Cini, R., Giorgi, G. and Pasquini, L., Inor`. Chim. Acta, 1992, 196, 7). The two structures differ mainly by the orientation of the phenyl donor with respect to the Cl-Rh-Cl axis (which is more eclipsed for the ethylacetate solvate) and by the conformation of the SbPh₃ ligands.Density functional calculations at the B3LYP/LANL2DZ level with full geometry optimization were carried out on the free Pym molecule and on some Sc(N ¹ Pym) ^{3 +}and Sc(N ² Pym) ^{3 +} model molecules. The effect of metal coordination consists mainly in enlarging the (Sc)N-C bond distances up to 0.150Å, whereas the C-N(Sc)-C bond angle decreases of 1.9°. Significant changes on other bond lengths and angles relevant to ring atoms of Pym occur upon metal coordination to the nitrogen atom. The metal coordination to N(2) is less favorable than to N(1) of 7.5 kcal for 1:1 species of Sc^{3 +}Extended Hückel calculations showed that HOMO consists mostly of metal-d orbitals with some character of chloride and phenyl and pyrimidine ligands, whereas LUMO is composed of phenyl, pyridine and pyrimidine orbitals. The method well reproduces the Rh-N and Rh-C bonding distances and gives Rh-C dissociation energy 2.38 and 5.48 times that for the Rh-N(Py) and Rh-N(Pym) bonds, respectively.     

Syntheses and characterization of η 5-pentamethylcyclopentadienyl rhodium(III) and iridium(III) complexes containing polypyridyls

Reaction of [(η ⁵-C₅Me₅)M(μ-Cl)Cl]₂ {M?=?Rh (1), Ir (2)} and [(η ⁵-C₅Me₅)MCl₂(DBT)] (DBT?=?dibenzothiophene) {M?=?Rh (3), Ir (4)} with polypyridyl ligands 2,3-bis(2-pyridyl)pyrazine (bpp), 2,3-bis(2-pyridyl)quinoxaline (bpq), 1,3,5-tris(2-pyridyl)-2,4,6-triazine (tptz), 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz) and 4′-pyridyl-2,2′:6′,2′′-terpyridine (py-terpy) results in the formation of mononuclear cationic complexes, [(η ⁵-C₅Me₅)MCl(poly-py)]⁺ (poly-py?=?polypyridyl ligand). The complexes were isolated as hexafluorophosphate salts and characterized by IR and NMR spectroscopy.     

Properties of η-pentamethylcyclopentadienyl rhodium(III) and iridium(III) complexes with quinolin-8-ol and their cytostatic activity

Reaction of dimers [M(η⁵-C₅Me₅)Cl₂]₂ (M-Rh, Ir) with quinolin-8-ol in molar ratio 1:2 leads to formation of monomer complexes [Rh(η⁵-C₅Me₅)Cl(qol)] (1) and [Ir(η⁵-C₅Me₅)Cl(qol)] (2) (qol = quinolin-8-olate). Compounds 1 and 2 have been characterized with elemental analysis and spectroscopic methods. ¹H NMR spectra revealed that quinolin-8-olate is coordinated via oxygen and nitrogen atoms. The ¹H NMR and ¹³C NMR spectra showed that carbon and hydrogen atoms of pentamethylcyclopentadienyl ligand are equivalent. The structure of rhodium complex has been calculated using DFT B3LYP method. The calculated geometry of complex 1 agrees very well with data found for rhodium complexes containing Cl, C₅Me₅ and qol ligands. Both complexes are active antitumor and antibacterial agents.     

Tetraaquatetrakis(ɛ-caprolactam)lutetium(III) hexaisothiocyanatochromate(III) sesquihydrate

The ionic complex [Lu(?-C₆H₁₁NO)₄(H₂O)₄][Cr(NCS)₆] · 1.5H₂O, the first example of coordination of ?-caprolactam to the lutetium atom, was synthesized by the reaction of Lu(NO₃)₃, K₃[Cr(NCS)₆], and ?-caprolactam in an aqueous solution. The structure of the complex was established by IR spectroscopy and X-ray crystallography. The crystals are triclinic, space group P \(\bar 1\) T = 100 K, a = 11.9604(3) Å, b = 12.3640(3) Å, c = 18.3506(5) Å, α = 91.3200(10)°, β = 108.6640(10)°, γ = 112.4460(10)°, V = 2343.45(10) ų, Z = 2, ρ_calcd = 1.597 g/cm³, R = 0.0299 for 9839 reflections with F _hkl ≥4σ(F). The coordination polyhedron of the lutetium atom is a distorted square antiprism with broken square faces with the oxygen atoms of the organic ligands and water at the vertices. There are weak intramolecular hydrogen bonds N-H…O(H₂) in the cation. The coordination polyhedron of the chromium atom is a somewhat distorted octahedron. The thermal stability of the compound was studied in an inert atmosphere and in air.     

