Crystal Structure of the Mixed-Valence Neptunium Compound Na6[(NpVO2)2(NpVIO2)(MoO4)5] · 13H2O

The crystal structure of the mixed-valence Np(V) and Np(VI) compound Na₆[(Np^VO₂)₂(Np^VIO₂)(MoO₄)₅] · 13H₂O was determined. The structure is built of the anionic layers [(Np^VO₂)₂(Np^VIO₂)(MoO₄)₅] ^6n- _n with the Na⁺ cations and crystal water molecules between them. The Np(V) and Np(VI) atoms in the anionic layers are ordered. The motif of the anionic layer is close to that found in Mg₂[(UO₂)₃(SeO₄)₅] · 16H₂O. The isostructural mixed-valence Np(V) and U(VI) compound was also synthesized.     

Interaction of Aluminium (III) with the f-Family Ions Np(VI), Pu(VI), Np(V), Np(IV), Pu(IV), Nd(III), and Am(III) in the Course of Simultaneous Hydrolysis

The interaction of Np(VI), Pu(VI), Np(V), Np(IV), Pu(IV), Nd(III), and Am(III) with Al(III) in solutions at pH 0–4 was studied by the spectrophotometric method. It was shown that, in the range of pH 3–4, the hydrolyzed forms of neptunyl and plutonyl react with the hydrolyzed forms of aluminium. In the case of Pu(VI), the mixed hydroxoaqua complexes (H₂O)₃PuO₂(-OH)₂Al(OH)(H₂O)₃ ²⁺ or (H₂O)₄PuO₂OAl(OH)(H₂O)₄ ²⁺ are formed at the first stage of hydrolysis. Np(VI) also forms similar hydroxoaqua complexes with Al(III). The formation of the mixed hydroxoaqua complexes was also observed when Np(IV) or Pu(IV) was simultaneously hydrolyzed with Al(III) at pH 1.5–2.5. The Np(IV) complex with Al(III) has, most likely, the formula (H₂O) _n (OH)Np(-OH)₂Al(OH)(H₂O)₃ ³⁺. At pH from 2 to 4.1 (when aluminium hydroxide precipitates), the Np(V) or Nd(III) ions exist in solutions with or without Al(III) in similar forms. When pH is increased to 5–5.5, these ions are almost not captured by the aluminium hydroxide precipitate.     

Determination of stability constants of U(VI), Np(VI) and Pu(VI) with chloride ions by extraction chromatography

The complex formation of U(VI), Np(VI) and Pu(VI) with chloride ions was studied in HClO₄−HCl solutions at ionic strength of 2.0 and [H⁺]=2.0M by the method of extraction chromatography using dilute HDEHP as the stationary phase.     

Electron transfer dissociation of dipositive uranyl and plutonyl coordination complexes

Reported here is a comparison of electron transfer dissociation (ETD) and collision‐induced dissociation (CID) of solvent‐coordinated dipositive uranyl and plutonyl ions generated by electrospray ionization. Fundamental differences between the ETD and CID processes are apparent, as are differences between the intrinsic chemistries of uranyl and plutonyl. Reduction of both charge and oxidation state, which is inherent in ETD activation of [An^VIO₂(CH₃COCH₃)₄]²⁺, [An^VIO₂(CH₃CN)₄]², [U^VIO₂(CH₃COCH₃)₅]²⁺ and [U^VIO₂(CH₃CN)₅]²⁺ (An = U or Pu), is accompanied by ligand loss. Resulting low‐coordinate uranyl(V) complexes add O₂, whereas plutonyl(V) complexes do not. In contrast, CID of the same complexes generates predominantly doubly‐charged products through loss of coordinating ligands. Singly‐charged CID products of [U^VIO₂(CH₃COCH₃)_4,5]²⁺, [U^VIO₂(CH₃CN)_4,5]²⁺ and [Pu^VIO₂(CH₃CN)₄]²⁺ retain the hexavalent metal oxidation state with the addition of hydroxide or acetone enolate anion ligands. However, CID of [Pu^VIO₂(CH₃COCH₃)₄]²⁺ generates monopositive plutonyl(V) complexes, reflecting relatively more facile reduction of Pu^VI to Pu^V. Copyright © 2011 John Wiley & Sons, Ltd.     

