Polyurethane foam for the extraction of rhodium and its separation from iridium

The rate of reaction of rhodium with thiocyanate at 90 degrees in the presence of lithium chloride or sufficient hydrochloric acid and the subsequent extraction of the metal from hydrochloric acid medium by polyether-type polyurethane foam was investigated. The effect of the chloride salts of different cations decreased in the order Li(+) > Na(+) > K(+) indicating that Rh(SCN)(6)(3-) is extracted through a simple solvent-extraction mechanism rather than the "cation-chelation" mechanism. The separation of rhodium and iridium was also examined and the results indicated that in the presence of 5-fold excess of iridium, an average of 95 +/- 2% iridium remained in the aqueous phase while an average of 93 +/- 2% rhodium was retained by the foam.     

The extraction and determination of thiocyanate complexes by use of polyurethane foam

Metal thiocyanate solutions were extracted with polyether-type polyurethane foam and the metal contents determined by X-ray fluorescence. Iron, cobalt and zinc were extracted individually and collectively from 3.0M NH(4)Cl and 1.0M NH(4)SCN solutions. Similarly platinum and palladium could be simultaneously extracted from 0.12MNH(4)SCN and 5.0MNH(4)Cl for subsequent determination. The metal extractions were more than 95% complete and the determination of one metal was not affected by the presence of the others.     

Low-valent molecular plutonium halide complexes

Treatment of plutonium metal with 1.5 equiv of bromine in tetrahydrofuran (thf) led to isolation of PuBr3(thf)4 (1), which is a new versatile synthon for exploration of non-aqueous Pu(III) chemistry. Adventitious water in the system resulted in structural characterization of the eight-coordinate complex [PuBr2(H2O)6][Br] (2). The crystal structure of PuI3(thf)4 (3) has been determined for the first time and is isostructural with UI3(thf)4. Attempts to form a bis(imido) plutonyl(VI) moiety ([Pu(NR)2](2+)) by oxidation of PuI3(py)4 with iodine and (t)BuNH2 resulted in crystallization of the Pu(III) complex [PuI2(thf)4(py)][I3] (4). Dissolution of a Pu(IV) carbonate with a HCl/Et2O solution in thf gave the mixed valent (III/IV) complex salt [PuCl2(thf)5][PuCl5(thf)] (5) as the only tractable product. Oxidation of Pu[N(SiMe3)2]3 with TeCl4 afforded the Pu(IV) complex Pu[N(SiMe3)2]3Cl (6), which may prove to be a useful entry route for investigation of organometallic/non-aqueous tetravalent plutonium chemistry.     

Heterobimetallic rhodium-gold halide and hydride complexes

Heterobimetallic Rh(I)Au(I) halide complexes react with LiHBEt(3) to afford the corresponding hydride, and they are oxidised by halogen to afford thermally stable Rh(II)Au(II) complexes. The hydride complex reacts with acid and halogen sources to produce H(2) and HCl, respectively. The Rh(II)Au(II) complexes exhibit optical and photochemical properties that are derived from the bimetallic core.     

Facile halide replacement in electron rich complexes

Reactions of MnL₅X or Mn(CO)L₄X compounds (L = several aryl isocyanides, X = halide) with AgPF₆ give [MnL₆]PF₆ or [Mn(CO)L₅]PF₆ respectively. These reactions are presumed to occur with initial halide extraction to give an intermediate solvated species [MnL₅solv]⁺ or [Mn(CO)L₄solv]⁺ which can subsequently decompose or scavenge free L from solution to give the products observed. Addition of an alternative potential ligand L′ allows preparation of mixed ligand species [MnL₅L′]PF₆ or [Mn(CO)L₄L'‵PF₆ (L = MeNC, ^tBuNC, py). Cyclic voltammetric studies on the various complexes have been carried out, and results correlated with infrared data and with theory.     

Cobalt(II) halide complexes with ethyleneselenourea

The complexes obtained from ethyleneselenourea and cobalt(II) halides have been prepared and characterized. They have formula CoL₂X₂ (X = Cl, Br, I), tetrahedral stereochemistry and they are Se-bonded to the cobalt(II). They are comparatively studied with the previously reported complexes of cobalt(II) with ethylenethiourea, by IR and visible spectroscopy and magnetic susceptibilities. Using the average linand field approximation, the ethyleneselenourea is located at the very low end of the nephelauxetic series.     

Self-assembly of square-planar halide complexes of phosphine-stabilised stibenium salts

Chloride and bromide ions direct the self-assembly of supramolecular square-planar halide complexes in which four trimethylphosphine-stabilised diphenylstibenium ions surround the central halide ion in discrete centrosymmetrical structures of C(4h) symmetry.     