氯冉酸阴离子桥联的Nd(III)-Nd(III), Dy(III)-Dy(III)和 Ho(III)-Ho(III)双 核配合物的合成与磁性

本文合成了三个以氯冉酸阴离子为桥基的稀土双核配合物,Ln~2(Phen)~4(CA)(NCS)~4(Ln=Nd,Dy,Ho;Phen=菲咯啉;CA=氯冉酸二价阴离子)。通过元素分析,红外光谱,电导,电子吸收光谱及变温(4-300K)磁化率表征了配合物,并由变温磁化率观察到的数据和理论方程通过最小二乘法拟合,得出分子内稀土离子间的相互作用参数:Z'J'=-0.79(Nd),-0.67(Dy),-0.63cm^-^1(Ho);表明稀土离子间存在极弱的反铁磁性交换相互作用。零场分裂参数Δ=-0.16(Nd),-0.76(Dy),-2.55cm^-^1(Ho);g=0.618(Nd),1.739(Dy),1.601(Ho),拟合因子≈10^-^4。     

氯冉酸阴离子桥联的Nd(III)-Nd(III), Dy(III)-Dy(III)和 Ho(III)-Ho(III)双 核配合物的合成与磁性

本文合成了三个以氯冉酸阴离子为桥基的稀土双核配合物,Ln~2(Phen)~4(CA)(NCS)~4(Ln=Nd,Dy,Ho;Phen=菲咯啉;CA=氯冉酸二价阴离子)。通过元素分析,红外光谱,电导,电子吸收光谱及变温(4-300K)磁化率表征了配合物,并由变温磁化率观察到的数据和理论方程通过最小二乘法拟合,得出分子内稀土离子间的相互作用参数:Z'J'=-0.79(Nd),-0.67(Dy),-0.63cm^-^1(Ho);表明稀土离子间存在极弱的反铁磁性交换相互作用。零场分裂参数Δ=-0.16(Nd),-0.76(Dy),-2.55cm^-^1(Ho);g=0.618(Nd),1.739(Dy),1.601(Ho),拟合因子≈10^-^4。     

Extraction chromatographic study of aluminium(III) and mutual separation of aluminium(III), gallium(III), indium(III) and thallium(III) with N-n-octylaniline

A selective method has been developed for extraction chromatographic studies of aluminium(III) and its separation from several metal ions with a chromatographic column containing N-n-octylaniline (liquid anion exchanger) coated on silanized silica gel as a stationary phase. The aluminium(III) was quantitatively extracted with the 0.065 mol/L N-n-octylaninine from 0.013 to 0.05 mol/L sodium succinate at a flow rate of 1.0 mL/min. The extracted metal ion has been recovered by eluting with 25.0 mL of 0.05 mol/L hydrochloric acid and estimated spectrophotometrically with aurintricarboxylic acid. The effects of the acid concentration, the reagent concentration, the flow rate and the eluting agents have been investigated. The log-log plots of distribution coefficient (KdAl(III)) versus N-n-octylaniline concentrationin 0.005 and 0.007 mol/L sodium succinate gave theslopes 0.5 and 0.7 respectively and showed theprobable composition of theextracted species was 1:1 (metal to amine ratio) and the nature of extracted species is [RR''NH2+ Al succinate2-] org. .The extraction of aluminium(III) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Aluminium(III) has been separated from multicomponent mixtures, pharmaceutical samples and synthetic mixtures corresponding to alloys. A scheme for mutual separation of aluminium(III), indium(III), gallium(III) and thallium(III) has been developed by using suitable masking agents. The method is fast, accurate and precise.     

FERROMAGNETICALLY COUPLED Gd(III)Cu(II)Gd(III)TRINUCLEAR COMPLEXES

ＦＥＲＲＯＭＡＧＮＥＴＩＣＡＬＬＹ ＣＯＵＰＬＥＤ Ｇｄ（ＩＩＩ）Ｃｕ（ＩＩ）Ｇｄ（ＩＩＩ） ＴＲＩＮＵＣＬＥＡＲ ＣＯＭＰＬＥＸＥＳ￥ＭｉｎｇＭｉｎｇＭＩＡＯ；ＤａｉＺｈｅｎｇＬＩＡＯ；ＺｏｎｅＨｕｉＪＩＡＮＧ；ａｎｄＧｅｎｇＬｉｎＷＡＮＧ（Ｄｅｐ...     