First observation of intra-5f fluorescence from an actinyl center: Np(VI) near-IR emission in Cs2U(Np)O2Cl4

Fluorescence from an excited 5f state of Np(VI) has been observed in the doped impurity system Cs₂U(Np)O₂Cl₄. This is the first intra-5f fluorescence transition that has been detected at room temperature in a condensed-phase system with an actinyl (An(VI)O₂²⁺) core, and it is a rare example of fluorescence of any kind from non-uranyl ions of this type. The emission originates from an excited state approximately 6890 cm⁻¹ above the ground state. Its emission spectrum and fluorescence lifetime at 295 K will be discussed. Vibronic structure in the emission spectrum is assigned based on comparison with the detailed analysis of the absorption spectra published by Denning et al.     

Influence of Coordination Geometry on the Ring Opening of Benzoxazine: Oxidovanadium(V), Dioxidomolybdenum(VI) and Dioxidotungsten(VI) Complexes of Benzoxazine Based Ligands and their Bio Inspired Catalytic Applications

Mono benzoxazine appended N-capped amino bis(disubstitutedphenol) ligands [ II ( a–c )] upon reaction with V^VO(OEt)₃ in a 1 : 1 molar ratio in EtOH/MeOH give [{V^VO}en(3,5-dtbb)₃] ( 1 ), [{V^VO}en(3-tb,5-mb)₃] ( 2 ) and [{V^VO}en(3,5-dmb)₃] ( 3 ). During the reaction, the benzoxazine ring opens with the loss of methylene group and the newly formed ligands, N,N-bis(2-hydroxy-3,5-disubstitutedbenzyl)-N’-2-hydroxy-3,5-disubstituted benzyledene-1,2-diaminoethane [ III ( a–c )], behave as tribasic pentadentate in these complexes. Under similar conditions, when [M^VIO₂(acac)₂] (M=Mo or W; Hacac=acetylacetone) reacts with II ( a–c ), these ligands retain their identity and form cis-[M^VIO₂] complexes, [{Mo^VIO₂}{en(3,5-dtbb)₂(6,8-dtbbenzox)}] ( 4 ), [{Mo^VIO₂}{en(3-tb,5-mb)₂(6-tb,8-mbbenzox)}] ( 5 ) and [{Mo^VIO₂}{en(3,5-dmb)₂(6,8-dmbenzox)}] ( 6 ), [{W^VIO₂}{en(3,5-dtbb)₂(6,8-dtbbenzox)}] ( 7 ), and [{W^VIO₂}{en(3-tb,5-mb)₂(6-tb,8-mbbenzox)}] ( 8 ). However, the benzoxazine ring ruptures in case of ligand IIc under these conditions and form [{W^VIO₂}{en(3,5-dmb)₃}] ( 10 ), similar to complexes 1–3 . Complex [{W^VIO₂}{en(3,5-dmb)₂(6,8-dmbenzox)}] ( 9 ), having structure similar to 4–8 , could only be obtained when the reaction was carried out in toluene. Not only 9 , even complexes 4–8 can be isolated in toluene. Rupturing of both benzoxazine rings has also been experienced when ligands 1,2-bis(6,8-disubstitutedbenzo[e][1,3]oxazin-3(4H)-yl)ethane [ I ( a–c )] react with [M^VIO₂(acac)₂] (M=Mo or W) in MeOH and give salan type complexes [(M^VIO₂)en(3,5-dtbb)₂] [M=Mo ( 11 ), M=W ( 14 )], [(M^VIO₂)en(3-tb,5-mb)₄] [M=Mo ( 12 ), M=W ( 15 )] and [(M^VIO₂)en(3,5-dmb)₄] [M=Mo ( 13 ), M=W ( 16 )]. Complexes 1–9 have been used as catalyst for the multicomponent Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) and oxidative bromination of phenol derivatives.     

