Reaktion von Phosphinboran,Phenylphosphinboran und Phosphoniumjodid mit Natriumtetrahydridoborat

Zusammenfassung Phosphinboran und Phosphoniumjodid reagieren mit NaBH₄ unter H₂-Entwicklung zu H₂P(BH₃)₂–Na⁺(I), Phenylphosphinboran zuPhHP(BH₃)₂–Na⁺ (II). Methylphosphinboran, Phenylphosphin und die Anionen von I und II reagieren nicht mit NaBH₄, da die Acidität des an Phosphor gebundenen Wasserstoffs zu gering ist. Auch (PhHP·BCl₂)₃ reagiert mit NaBH₄ unter Wasserstoffentwicklung.

---

Reaction of phosphine borane, phenylphosphine borane and phosphonium iodide with sodium tetrahydridoborate

The reaction of phosphine borane and phosphonium iodide with NaBH₄ yields H₂P(BH₃)₂–Na⁺ (I), of phenylphosphine boranePhHP(BH₃)₂–Na⁺ (II) hydrogen being evolved in both reactions. Methylphosphine borane, phenylphosphine and the anions of I and II do not react with NaBH₄ on account of the reduced acidity of the hydrogen atoms bound to phosphorus. Likewise hydrogen is evolved if (PhHP·BCl₂)₃ reacts with NaBH₄.

     

Voltamperometric determination of uranium and plutonium in alkaline solutions

The simultaneous determination of U(VI), Pu(VI), Pu(V) in 0.5–4.0 M NaOH has been elaborated by means of classical and differential pulse voltamperometry. U(VI) is determined with a dropping mercury electrode (DME) at the half-wave potential of E_1/2=–0.89 V vs. Ag/AgCl reference electrode due to reduction to U(V). The limiting current or peak heights are proportional to uranium(VI) concentration in the range of 1.3.10^–7–3·10^–4 M U(VI). Deviation from proportionality is observed for higher concentrations due to polymerization of uranates. Pu(VI) and Pu(V) are determined with a platinum rotating electrode at E_1/2=–0.02 V due to the reaction Pu(VI)+e^–»Pu(V) and with DME at E_1/2=–1.1 V due to the reduction to Pu(III). The limiting currents of both Pu(VI) and Pu(V) are proportional to their concentrations in the range of 4·10^–6–1.2·10^–3 M Pu. The determination of U(VI), Pu(VI), Pu(V) is not interfered by the presence of the following salts: 2M NaNO₃, 2M NaNO₂, 1.5M NaAlO₂, 0.5M NaF and ions of Mo(VI), W(VI), V(V), Cu(II). The presence of CrO ₄ ^2– and FeO ₂ ^– ions disturbs the determination of U(VI) in 1–4M NaOH, however, contribution of the reaction Fe(III)+e^–»Fe(II) to uranium reduction peak can be calculated from the height of the second peak Fe(II)+2 e^–»Fe(0).     

New synthesis and low temperature13C n.m.r. spectra of some anionic seven-coordinate complexes of molybdenum(II) and tungsten(II) of the type [NBu 4 n ][MI2X(CO)3L]

Summary The bisacetonitrile complexes [MI₂(CO)₃(NCMe)₂] react with an equimolar amount of L in CH₂Cl₂ at room temperature to give [MI₂(CO)₃(NCMe)L] which when mixedin situ with an equimolar amount of [NBu ₄ ⁿ ]X affords the anionic seven-coordinate compounds [NBu ₄ ⁿ ][MI₂X(CO)₃L][M=Mo or W,X=I, L=PPh₃ (for M=W only), AsPh₃ or SbPh₃ (for M=Mo only); M=Mo and W, X=Br₃ or Br₂I, L=PPh₃, AsPh₃ or SbPh₃]. These reactions are likely to occurvia the stepwise dissociative displacement of two acetonitrile ligands. Low-temperature (–70° C, CD₂Cl₂)¹³C n.m.r. spectra (CO resonances) are reported for several of the complexes in order to infer the likely stereochemistry of these compounds.     