Structural diversity of yttrium(III) halide complexes

X-ray crystallographic data on yttrium(III) compounds containing halide (pseudohalide) ligands in the coordination sphere have been summarized and systematized. Trends in the change in the coordination number (CN) and the coordination polyhedron geometry, as well as specific features of the central ion environment in monomeric, dimeric, and polymeric complexes, have been considered. 139 references.     

Vibrational spectra of zinc halide complexes with trimethylphosphine oxide

The Raman and IR spectra are reported for the complexes ZnCl₂.2TMPO, ZnBr₂.2TMPO and ZnI₂.2TMPO. The observed frequencies for polycrystalline samples are assigned on the basis of a C_3v structure for the TMPO ligand and a C_2y structure for the ZnX₂O₂ skeletal fundamentals. To discuss the coordination effects of TMPO, the ligand vibrations are compared with those of free TMPO and the skeletal vibrations with those of acetonitrile complexes. Using the ratios of G matrix elements and of observed frequencies for symmetric and asymmetric Zn-X stretching modes, the ZnX₂O₂ skeletal structures are found to be tetrahedral.     

Luminescence of antimony(III) halide complexes with aniline

The antimony(III) chloride and bromide complexes with aniline, (C₆H₅NH₃)₂SbCl₅·(C₆H₅NH₃)Cl·H₂O (I) and (C₆H₅NH₃)₂SbBr₅ (II), were synthesized, and their spectral luminescence properties were studied. An interesting peculiarity of I and II is the possibility of selective excitation of luminescence in the π system of the (C₆H₅NH₃)⁺ outer sphere anilinium cation and intrinsic luminescence of the s ² ion. The population scheme for the luminescent antimony ³ P ₁ level in I and II is discussed using the luminescence, UV, and photoelectron spectroscopy data. Original Russian Text ? T.V. Sedakova, A.G. Mirochnik, V.E. Karasev, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 2, pp. 380–382.     

Synthesis of catalytically active diene and cyclopentadienyl rhodium halide complexes

1. Download : Download high-res image (96KB)
2. Download : Download full-size image

     

Vibrational assignments of crystalline waters in some uranyl halide complexes

To establish the vibrational assignments of the bands near 450 and 320 cm⁻¹ in the hydrated uranyl halide complexes, M₂UO₂X₄·nH₂O (M = Na, K, Rb, Cs, NH₄; X = Cl, Br)m, their IR spectra have been measured in the region from 500 to 200 cm⁻¹ and investigated in some detail by making use of deuteration effect. The results show that the former band is evidently assigned to water libration (wagging vibration) and the latter to MO stretching vibration. Some possible structure of water coordination in the hydrated complexes is estimated on the basis of the spectral results.     

C-H activation of ethers and alkanes by germylene-aryl halide complexes

Regioselective, room-temperature C-H activation of alkanes and ethers by stable germylenes and aryl halides is reported. Germylenes, Ge[CH(SiMe3)2]2 and Ge[N(SiMe3)2]2, and aryl halides, PhI, PhBr, and PhCl, have been employed. High yields of C-H activation products can be obtained through the use of high-dilution techniques.     

Thermal studies of zinc and cadmium halide complexes with N-tert-alkylacrylamides

The thermal properties of complexes of N-tert-butylacrylamide and N-tert-amylacrylamide with ZnCl₂, ZnBr₂, CdCl₂ and CdBr₂ have been studied in air and in argon by TG and DTA. The decomposition proceeds in two steps with evolution of simple, low molecular weight gaseous products. The use of various heating rates revealed an additional exothermic DTA peak for complexes with zinc and cadmium chlorides corresponding to a solid state polymerization reaction which was confirmed by IR spectral analysis. This effect was not observed for corresponding complexes of zinc and cadmium bromides, which show much lower thermal stability.

---

Zusammenfassung Die thermischen Eigenschaften der Komplexe von N-Tertbutylacrylamid und N-Tertamylacrylamid mit ZnCl₂, ZnBr₂, CdCl₂ und CdBr₂ wurden in Luft und in Argon durch TG und DTA studiert. Die Zersetzung verläuft in zwei Stufen unter Entwicklung einfacher gasförmiger Produkte niedriges Molekulargewichts. Der Einsatz verschiedener Aufheizgeschwindigkeiten zeigte für Komplexe mit Zink- und Cadmiumchloriden einen zusätzlichen DTA Peak, der Festphasen-Polymerisationsreaktion entsprechend, welche durch IR-Spektralanalyse bestätigt wurde. Dieser Effekt wurde bei den entsprechenden Komplexen der Zink- und Cadmiumbromide, welche eine viel geringere Thermostabilität besitzen, nicht beobachtet.