Dioxomolybdenum(VI) complexes of 2-hydroxybenzaldehyde 4-phenyl-S-methylthiosemicarbazone

Mixed ligand complexes of dioxomolybdenum(VI) with 2-hydroxybenzaldehyde 4-phenyl-S-methylthiosemicarbazone (H₂L) were prepared with the formula [MoO₂(L)D] (D = H₂O, methyl, n-butyl, and n-undecyl alcohol, DMF, DMSO, pyridine, 4-picoline, and 3,5-lutidine). The compounds were characterized by elemental analysis, IR and ¹H NMR spectroscopy. The thermal decomposition of the compounds were investigated by using TGA, DTG, and DTA methods in air, and the thermal behavior depending on the second ligand molecule was discussed. A single crystal of the DMF coordinated complex was studied by X-ray diffractometry. The text was submitted by the authors in English.     

Preparation and Crystal Structures of the Hydrous Mercury Tellurates,HgII(H4TeVIO6) and HgI2(H4TeVIO6)(H6TeVIO6)·2H2O

Single crystals of Hg^II(H₄Te^VIO₆) (colourless to light‐yellow, rectangular plates) and Hg^I₂(H₄Te^VIO₆)(H₆Te^VIO₆)·2H₂O (colourless, irregular) were grown from concentrated solutions of orthotelluric acid, H₆TeO₆, and respective solutions of Hg(NO₃)₂ and Hg₂(NO₃)₂. The crystal structures were solved and refined from single crystal diffractometer data sets (Hg^II(H₄Te^VIO₆): space group Pna2₁, Z = 4, a =10.5491(17), b = 6.0706(9), c = 8.0654(13)Å, 1430 structure factors, 87 parameters, R[F² > 2σ(F²)] = 0.0180; Hg^I₂(H₄Te^VIO₆)(H₆Te^VIO₆)·2H₂O: space group P1¯, Z = 1, a = 5.7522(6), b = 6.8941(10), c = 8.5785(10)Å, α = 90.394(8), β = 103.532(11), γ = 93.289(8)°, 2875 structure factors, 108 parameters, R[F² > 2σ(F²)] = 0.0184). The structure of Hg^II(H₄Te^VIO₆) is composed of ribbons parallel to the b axis which are built of [H₄TeO₆]^2— anions and Hg²⁺ cations held together by two short Hg—O bonds with a mean distance of 2.037Å. Interpolyhedral hydrogen bonding between neighbouring [H₄TeO₆]^2— groups, as well as longer Hg—O bonds between Hg atoms of one ribbon to O atoms of adjacent ribbons lead, to an additional stabilization of the framework structure. Hg^I₂(H₄Te^VIO₆)(H₆Te^VIO₆)·2H₂O is characterized by a distorted hexagonal array made up of [H₄TeO₆]^2— and [H₆TeO₆] octahedra which spread parallel to the bc plane. Interpolyhedral hydrogen bonding between both building units stabilizes this arrangement. Adjacent planes are stacked along the a axis and are connected by Hg₂²⁺ dumbbells (d(Hg—Hg) = 2.5043(4)Å) situated in‐between the planes. Additional stabilization of the three‐dimensional network is provided by extensive hydrogen bonding between interstitial water molecules and O and OH‐groups of the [H₄TeO₆]^2— and [H₆TeO₆] octahedra. Upon heating Hg^I₂(H₄Te^VIO₆)(H₆Te^VIO₆)·2H₂O decomposes into TeO₂ under formation of the intermediate phases Hg^II₃Te^VIO₆ and the mixed‐valent Hg^IITe^IV/VI₂O₆.     