Neutral,cationic and dicationic seven-coordinate complexes of molybdenum(II) and tungsten(II) containing mono- and bidentate nitrogen donor ligands

Summary The seven-coordinate complexes [MI₂(CO)₃(NCMe)₂] (M=Mo or W) react with two equivalents of L(L=py, 4Me-py, 3Cl-py or 3Br-py) or one equivalent of NN {NN=2,2-bipyridine(bipy), 1,10-phenanthroline(phen), 5,6-dimethyl-1, 10-phenanthroline (5,6-Me₂-1, 10-phen), 5-Nitro-1, 10-phenanthroline (5-NO₂-1, 10-phen) and C₆H₄(o-NH₂)₂ (o-diam) (for M=Mo only)} in CH₂Cl₂ at room temperature to give the substituted products [MI₂(CO)₃L₂] or [MI₂(CO)₃(NN)] (1–17) in high yield. The compounds [MI₂(CO)₃(NCMe)₂] react with two equivalents of NN (for M=W, NN=bipy; for M=Mo, NN=phen) to give the dicationic salts [M(CO)₃(NN)₂]2I(18–19). The compounds [MI₂(CO)₃(NCMe)₂] (M=Mo or W) react with two equivalents of 5,6-Me₂-1, 10-phen to yield the monocationic dicarbonyl compounds [MI(CO)₂(5,6-Me₂-phen)₂]I (20 and21). The dicationic mixed ligand complexes [M(CO)₃(bipy)(5,6-Me₂-phen)]2I (22 and23) are prepared by reacting [MI₂(CO)₃(NCMe)₂] with one equivalent of bipy, followed by anin situ reaction with 5,6-Me₂-1, 10-phen to afford the products22 and23. The complexes (1–23) described in this paper have been characterised by elemental analysis (C, H and N), i.r. spectroscopy and, in selected cases,¹Hn.m.r. spectroscopy. Magnetic susceptibility measurements show the compounds to be diamagnetic.     

Solubility of (UO2)3(PO4)2?4H2O in H+-Na+-OH?-H2PO?4-HPO2?4-PO3?4-H2O and Its Comparison to the Analogous PuO2 +2 System

The objectives of this study were to address uncertainties in the solubility product of (UO₂)₃(PO₄)₂⋅4H₂O(c) and in the phosphate complexes of U(VI), and more importantly to develop needed thermodynamic data for the Pu(VI)-phosphate system in order to ascertain the extent to which U(VI) and Pu(VI) behave in an analogous fashion. Thus studies were conducted on (UO₂)₃(PO₄)₂⋅4H₂O(c) and (PuO₂)₃(PO₄)₂⋅4H₂O(am) solubilities for long-equilibration periods (up to 870 days) in a wide range of pH values (2.5 to 10.5) at fixed phosphate concentrations of 0.001 and 0.01 M, and in a range of phosphate concentrations (0.0001–1.0 M) at fixed pH values of about 3.5. A combination of techniques (XRD, DTA/TG, XAS, and thermodynamic analyses) was used to characterize the reaction products. The U(VI)-phosphate data for the most part agree closely with thermodynamic data presented in Guillaumont et al.,⁽¹⁾ although we cannot verify the existence of several U(VI) hydrolyses and phosphate species and we find the reported value for formation constant of UO₂PO⁻₄ is in error by more than two orders of magnitude. A comprehensive thermodynamic model for (PuO₂)₃(PO₄)₂⋅4H₂O(am) solubility in the H⁺-Na⁺-OH⁻-Cl⁻-H₂PO⁻₄-HPO²⁻₄-PO³⁻₄-H₂O system, previously unavailable, is presented and the data shows that the U(VI)-phosphate system is an excellent analog for the Pu(VI)-phosphate system.     

