Coordination Chemistry of Homoleptic Actinide(IV)–Thiocyanate Complexes

The synthesis, X‐ray crystal structure, vibrational and optical spectroscopy for the eight‐coordinate thiocyanate compounds, [Et₄N]₄[Pu^IV(NCS)₈], [Et₄N]₄[Th^IV(NCS)₈], and [Et₄N]₄[Ce^III(NCS)₇(H₂O)] are reported. Thiocyanate was found to rapidly reduce plutonium to Pu^III in acidic solutions (pH<1) in the presence of NCS^?. The optical spectrum of [Et₄N][SCN] containing Pu^III solution was indistinguishable from that of aquated Pu^III suggesting that inner‐sphere complexation with [Et₄N][SCN] does not occur in water. However, upon concentration, the homoleptic thiocyanate complex [Et₄N]₄[Pu^IV(NCS)₈] was crystallized when a large excess of [Et₄N][NCS] was present. This compound, along with its U^IV analogue, maintains inner‐sphere thiocyanate coordination in acetonitrile based on the observation of intense ligand‐to‐metal charge‐transfer bands. Spectroscopic and crystallographic data do not support the interaction of the metal orbitals with the ligand π system, but support an enhanced An^IV–NCS interaction, as the Lewis acidity of the metal ion increases from Th to Pu.     

Photoelectron spectroscopy of f-element organometallic compounds II. Tricyclopentadienyl derivatives of uranium(IV) and thorium(IV)

The photoelectron spectra of some cyclopentadienyI derivatives of uranium(IV) and thorium(IV), namely (C₅H₅)₃ ThCl, (C₅H₅)₃ UCl, (C₅ H₄ CH₃)₃ ThCl, (C₅ H₄ CH₃)₃ UCl, (C₅ H₄ CH₃)₃ UBr and (C₅ H₄ CH₃ )₃ UBH₄, are reported the metal 5f ionization has been detected in all the uranium derivative spectra and a simple molecular orbital scheme qualitatively accounts for the number and position of the observed low energy bands.     

Photoelectron spectroscopy of actinide organometallic compounds I. Bis(cyclooctatetraene)actinide(IV) complexes

The He(I) photoelectron spectra of the antinocene species Th(cot)₂ and U(cot)₂ (cot = cyclooctatetraene) have been determined. The 5f metal ionization has been detected at the onset of the uranocene spectrum. The low ionization energy region of both spectra is discussed in terms of simple qualitative molecular orbital scheme.     

Complexes of organometallic compounds : XXXIX. synthesis,infrared and mössbauer studies on monoorganotin(IV) complexes with tridentate ligands

Novel complexes RClSntrid, where R is Me, Ph, n-Oct, and trid^2? are dianions of tridentate “planar” ligands with ONO and SNO donor atoms, were synthesized and investigated in the solid state by infrared and Mössbauer spectroscopy. Possible configurations are discussed; polymeric trigonal bipyramidal structures seem to occur, although five-coordinated monomers as well as octahedral dimers (via oxygen or sulfur bridges) are not excluded.     

Reversible radical complex formation of an organometallic diplatinum(IV) compound

Crystallographically characterized anti-[(μ-bmptz){fac-PtBrMe₃}₂], bmptz = 3,6-bis(2-(4-methylpyridyl))-1,2,4,5-tetrazine, could be reversibly reduced at −0.36 V vs. [FeCp₂]^+/° in CH₂Cl₂/0.1 M Bu₄NPF₆ to a persistent anion. Despite the presence of two conjugatively coupled platinum(IV) centers and the bromide ligands as potential leaving groups it is the bridging bmptz ligand which accepts the added electron within the tetrazine ring as evident from EPR and UV-Vis spectroelectrochemistry of that diplatinum(IV) radical complex. The function of the methyl groups in the [fac-PtMe₃]⁺ ions is discussed in contrast with the related entity [fac-Re(CO)₃]⁺.     