Complexation of Sc(III), Ga(III), In(III) and Ln(III) with Eriochrome Red B

Cyclic linear-sweep voltammetry was used to study the complexation of Sc(III), Ga(III), In(III) and Ln(III) with eriochrome red B (ERB). It was established that all metal ions investigated form complex compounds with azodye having a mole ratio, M(III):ERB = 1:2. The hydroxo forms of M(III) ions, which take part in interaction with ERB, were determined by the Nazarenko method. The stability constants for the formation of these chelates are nearly the same. It was shown that the reduction of the ligand in the complex does not only depend on the peculiarities of complexation, but the processes occurring in pre-electrode layer also influence it.     

Synthesis,Spectra and Crystal Structure of Tetrakis(Triphenylarsine Oxide)Iron(III)-μ-Oxo-Tribromoiron(III) Tetrabromoferrate(III)-Acetonitrile

The oxidation of triphenylarsine with dioxygen in reaction systems containing some iron compound and Br^- anions in acetonitrile leads to the formation of a novel unsymmetrical oxo-bridged diiron(III) complex [(OAsPh₃)₄ Fe(μ-O)FeBr₃]⁺ [FeBr₄]^- ·CH₃CN, where OAsPh₃ is triphenylarsine oxide. The title complex is also formed by direct reaction of iron(III) bromide and OAsPh₃ with dioxygen in acetonitrile solution. The crystal structure of the complex was solved by X-ray diffraction techniques. The cation contains two unsymmetrical species with an Fe-O-Fe bond angle of 159.2(2)°; one iron atom is pentacoordinated by four OAsPh₃ ligands and a γ-oxo ligand which connects the tetracoordinated Fe atom with the FeBr₃O chromophore. Structural parameters and IR spectra of similar complexes are compared and discussed.     

Transport behaviour of the lanthanide 152Eu(III), 153Gd(III) and 170Tm(III) and transplutonium element 254Es(III), 244Cm(III), 241Am(III), 249Cf(III) and 249Bk(III) ions in aqueous solutions at 298 K

Ionic self-diffusion coefficients (D) for trivalent radiotracers, lanthanide and actinide ions have been determined in concentrated aqueous solutions of supporting electrolytes of Gd(NO₃)₃–HNO₃ or Nd(ClO₃)₄–HClO₄ up to 1.5 mol L^?1 at 298.15 K and pH 2.50 by the open-end capillary method. The data obtained in large range of concentrations, allow to derive the limiting value D°, the validity of the Onsager limiting law and a more extended law. This study contributes to demonstrate similarities in transport and structure properties between 4f and 5f trivalent ions explained by a similar electronic configuration, ionic radius and hydration number. An empirical equation is suggested for predicting ionic hydration number with a good precision.     

Can octahedral t2g6 complexes substitute associatively? The case of the isoelectronic ruthenium(II) and rhodium(III) hexaaquaions

For the low-spin t2g6 Ru(OH2)6(2+) (delta V++ = -0.4 cm3 mol-1) and Rh(OH2)6(3+) (delta V++ = -4.2 cm3 mol-1) hexaaquaions, the respective Id and Ia water exchange mechanisms had been assigned, mainly on the basis of activation volumes delta V++ and entering ligands effects for water substitution. For Ru(II) the near-zero delta V++ was supposed to be due to the compensation between a positive contribution (the loss of a water molecule) and a negative one (the contraction of the bonds of the five spectator ligands at the transition state). Recently, it has been suggested that Rh(III), because of its higher positive charge, could promote further spectator ligands bond contraction sufficient to change the sign of delta V++ to a negative value. If true, this would be an example of limitation in the use of delta V++ for a direct diagnosis of the mechanism. Quantum chemical calculations including hydration effects show that the activation energies for the water exchange on Rh(OH2)6(3+) via the Ia (114.8 kJ mol-1) and the D pathways is 21.8 kJ mol-1 in favor of the former. In the case of Ru(OH2)6(2+) all attemps to compute a transition state for an interchange mechanism failed, but the calculated delta E++ for the D mechanism (71.9 kJ mol-1) is close to both experimental delta G298++ and delta H298++ values. The calculated delta sigma d(M-O) values of -0.53 A for rhodium(III) and +1.25 A for ruthenium(II) agree with the experimented delta V++ values and suggest Ia and D (or Id) mechanisms, respectively. In the case of Ru(OH2)6(2+) the shortening of the bonds of the five spectator ligands to reach the transition states corresponds to a volume change of -1.7 cm3 mol-1. For Rh(OH2)6(3+) these spectator ligands' volume decrease is much smaller (maximum of -0.8 cm3 mol-1) and the bond lengths of the two exchanging ligands at the transition state are characteristic of an interchange pathway with a small "a" character. Because of the strong RhIII-O bonds, water exchange on Rh(OH2)6(3+) proceeds via the Ia pathway with retention of the configuration, whereas the same reaction of Ru(OH2)6(2+), which has considerably weaker RuII-O bonds, follows the Id or the D mechanism.     