Synthesis,spectroscopic, photophysical and electrochemical behaviour of ruthenium(II) and copper(I) isocyano-bridged complexes with polypyridine ligands: 2,2′-bipyridine and 1,10-phenanthroline

New binuclear complexes with [Cu(PPh₃)₃]⁺ and [Cu(PPh₃)(N—N)]⁺ (N—N – 2,2-bipyridine, 1,10-phenanthroline) moieties connected via the isocyanide group to [Ru(bpy)₂(py)]⁺ and [Ru(phen)₂(py)]⁺ have been prepared and isolated as PF₆ ^– salts. In addition, new trinuclear complexes, [{(PPh₃)₃Cu(-NC)}₂Ru(bpy)₂](PF₆)₂ and [{(N—N)-(PPh₃)Cu(-NC)}₂Ru(bpy)₂](PF₆)₂, have been synthesized using [Ru(bpy)₂(CN)₂]. The complexes have been characterized by elemental analyses, i.r., n.m.r., u.v.–vis., FAB mass spectra and by conductivity measurements. The i.r. spectra reveal an increase in v;(CN) in the isocyano-bridged complexes compared to the mononuclear parent complexes. The complexes are luminescent with emission wavelengths in the 458–550 and 600–636 nm ranges. The half wave reduction potentials in MeCN are always more positive than those of the parent complexes. It is observed that the isocyano-bridged complexes are more powerful excited state reductants than the cyano-bridged, Cu^(I)(-CN)Ru^(II) complexes.     

Synthesis and properties of vanadium borohydride complex NaV(BH4)4·3DME

Conclusions The anionic vanadium borohydride complex NaV(BH₄)₄,·3DME was obtained and studied employing spectrophotometry, IR spectroscopy, and derivatography.DME = 1,2-dimethoxyethane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2822–2823, December, 1978.The authors express their gratitude to V. I. Berestenko for taking the derivatograms and discussing the obtained results.     

Temperature and ionic strength influence on U(VI/V) and U(IV/III) redox potentials in aqueous acidic and carbonate solutions

Redox potentials: E(UO ₂ ²⁺ /UO ₂ ⁺ )=60±4 mV/NHE, E(U⁴⁺/U³⁺)=–630±4mV/NHE measured at 25°C in acidic medium (HClO₄ 1M) using cyclic voltametry are in accordance with the published data. From 5°C to 55°C the variations of the potentials of these systems (measured against Ag/AgCl electrode) are linear. The entropies are then constant: [S(UO ₂ ²⁺ /UO ₂ ⁺ )–S(Ag/AgCl)]/F=0±0.3 mV/°C, [S(U⁴⁺/U³⁺)–S(Ag/AgCl)]/F=1.5±0.3 mV/°C. From 5°C to 55°C, in carbonate medium (Na₂CO₃=0.2M), the Specific Ionic Interaction Theory can model the experimental results up to I=2M (Na⁺, ClO ₄ ^– , CO ₃ ^2– ): E(UO₂(CO₃) ₃ ^4– /UO₂(CO₃) ₃ ^5– )=–778±5 mv/NHE (I=0, T=25°C, (25°C)=(UO₂(CO₃) ₃ ^4– , Na⁺)–(UO₂(CO₃) ₃ ^5– , Na⁺)=0.92 kg/mole, S(UO₂(CO₃) ₃ ^4– /UO₂(CO₃) ₃ ^5– =–1.8±0.5 mV/°C (I=0), =(Cl^–, Na⁺)=(1.14–0.007T) kg/mole. The U(VI/V) potential shift, between carbonate and acidic media, is used to calculate (at I=0,25°C):

Reactions of dimethyl(dimethylsulphoxide)pentamethylcyclopentadienyl-rhodium and -irridum with acids

The complexes [C₅Me₅MMe₂(Me₂SO)] (Ia, M = Rh; Ib, M = Ir) react with p-toluenesulphonic acid in acetonitrile to give [C₅Me₅MMe(Me₂SO)(MeCN)]⁺, (II), and with trifluoroacetic acid to give first [C₅Me₅MMe(Me₂SO)(O₂CCF₃)] and then [C₅Me₅M(Me₂SO)(O₂CCF₃)₂]. Complexes II react with halide (X^?) to give the halomethyl complexes [C₅Me₅MMe(X)(Me₂SO)]. The IR, far-IR, ¹H and ¹³C NMR spectra are all in agreement with structures proposed.     