Studies on complex compounds of thorium(IV) with pyridine and quinoline carboxylic acid. Part I

Summary Thorium acetylacetonate [Th(acac)₄] reacts with pyridine carboxylic acids in acetone giving eight coordinate thorum(IV) complexes of the compositions [Th(pic)₄] and [Th(picO)₄] (picH = picolinic acid, picOH = picolinic acidN-oxide). The complex [Th(dip)₂] · 3H₂O (dipH₂ = pyridine-2,6-dicarboxylic acid) is also reported. Thorium(IV) complexes of the types [Th(quin)₂] · 2H₂O and [Th(quind)₂(acac)₂] (quinH₂ = quinolinic acid or pyridine-2,3-dicarboxylic acid, quindH = quinaldinic acid) were prepared by the interaction of [Th(acac)₄] with the respective acids in acetone. The lower solubility and i.r. spectral studies of the complex [Th(quin)₂] · 2 H₂O suggest that it is polymeric.     

Polymerization of substituted olefins initiated by organometallic compounds of titanium (IV)

Polymerization tests were carried out in homogeneous systems on various substituted olefins CH₂=CRZ (R = H or CH₃; Z = CN, COOR, C₆H₅ or OCOR) with compounds of titanium (IV) Ti X_4?x Y_x (X and/or Y = Cl, OR, NR₂, C₅H₅, OCH₂ CF₃, CH₃, C₆H₅ …) or with the bimetallic complex CH₃Ti(OR)₃, Al(CH₃)₃. The activity of the initiator varies with the co-ordination environment of the titanium and to a considerable extent with the functional groups linked to the olefin.     

Molecular orbitals and photoelectron spectra of some titanium(IV) organometallic compounds

The photoelectron spectra of some titanium(IV) organometallic compounds are reported, and the data and the bonding in the compounds are discussed with the aid of extended CNDO/2 calculations.     

焦磷酸盐水溶液中稳定Pr(IV)和Tb(IV)的研究

本文报道了在焦磷酸盐的碱性水溶液中用O~3氧化Pr(III)和Tb(III),从而得到Pr(IV)-P~2O~7^4^-和Tb(IV)-P~2O~7^4^-的配合物溶液,通过对溶液进行化学分析及吸收光谱的研究,证明了溶液中有Pr(IV)和Tb(IV)的存在,其持征吸收分别为λmax=365nm,摩尔消光系数ε=1205L/mol.cm;/.pr(iv)=257nm,ε=929L/mol.cm.在碱性条件下,Pr(IV)和Tb(IV)的还原反应均为拟一级反应.用动力学方法测定了不同条件下Pr(IV)和Tb(IV)的还原速率常数和半衰期,从而探讨了稳定Pr(IV)和Tb(IV)的条件.同时还测定了在反应条件下Pr(IV)/Pr(III)和Tb(IV)/Tb(III)电对的克式电位。     

on the existence of organometallic palladium(IV) complexes

The reactions of palladium(II) compounds of the type Cl₂PdL₂ with bromobis(pentafluorophenyl)thallium(III) has been reexamined. The reported preparation of the organo palladium(IV) complex Cl₂Pd(C₆F₅)₂(PPh₃)₂ could not be repeated, and instead mixtures of binuclear palladium(II) compounds, Cl₂Pd(C₆F₅)₂L₂, and mononuclear palladium(II) compounds were obtained. The binuclear are transformed into the mononuclear complexes on addition of an excess of ligand L.The chlorine bridging atoms of the binuclear complexes can be replaced by other halogens or pseudohalogens by treatment with salts of the MX type (X = Br, I, SCN).     

Studies on Carboxylato Complexes of Tricyclopentadienyl Cerium (IV) Chloride and Bisindenyl Cerium (IV) Dichloride

Tricyclopentadienyl Cerium (IV) chloride and bisindenyl cerium (IV) dichloride have been treated with sodium salts of the appropriate carboxylic acids in benzene or tetrahydrofuran medium to give (C₅H₃)₃ Ce(R) and (C₉H₇)₂Ce(R)₂ wherein R is HCOO, CH₃COO, C₂H₅COO, C₃H₇COO and C₆H₅COO. The infrared spectra, thermal stabilities and other characteristics of the above compounds have been studied and reported.     