Oxomolybdenum(VI) and oxomolybdenum(V) thiocarbohydrazone complexes

Summary Dioxomolybdenum(VI) complexes [MoO₂L]H₂O and oxomolybdenum(V) complexes [Mo₂O₃L₂]H₂O and [Mo₂O₃(LH)₂(OH)₂(H₂O)₂] (where LH₂=thiocarbohydrazones derived from thiocarbohydrazide with salicylaldehyde, 5-methyl-, 5-chloro-, 5-bromo-, 3-methoxysalicylaldehyde and 2-hydroxy-1-naphthaldehyde) have been prepared and characterised by elemental analysis, conductivity, magnetic moment, i.r., u.v-vis, e.p.r. and thermal studies. The data suggests that molybdenum(VI) complexes are non electrolytes, diamagnetic, monomeric and have distorted octahedral geometry, whereas the molybdenum(V) complexes are non electrolytes, paramagnetic and have distorted octahedral structures with possible metal intereaction via oxo bridging.     

Hydrogen‐bonded network structures in dipyridinium,bis(2‐methylpyridinium), bis(3‐methylpyridinium) and bis(4‐methylpyridinium) dioxidobis(oxydiacetato)uranate(VI)

Four complexes containing the [UO₂(oda)₂]²⁻ anion (oda is oxydiacetate) are reported, namely dipyridinium dioxidobis(oxydiacetato)uranate(VI), (C₅H₆N)₂[U(C₄H₄O₅)₂O₂], (I), bis(2‐methylpyridinium) dioxidobis(oxydiacetato)uranate(VI), (C₈H₈N)₂[U(C₄H₄O₅)₂O₂], (II), bis(3‐methylpyridinium) dioxidobis(oxydiacetato)uranate(VI), (C₈H₈N)₂[U(C₄H₄O₅)₂O₂], (III), and bis(4‐methylpyridinium) dioxidobis(oxydiacetato)uranate(VI), (C₈H₈N)₂[U(C₄H₄O₅)₂O₂], (IV). The anions are achiral and are located on a mirror plane in (I) and on inversion centres in (II)–(IV). The four complexes are assembled into three‐dimensional structures via N—H...O and C—H...O interactions. Compounds (III) and (IV) are isomorphous; the [UO₂(oda)₂]²⁻ anions form a porous matrix which is nearly identical in the two structures, and the cations are located in channels formed in this matrix. Compounds (I) and (II) are very different from (III) and (IV): (I) forms a layered structure, while (II) forms ribbons.     

Synthesis,chemical and electrochemical studies of complexes of a tridentate ONS chelating ligand built around the elusive [MoVIOS]2+ core

Synthesis and characterization of four Mo(VI) complexes of a diprotic tridentate ONS chelating ligand (H₂L) containing the rather elusive [Mo^VIOS]²⁺ core is reported. These [Mo^VIOSL] complexes are obtained from their corresponding [Mo^VIO₂L] precursors using a combination of PPh₃ and PPh₃S. This process of oxo-abstraction and sulfido-inclusion affected by PPh₃–PPh₃S is reported for the first time and may be considered as a general method of converting [Mo^VIO₂L] complexes to the corresponding [Mo^VIOSL] complexes. Direct structural characterization of these complexes could not be done due to the ease of solvolysis of these oxosulfidomolybdenum(VI) complexes to the corresponding dioxomolybdenum(VI) analogues. However, the structure of these [Mo^VIOSL] complexes could be reasonably surmised from the corresponding structurally characterized [Mo^VIO₂L] complexes. Points of attachment of the potentially pentadentate but functionally tridentate ONS chelating ligands to [Mo^VIOS]²⁺ are located mainly through analysis of IR and UV-Vis spectral data and comparison with corresponding [Mo^VIO₂L] complexes of known structure. Conditions under which solvolysis of [Mo^VIOS]²⁺ to the [Mo^VIO₂]²⁺ core is significantly retarded have been identified and make us hopeful of obtaining single crystals of [Mo^VIOSL].     