Amino acid complexes of ruthenium: synthesis, characterization and cyclic voltammetric studies

Reaction of α-amino acids (HL) with [Ru(PPh₃)₃Cl₂] in the presence of a base afforded a family of complexes of type [Ru(PPh₃)₂(L)₂]. These complexes are diamagnetic (low-spin d⁶, S=0) and show ligand-field transitions in the visible region. ¹H and ³¹P NMR spectra of the complexes indicate the presence of C₂ symmetry. Cyclic voltammetry on the [Ru(PPh₃)₂(L)₂] complexes show a reversible ruthenium(II)–ruthenium(III) oxidation in the range 0.30–0.42 V vs. SCE. An irreversible ruthenium(III)–ruthenium(IV) oxidation is also displayed by two complexes near 1.5 V vs. SCE.     

Synthesis and characterization of mononuclear cadmium(II) and dinuclear uranyl(VI) complexes with <Emphasis Type="Italic">vic</Emphasis>-dioximes

In this study, the mononuclear complexes of cadmium(II) and dinuclear complexes of uranyl(VI) with five vic-dioximes have been obtained. Cadmium(II) forms, with ligands, complexes [(L ^xH)(Cl)(H₂O)(Cd)] with x=1–5. Mononuclear complexes with a metal: ligand ratio of 1:1 were obtained for cadmium(II) with the ligands, and a chloride ion and a water molecule are also coordinated to the cadmium(II) ions. Uranyl(VI) complexes of these ligands are a dinuclear structure with μ-hydroxo-bridges. Uranyl(VI) forms, with ligands, complexes [(L^xH)₂(OH)₂(UO₂)₂] with x=1–5, which have a 2:2 metal:ligand ratio. The structures of the complexes were identified by elemental analysis, i.r., and ¹H-n.m.r. spectra, u.v.–vis. spectroscopy, magnetic susceptibility measurements, conductivity measurements and thermogravimetric analysis (t.g.a.).     

Lewis-base properties of the HFe3(CO)9S− and Fe3(CO)9S2− cluster anions

Summary The HFe₃(CO)₉S^– and Fe₃(CO)₉S^2– anions [prepared from H₂Fe₃(CO)₉S by deprotonation] react with M(CO)₅(THF) (M=Cr or W) to form the anionic capped clusters, HFe₃(CO)₉SM(CO) ₅ ^– and Fe₃(CO)₉SM(CO) ₅ ^2– , which can be isolated as their Et₄N salts. The M-S bonds of these complexes are cleaved by ligands such as PPh₃ or MeCN. The dianionic clusters are more stable than their monoanionic analogues. Alkylation of Fe₃(CO)₉S^2– with alkyl halides followed by protonation yields HFe₃(CO)₉SR complexes, among them the first member of the series with R=Me.     

Kinetics and mechanism of ligand substitution of mono(polyamine)-nickel(II) complexes with 4-(2-pyridylazo)resorcinol

Summary The kinetics and mechanism of ligand substitution reactions of tetraethylenepentamine nickel(II), Ni (Teren), and triethylenetetraamine nickel(II), Ni(Trien), with 4-(2-pyridylazo)resorcinol (parH₂) have been studied spectrophotometrically at I=0.1 M (NaClO₄) at 25°C. In both systems two distinct reaction steps are observed. The rapid first step follows the rate law d[Ni(Polyamine)(ParH₂)]/dt=k₁ [Ni(Polyamine)] [ParH₂]. The formation of ternary complexes of Ni (Polyamine) with ParH₂ has been investigated under second order equal concentration conditions. The values of second order rate constants for the Trien and Teren reactions are (2.1±0.2)×10⁴ M^–1s^–1 and (7.8±0.6)×10³ M^–1s^–1 respectively at pH=9.0, I=0.1 M and 25°C.The rate law for the second step may be written as d[Ni(Par)₂]/dt=k₂[Ni(Polyamine)(ParH₂)]. Values of k₂ for the Trien and Teren systems are (2.5±0.1)×10^–4 s^–1 and (4.76±0.3)×10^–5 s^–1 respectively.     