---

Résumé On a étudié, par TG et ATD, dans l'air et l'argon, les propriétés thermiques des complexes du N-tertbutyl-acrylamide et du N-tétramylacrylamide avec ZnCl₂, ZnBr₂, CdCl₂ et CdBr₂. La décomposition s'effectue en deux étapes, avec dégagement de produits gazeux simples de faible poids moléculaire. L'application de différentes vitesses de chauffage a révélé, pour les complexes des chlorures de zinc et de cadmium, un pic exothermique additionnel en ATD qui correspond à la réaction de polymérisation dans l'état solide et qui a été confirmé par spectrométrie infrarouge. On n'a pas observé cet effet dans le cas des complexes correspondants des bromures de zinc et cadmium dont la stabilité thermique est bien plus faible.

---

N- - N- ZnCl₂, ZnBr₂, CdCl₂ CdBr₂. , . . , . , .

     

Alkyl halide charge transfer complexes with hard Lewis bases

The unusual charge transfer complexes formed between alkyl halide acceptors and hard Lewis base donors (amines and alcohols) in low dielectric solvent were examined using ultraviolet spectroscopy. The lambda(max) of the complex decreases with increasing ionization potential of the donor. The complex formation equilibria were probed by thermodynamic analysis and concentration variation. At ambient temperatures complex formation is generally slightly exergonic with a negative complexation entropy. The complex extinction coefficients are much lower (<10 l mol(-1) cm(-1)) than for typical charge transfer complexes. These complexes are extraordinary within a classical context since the halide acceptors have a negative electron affinity. They exhibited an atypical hypsochromic shift with increasing solvent dielectric constant.     

Nicke(II) halide complexes with hypoxanthine and xanthine

Summary Ni(LH)₃LX complexes (LH=hypoxanthine or xanthine; X=Cl, Br or I) are formed by boiling under reflux 2:1 molar mixtures of LH and hydrated NiX₂ in HC(OEt)₃–MeCO₂Et. The new complexes appear to be linear chain-like polymers, characterized by bidentate monoanionic L^– ligands singly bidging between adjacent Ni²⁺ ions. A coordination number six is attained by the presence of three terminal unidentate LH and one X ligand in the first coordination sphere of each Ni²⁺ ion. The neutral LH and monoanionic L^– ligands bind exclusivelyvia ring nitrogens to Ni^II. The probable binding sites of the uni- and bi-dentate hypoxanthine and ligands in the new complexes are discussed.Presented in part at the 3rd Chem. Congress of North America (LH=xanthine) and the XXVI ICCC (LH=hypoxanthine), see refs. 1 and 2, respectively.     

Platinum(II) halide complexes with propan-1-amine

Summary The complexescis-[PtPra₂X₂],trans-[PtPra₂X₂], [PtPra₃X]X, [PtPra₄]X₂ and [PtPra₄]X₂ · 2H₂O, where Pra= propan-1-amine and X=Cl or Br, have been prepared with good yields and characterized by thermal analysis and i.r. and¹H n.m.r. spectroscopy. The best methods to obtain the pure products are discussed. The TG and DTA data are reported for all the complexes; in particular the thermal degradation of the 13 and 14 bromo-derivatives allows to isolate the intermediatetrans-[PtPra₂Br₂]. The i.r. spectra are characteristic of geometry and stoichiometry, as the¹H n.m.r. spectra ofcis-[PtAm₂Br₂],trans-[PtAm₂Br₂], [PtAm₃Br]Br and [PtAm₄]Br₂ (Am=propan-1-amine or hexan-1-amine) in deuteriated benzene, acetone and chloroform.     

One-hydrogen polarization in hydroformylation promoted by platinum-tin and iridium carbonyl complexes: a new type of parahydrogen-induced effect

The first use of parahydrogen-induced polarization (PHIP) in hydroformylation is described including a novel one-hydrogen polarization (oneH-PHIP) in the product RCHO proton. Observed in propanal formed in the reaction of trans-PtCl(COEt)(PPh3)2 + SnCl2 under parahydrogen, oneH-PHIP was examined using the model hydroformylation catalyst Ir(COEt)(CO)2(dppe) (dppe = bis(diphenylphosphino)ethane) that yields the characterized acyl dihydride IrH2(COEt)(CO)(dppe). It is found that oneH-PHIP occurs as a consequence of second-order effects in the acyl dihydride species coupled with stereospecific reductive elimination of aldehyde. Thus, even though hydrogen transfer to substrate in hydroformylation is nonpairwise, parahydrogen effects prove useful mechanistically.