Koordinationspolymere 1, 2‐Dithiooxalato‐ und 1, 2‐Dithioquadratato‐Komplexe. Synthese und Strukturen von [BaCr2(bipy)2(1, 2‐dtox)4(H2O)2], [Ni(cyclam)(1, 2‐dtsq)]·2DMF, [Ni(cyclam)Mn(1, 2‐dtsq)2(H2O)2]·2H2O und [H3O][H5O2][Cu(cyclam)]3[Cu2(1, 2‐dtsq)3]2

Coordination Polymeric 1, 2‐Dithiooxalato and 1, 2‐Dithiosquarato Complexes. Syntheses and Structures of [BaCr₂(bipy)₂(1, 2‐dtox)₄(H₂O)₂], [Ni(cyclam)(1, 2‐dtsq)]·2DMF, [Ni(cyclam)Mn(1, 2‐dtsq)₂(H₂O)₂]·2H2₂, and [H₃O][H₅O₂][Cu(cyclam)]₃[Cu₂(1, 2‐dtsq)₃]₂ 1, 2‐Dithioxalate and 1, 2‐dithiosquarate ions have a pair of soft and hard donor centers and thus are suited for the formation of coordination polymeric complexes containing soft and hard metal ions. The structures of four compounds with building blocks containing these ligands are reported: In [BaCr₂(bipy)₂(1, 2‐dtox)₄(H₂O)₂] Barium ions and pairs of Cr(bipy)(1, 2‐dtox)₂ complexes form linear chains by the bisbidentate coordination of the dithiooxalate ligands towards Ba²⁺ and Cr³⁺. In [Ni(cyclam)(1, 2‐dtsq)]·2DMF short NÖH···O hydrogen bonds link the NiS₂N₄‐octahedra with C_2v‐symmetry to an infinite chain. In [Ni(cyclam)Mn(1, 2‐dtsq)₂(H₂O)₂]·2H₂O the 1, 2‐dithiosquarato ligand shows a rare example of S‐coordination towards manganese(II). The sulfur atoms of cis‐MnO₂S₄‐polyedra are weakly coordinated towards the axial sites of square‐planar NiN₄‐centers, thus forming a zig‐zag‐chain of Mn···Ni···Mn···Ni polyhedra. [H₃O][H₅O₂][Cu (cyclam)]₃[Cu₂(1, 2‐dtsq)₃]₂ contains square planar [Cu^II(cyclam)]²⁺ ions and dinuclear [Cu^I₂(1, 2‐dtsq)₃]^4— ions. Here each copper atom is trigonally planar coordinated by S‐donor atoms of the ligands. The Cu…Cu distance is 2.861(4)Å.     

Structural Study and Solution Integrity of Dioxomolybdenum(VI) Complexes with Tridentate Schiff Base and Azole Ligands

Four new molybdenum complexes [Mo^VIO₂(L¹)(Him)] ( 1 ), [Mo^VIO₂(L¹)(3‐MepzH] ( 2 ), [Mo^VIO₂(L²)(3‐MepzH)] ( 3 ), and [(Mo^VIO₂)₂(μ‐L³)(MeOH)₂] ( 4 ) were synthesized and characterized by IR, NMR, ESI‐MS, and single‐crystal structure analysis [H₂L¹ = 2‐(salicylideneamino)‐2‐methyl‐1‐propanol, H₂L² = 2‐(3‐methoxysalicylideneamino)‐2‐methyl‐1‐propanol, H₄L³ = 1, 7‐bis(salicylidene)dihydrazide malonic acid, Him = imidazole and 3‐MepzH = 3‐methylpyrazole]. In all four structures the molybdenum atom has a distorted octahedral coordination with the three meridional donor atoms from the Schiff base di‐ or tetraanion (L^{1, 2})^2—/(L³)^4— and one oxo group occupying the sites of the equatorial plane. The other oxo group and the azole or methanol molecule occupy the apical sites. In 1—3 two centrosymmetrically related molecules form a hydrogen‐bonded pair through the (azole)N‐H···O(alkoxo) interaction. Additional crystal packing appears to be controlled mostly by π stacking between the aromatic rings of the salicyl moiety. ESI‐MS investigations reveal that the integrity of complexes 1—4 is largely retained in methanol solution. At the same time evidence is provided that di‐ to tetranuclear oligomers of formula [{Mo^VIO₂(L)}_x] and [{Mo^VIO₂(L)}_x(3‐MepzH)] with L = L¹, L², x = 2, 3, 4 are present simultaneously with 2 and 3 in methanol solution, respectively the tetranuclear species [{(Mo^VIO₂)₂(L³)}₂] with 4 .     