Kinetics and mechanism of electroreduction of ethylenediamine and hydroxyethylenediamine complexes of zinc(II) on a dropping-mercury electrode

The kinetics of electroreduction of ethylenediamine and hydroxyethylenediamine complexes of zinc(II) on a dropping-mercury electrode (DME) in 1 M NaClO₄ solutions of pH 9–11.5 is studied at different ethylenediamine concentrations at 25, 35, and 50°C. One wave with a diffusion limiting current is observed at an overall concentration of zinc(II) complexes of 2 × 10^–5 M and current recording times t ₁ = 0.3–4 s. The polarographic peak that distorts the wave at t ₁ 0.5 s, pH 11.5, and 25°C is due to the accumulation of insoluble reduction products on the electrode surface. The slow electrochemical step on DME involves complexes Znen²⁺, which form in preceding reversible chemical steps from complexes present in solution.__________Translated from Elektrokhimiya, Vol. 41, No. 4, 2005, pp. 397–405.Original Russian Text Copyright © 2005 by Kurtova, Kravtsov, Tsventarnyi.     

Kinetics and mechanisms of oxidation by metalions. Part XI(1). Kinetics of the osmium(VIII)-catalysed oxidation of glycols by alkaline hexacyanoferrate(III)

Summary The kinetics of the Os^VIII-catalysed oxidation of glycols by alkaline hexacyanoferrate(III) ion exhibits zerothorder dependence in [Fe(CN) ₆ ^3– ] and first-order dependence in [OsO₄]. The order with respect to glycols is less than unity, whereas the rate dependence on [OH^–] is a combination of two rate constants; one independent of and the other first-order in [OH^–]. These observations are commensurate with a mechanism in which two complexes, [OsO₄(H₂O)G]^– and [OsO₄(OH)G]^2–, are formed either from [OsO₄(H₂O)(OH)]^– or [OsO₄(OH)₂]^2– and the glycol GH, or by [OsO₄(H₂O)₂] and [OsO₄(H₂O)(OH)]^– and the glycolate ion, G^–, which is in equilibrium with the glycol GH through the reaction between GH and OH^–. Hence there is an ambiguity about the true path for the formation of the two Os^VIII-glycol complexes. A reversal in the reactivity order of glycols in the two rate-determining steps, despite the common attack of OH^– ion on the two species of Os^VIII-complexes, indicates that the two complexes are structurally different because S changes from the negative (corresponding to k₁₁) to positive (related to k₂).     

Synthesis,characterization and antimicrobial activity of cobalt(II), nickel(II)and copper(II) complexes with new asymmetrical Schiff base ligands derived from 7-formyanil-substituted diamine-sulphoxine and acetylacetone

Asymmetric 7-formyanil-substituted-imino-4-(4-methyl-2-butanone)-8-hydroxyquinoline-5-sulphonic acid (Schiff bases), react with Co^II, Ni^II and Cu^II ions to give 1:2, 1:1 and 2:1 complexes as established by conductometric titrations in 1:1 DMF:H₂O. The complexes were investigated by elemental analyses, molecular weight determinations, molar conductance, magnetic moments, thermal analysis, i.r., u.v.–vis. and e.s.r. spectra. The complexes have an octahedral crystal structure and general formula [ML·(OH₂)₂], where M^II = Co, Ni and Cu, and L = Na[7—X—HL], (—X— = (CH₂)₂, (CH₂)₃, p-C₆H₄, o-C₆H₄). Antimicrobial activity of these new ligands and their transition metal complexes has been screened in vitro on common fungi and bacteria.     

Bis(η5‐isopropyltetramethylcyclo­pentadienyl)(tetrahydroborato‐κ3H,H′,H′′)(tetrahydrofuran‐O)‐samarium(III): a lanthanidocene complex with a tridentate tetrahydroborato ligand

The lanthanidocene complex [Sm(BH₄)(C₁₂H₁₉)₂(C₄H₈O)], (I), shows a distorted tetrahedral arrangement around the central Sm^III atom. It consists of two η⁵‐isopropyltetramethylcyclopentadienyl ligands, one tetrahydroborato (BH₄^?) ligand bridging via H atoms to the lanthanide atom and one coordinating tetrahydrofuran (thf) molecule. The BH₄^? unit of (I) coordinates as a tridentate ligand with three bridging H atoms and one terminal H atom [Sm—B—H4 176 (2)°]. The η⁵‐isopropyl­tetra­methylcyclopentadienyl ligands of this bent‐sandwich complex [Cp1—Sm—Cp2 133.53 (1)° where Cp denotes the centroid of the cyclopentadienyl ring] adopt staggered conformations.     