Formation of an η1-ylidic enamine complex of rhodium(III) during use of triethylamine for a base-promoted reaction

Reaction of triethylamine with mer-RhCl₃(dmso)₃ leads to dehydrogenation of an alkyl group of the amine, and formation of isomers of the ylid complex RhCl₃(dmso)₂(η¹-CH₂CHNEt₂), with accompanying production of equivalent amounts of rhodium(I) species.     

Syntheses of (imidazole)pentaamminemetal(III) and μ-imidazolatodecaamminedimetal(III) complexes from trifluoromethanesulfonato precursors

The [M(NH₃)₅(imidH)]³⁺ complex ions (M = Co, Rh or Ir; imidH = imidazole) can be readily prepared by reaction of [M(NH₃)₅(OSO₂CF₃)]²⁺ ions with imidazole in sulfolane. Subsequent reaction of [M′(NH₃)₅(OSO₂CF₃)]²⁺ with [M(NH₃)₅(imidH)]³⁺ in sulfolane in the presence of a non-coordinating base permits synthesis of the binuclear imidazolate-bridged complexes [(NH₃)₅M(imid)M′(NH₃)₅]⁵⁺ (M = M′= Co or Rh; M = Co, M′ = Rh), characterized by spectroscopic, chromatographic and voltammetric methods, and by reactivity.     

Octa(ɛ-caprolactam)erbium(III) hex(isothiocyanato)chromate(III): Synthesis and crystal structure

The ionic mixed-ligand bimetallic complex [Er(?-C₆H₁₁NO)₈][Cr(NCS)₆] has been synthesized and studied by X-ray diffraction analysis. The crystals are monoclinic, space group C2/c, a = 39.627(2) Å, b = 22.3406(11) Å, c = 23.7155(10) Å, β = 107.687(2)°, V = 20 002.9(16) ų, Z = 12, ρ_calcd = 1.467 g/cm³. The coordination polyhedron of the erbium atom is a distorted square antiprism formed by the oxygen atoms of the organic ligands. The Er-O bond lengths vary within 2.29–2.44 Å. The coordination polyhedron of the chromium atom is a slightly distorted octahedron, and the Cr-N bond lengths range from 1.99 to 2.01 Å.     

Polynuclear Heteroligand Yb(III)–Er(III) Complexes as Potential Upconversion Materials

Russian Journal of Coordination Chemistry - The synthesis of complexes LnI(C6F5O)2 and LnCp(L)2 (Ln = Er, Yb; L = C6F5O, SONF), which are convenient precursors for the preparation of heteroligand...     

Mit Cer(III)-Sulfatl?sungen lassen sich Hexacyanoferrat(III) und Permanganat

Ohne Zusammenfassung     

Thermal analysis of rare-earth metal(III) hexa(isothiocyanato)chromate(III) complexes with ɛ-caprolactam

Thermal decomposition of the complexes [LnL₈][Cr(NCS)₆] (Ln = La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb³⁺, Lu³⁺; L = ɛ-C₆H₁₁NO) in air and in inert atmosphere was studied by thermogravimetry, X-ray phase analysis, IR spectroscopy, and mass spectrometry. The compositions of gaseous and solid thermolysis products were established. A reversible thermochromic effect was found on heating to 200–210°C.     

Ferrocene-containing ligands in the self-assembly of trinuclear μ3-oxocentered carboxylate complexes of chromium(III, III, III)carboxylate complexes of chromium(III, III, III)

New trinuclear μ₃-oxocentered chromium(III, III, III) complexes were obtained by the self-assembly of ferrocenecarboxylate ligands and the Cr₃O fragment. The complexes were investigated by fast-atom bombardment (FAB) mass spectrometry, cyclic voltammetry, and electronic and IR spectroscopy. V. I. Vernadskii Institute of General and Inorganic Chemistry, National Academy of Sciences of Ukraine, 32/34 Prospekt Akademika Vernadskogo, Kiev 03142, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 4, pp. 233–237, July–August, 2000.     

Mechanism of rhodium(III)-catalyzed formal C(sp3)H activation/spiroannulation of α-arylidene pyrazolones with alkynes: A computational study

DFT calculations were performed to investigate the rhodium-catalyzed formal C(sp³)-H activation/ spiroannulation of α-arylidene pyrazolones with alkynes. The calculations indicate that the spiroannulation through the proposed C-C reductive elimination is kinetically unfeasible. Instead, the C-C coupling from the eight-membered rhodacycle was proposed to account for the experimental results