Dimethyl sulfoxide as an O-donor ligand in tetravalent actinide complexes

Four new perchlorate complexes of tetravalent actinides with dimethyl sulfoxide (DMSO) molecules (An⁴⁺ = Th, U, Np, Pu) are synthesized and studied. According to the X-ray diffraction data, compounds [Th(DMSO)₉](ClO₄)₄ · 2CH₃CN (I), [U(DMSO)₈](ClO₄)₄ · CH₃CN (II), [Np(DMSO)₈](ClO₄)₄ · CH₃CN (III), and [Pu(DMSO)₈](ClO₄)₄ · CH₃CN (IV) crystallize in the triclinic crystal system (space group P1). The crystals of compounds II–IV are isostructural. The absorption spectra of the complexes in the IR and visible regions are measured. All compounds exhibit a decrease in the frequencies of stretching vibrations ν(SO) over the spectrum of free DMSO, indicating the formation of the O-bonded complexes of An⁴⁺. The optical spectra of the crystalline compounds exhibit shifts of the bands of electronic f-f transitions of the An⁴⁺ ions relative to the hydrated ions: the bathochromic shifts for the U and Np complexes and the hypsochromic shift for the Pu complex. The first coordination sphere of the actinide atoms in the studied complexes is highly stable.     

Isolation of a Star‐Shaped Uranium(V/VI) Cluster from the Anaerobic Photochemical Reduction of Uranyl(VI)

Actinide oxo clusters are an important class of compounds due to their impact on actinide migration in the environment. The photolytic reduction of uranyl(VI) has potential application in catalysis and spent nuclear fuel reprocessing, but the intermediate species involved in this reduction have not yet been elucidated. Here we show that the photolysis of partially hydrated uranyl(VI) in anaerobic conditions leads to the reduction of uranyl(VI), and to the incorporation of the resulting U^V species into the stable mixed‐valent star‐shaped U^VI/U^V oxo cluster [U(UO₂)₅(μ₃‐O)₅(PhCOO)₅(Py)₇] ( 1 ). This cluster is only the second example of a U^VI/U^V cluster and the first one associating uranyl groups to a non‐uranyl(V) center. The U^V center in 1 is stable, while the reaction of uranyl(V) iodide with potassium benzoate leads to immediate disproportionation and formation of the U₁₂^IVU₄^VO₂₄ cluster {[K(Py)₂]₂[K(Py)]₂[U₁₆O₂₄(PhCOO)₂₄(Py)₂]} ( 5 ).     

Preparation,thermal and vibrational studies of [UO2(acac-o-phdn)(L)] (L=H2O,py, DMF and Et3N)

Four new dioxouranium(VI) complexes, [UO₂(acac-o-phdn)(L)] where L?=?H₂O, py, DMF and Et₃N, with the tetradentate dibasic Schiff base (acac-o-phdn), derived from condensation of acetylacetone with o-phenylene diamine have been synthesized. The infrared spectra were obtained and full assignments of all the observed vibrations are proposed on the basis of C_2v symmetry for H₂O and py complexes and C_s for the other two complexes, respectively. The bond stretching force constant and bond length of the U=O bond for the four complexes were calculated. Differential thermal analysis (DTA) and thermogravimetric (TG) analysis of the complexes were also carried out.     