Complexes of Nickel(II) Thiocyanate with Anilines

Complexes of the type NiL₂(SCN)₂ (L = aniline, o-, m-, p-toluidine, o-, m-, p-anisidine and p-phenetidine) have been prepared and characterised by room temperature magnetic moments and infra-red spectral data (down to 250 cm^?1) in the solid state. The thiocyanate is present as a bridging group and the metal atom is shown to be in a six-coordinate environment having an octahedral stereochemistry.     

Complexes of organometallic compounds : XXXVII. Mössbauer and other studies on adducts of organotin(IV) chlorides with N,N′-ethylenebis(salicylideneiminato)-nickel(II)

Novel 1/1 adducts have been obtained from the complex N,N′-ethylenebis(salicylideneiminato)nickel(II) (NiSalen) with di- and mono-organotin(IV) chlorides, and their solid state configuration investigated by Mössbauer , IR and electronic spectroscopy and magnetic measurements. In coordinated NiSalen the square planar structure is maintained around Ni^II, and the coordination to tin involves three-coordinate phenolic oxygens. The environment of Sn^IV is judged to be octahedral in both types of compounds. A trans-R₂, cis-Cl₂ configuration is advanced for R₂SnCl₂NiSalen.     

Alkylation reactions with organometallic compounds : IV. The reaction of tris(triphenylphosphine)methylcobalt with diphenylacetylene

Tris(triphenylphosphine)methylcobalt;(Ph₃P)₃CoCH₃, reacts with diphenyl-acetylene to give α-methylstilbene as the sole addition product.(Ph₃P)₃CoCH₃ can be used as an alkylation reagent in ethers or in aromatic solvents.     

Electronic influences in the molecules of group IV organometallic compounds

On the basis of an analysis of the characteristic properties in the vibrational and NMR spectra of some hydrides and alkyl and vinyl derivatives of C, Si, Ge, and Sn(M), an explanation is given for an effect which appears in the organic compounds of Group IV B elements as due to an increase in the electron-acceptor properties of the heteroatoms.     

Thiocyanate complexing of Np(IV) and Pu(III)

The thiocyanate complexing of Np(IV), at μ = 2.0 and [H⁺] = 1.0 M, has been studied by solvent extraction method, using thenoyltrifluoroacetone (TTA) and dinonylnaphthalene-sulphanic acid (DNNS), and that of Pu(III), under similar conditions, using DNNS. Data indicate the formation of three successive complexes between Np(IV) and SCN⁻ with the overall stability constants 31.3 ± 4.9, 114.7 ± 20.7 and 340.9 ± 18.3. Pu(III) seems to form only one complex upto [SCN⁻] ⩽ 0.4 M, with the stability constant value of 2.14 + 0.15, whereas further complexing appears to occur at higher concentrations of SCN⁻; the β₂ is estimated to be about 0.5. Spectrophotometric and solvent extraction data obtained further confirmed the thiocyanate complexing of these two ions. The thermodynamic constants associated with the complex formation of Np(IV) with thiocyanate have also been determined.     

Mössbauer Spectroscopic Studies of the Hydroxofluorostannate(IV) Complexes

Mössbauer isomer shifts of ¹¹⁹Sn in a series of complexes K₂Sn(OH)_6-mF_m observed at 78 K were ?0.05, ?0.05, ?0.24, ?0.27 and ?0.40 mm s^?1, respectively, for m=0, 2, 4, 5 and 6. These IS values were linearly related to both m and (the average Pauling electronegativity of the ligands): . The IS straight line was compatible within experimental error with the one reported by Parish and Row-botham for the hexahalogenostannate complexes SnX₄Y₂², namely, The revised IS straight line including both series of complexes could be expressed by the equation Quadrupole splittings observed in the complexes of m = 2,4 and 5 were 1.16, 0.80 and 0.73 mm s^?1 respectively. They were linearly related to both m and .