Metal chelates in adsorption polarography I: Mo(VI) and derivatives of oxine

The formation of complexes between Mo(VI) and 8-hydroxy-quinoline (oxine) and four oxine derivatives were investigated by multiwavelength molecular absorption spectrometry, potentiometry, and polarography. The following pK_OH- and pK_NH- values of the ligands and logK ₂₁₁-values of the complexes MoO₂(OH)₂L ^x– (x=1 or 2) were obtained at 25° C and an ionic strength of 1M(NaClO₄): 5,7-dinitro8-hydroxyquinoline 4.59, <0, 14.50; 7-nitro-8-hydroxyquinoline-5-sulfonic acid 5.34, 0.41, 15.70; 7-iodo-8-hydroxyquinoline-5-sulfonic acid 6.98, 2.62, 17.65; 8-hydroxyquinoline-5-sulfonic acid 8.33, 4.13, 18.71; and 8-hydroxyquinoline 9.62, 5.28, 19.69. A good linearity was found between logK ₂₁₁ and the sum of the pK-values of the OH- and NH⁺-groups. The dependence of the peak current of Mo(VI)-determinations by adsorption polarography of the 7-nitro-8-hydroxyquinoline-5-sulfonate complex of Mo(VI) MoO(OH)₃L^– can quantitatively be described at pH 0.8–2 using the corresponding pK-values and the log K₃₁₁ of 18.54±0.03, determined by polarography.     

Superhalogens as building blocks of complex hydrides for hydrogen storage

Superhalogens are species whose electron affinity (EA) or vertical detachment energy (VDE) exceeds those of halogens. These species typically consist of a central electropositive atom with electronegative ligands. The EA or VDE of species can be further increased by using superhalogens as ligands, which are termed as hyperhalogens. Having established BH₄⁻ as a superhalogen, we have studied BH_4 − x(BH₄)_x⁻ (x = 1–4) hyperhalogen anions and their Li-complexes LiBH_4 − x(BH₄)_x using density functional theory. The VDE of these anions is larger than that of BH₄⁻, which increases with the increase in number of peripheral BH₄ moieties (x). The hydrogen storage capacity of LiBH_4 − x(BH₄)_x complexes is higher but binding energy is smaller than that of LiBH₄, a typical complex hydride. The linear correlation between the dehydrogenation energy of LiBH_4 − x(BH₄)_x complexes and the VDE of BH_4 − x(BH₄)_x⁻ anions is established. These complexes are found to be thermodynamically stable against dissociation into LiBH₄ and borane. This study demonstrates the role of superhalogens in designing new materials for hydrogen storage and should also motivate experimentalists to synthesize LiBH_4 − x(BH₄)_x (x = 1–4) complexes.     

Reactions of [WI2(CO)(NCMe)(η2-RC2R)2] (R = Me or Ph) with carbon monoxide to give either [WI2(CO)2(η2-MeC2Me)2] or [W(-I) I(CO) (η2-PhC2Ph)2]2. Crystal structure of [WI2(CO) 2( η2-MeC2Me)2]

The complexes [WI₂(CO)(NCMe)(η2)-RC₂R)₂] (R = Me and Ph) react in CH₂Cl₂ with an excess of carbon monoxide to give initially the acetonitrile substituted products [WI₂(CO)₂(η²-RC₂R) ₂]. For R= Me, the complex [WI₂(CO)₂(η²- MeC₂Me)₂] (1) was isolated and its structure determined by X-ray crystallography. However, for R = Ph, dimerisation occurs to give the iodide-bridged compound [W(μ-I)I(CO)(η²-PhC₂Ph)₂]₂ (2) with loss of carbon monoxide. These reactions are reversible as 1 and 2 react with acetonitrile to give [WI₂(CO)(NCMe)(η²-RC₂R)₂]. The ¹³C NMR spectra of I and 2 indicate that the two alkyne ligands donate a total of six electrons to the tungsten in these complexes.