Ligand Exchange in Pd(II)-NaCl-H<Subscript>2</Subscript>O and Pd(II)-HCl-H<Subscript>2</Subscript>O Systems: Quantum-Chemical Consideration

The behavior of potassium tetrachloropalladate(II) in media simulating biological liquids is studied. The rate of aquation in aqueous NaCl solutions is shown to be higher than the rate at which the Cl^? ligand enters the inner coordination sphere of the Pd atom. In HCl solutions, the formation of the Pd chloro complexes predominates due to protonation of water molecules in the composition of aqua complexes. The reactions of replacement of the ligands (H₂O molecules and H₃O⁺ ion) in the planar Pd(II) complexes by the chloride ion are studied by the ZINDO/1 method. All the complexes containing H₂O and H₃O⁺ ligands, except for [Pd(H₂O)₄]²⁺, contain intramolecular hydrogen bonds. The ZINDO/1 and RHF/STO-6G(d) calculations revealed “nonclassic” symmetrical O? H?O hydrogen bond in the [[Pd(H₂O)₃(H₃O)]³⁺ and trans-[Pd(H₂O)₂(H₃O)Cl]²⁺ complexes. The replacement of the H₃O⁺ ion by the Cl^? ion at the first three steps is thermodynamically more advantageous than the displacement of water molecules from the metal coordination sphere. The logarithms of stepwise stability constants of Pd(II) chloro complexes are found to correlate linearly with the enthalpies (ZINDO/1, PM3) of reactions of H₂O replacement by Cl^?.     

Thermal decomposition of Np(IV) and Pu(III, IV) oxalates

Thermal decomposition of Pu(C₂O₄)₂·6H₂O, Pu₂(C₂O₄)₃·10H₂O and Np(C₂O₄)₂ ·6H₂O has been studied by using combination of gas chromatography, infrared spectroscopy, spectrophotometry and complex thermal analysis. We also investigated the decomposition of Pu oxalate under its -radiation. The reduction of Pu(IV) to Pu(III) has been confirmed. We found Np(V), which is formed from Np(IV), on the basis of infrared and absorption spectra of the intermediate compounds.     

Infrared vibrational spectra,electronic structures,and formation reactions of polypyrrolic mono‐ and bis‐actinyl complexes: A relativistic DFT study

The development of synthetic techniques has enabled synthesis and characterization of a series of mono and bis‐uranyl complexes of octadentate polypyrrolic macrocycles such as aryl‐lined H₄L^Ar and anthracenyl‐linked H₄L, which is complemented by theoretical investigation via extending to more toxic and radioactive transuranics. The relativistic density functional theory (DFT) study has been dedicated to twelve actinyl complexes supported by the H₄L ligand. The actinides include U, Np, and Pu elements, and either one or two is rendered in complexes with oxidation states of V or VI. Calculated symmetric/asymmetric An = O stretching vibrational frequencies show the decreasing trend along U, Np, and Pu, which is consistent with calculated bond orders. The hydrogen bonds between –yl endo‐oxo and remaining hydrogen atoms of pyrrolides in mononuclear complexes cause pronounced redshift of An = O vibrational frequencies compared to those in binuclear complexes, so does the reduction from hexa‐ to penta valent complexes. The electronic structures of actinyl complexes were calculated. For example, B‐ pyU^VI possesses low‐lying U(5f )‐character virtual orbitals, where f (δ) and f (?) orbitals occur in low‐energy region and π‐type ones are residing further high; the σ*(U = O) and σ(U = O) orbitals are significantly split over 7 eV. The previous experimental observation that the 1:1 reactions between uranyl salts and the macrocycle tend to give a mixture of bis‐ and mono‐uranyl complexes, with bis‐ the major product, has been corroborated by computational studies of the thermodynamics of the reactions.     

Reactions of tungsten(VI) and molybdenum(V) chlorides,and tungsten(VI) and molybdenum(VI) oxychlorides,with azoxybenzene

Reactions of W^VI and Mo^V chlorides with azoxybenzene yield ionic species of W^VI and Mo^VI oxychlorides in which the cation is a protonated azobenzene. The reaction between MoCl₅ or MoOCl₄ and azoxybenzene gives, after extraction with methylene chloride—ethanol mixture, the complex [trans-MoOCl₄(OC₂H₅)]^? [C₁₂H₁₀N₂H]⁺. In contrast, WOCl₄ reacts with azoxybenzene to give a stable non-ionic adduct in which the organic moiety is coordinated through its oxygen atom trans to the WO bond. Several complexes of substituted azoxybenzene having similar structures are described.