Chloride and oxinate mixed complexes of uranium(IV) and thorium(IV)

Some new chloride and oxinate mixed complexes of general composition MCl_4?nOx_n (M = U(IV) and Th(IV); Ox = 8-hydroxyquinolinato; n = 1, 2) were synthesized by the reaction of uranium or thorium tetrachlorides with M′Ox (M′ = Na, K, Tl) or MgOx₂. By using the oxine the formation of the adducts MCl₄·2HOx occurs, without the substitution of the chloride ions. By suspending MCl₄·2HOx in the presence of a strong base (Proton Sponge) MCl₂Ox₂ was formed immediately. The reaction of UCl₂Ox₂ and TlCp did not afford Cp₂UOx₂, which can be easily prepared by reaction of Cp₂U(NEt₂)₂ and HOx.     

N,N-diisopropylcarboxylic acid amide complexes of thorium(IV) and uranium(IV) N-thiocyanates; the crystal structure of tetraisothiocyanato tetrakis(N,N-diisopropylacetamide-O)uranium(IV)

The complexes M(NCS)₄·xL (x = 2, M = U, L = Me₃CCON(Prⁱ)₂(dippva); x = 3, M = Th, L = Me₂CHCON(Prⁱ)₂(dipiba) and dippva, M = U, L = EtCON(Pr¹)₂(dippa), dipiba and dippva; x = 4, M = Th, L = MeCON(Prⁱ)₂(dipa), dippa and dipiba, M = U, L = dipa, dippa) and the solvates M(NCS)₄·4dipa·CH₂Cl₂ (M = Th, U) have been prepared. Their i.r. and u.v.-visible (M = U only) spectra are reported. The crystal and molecular structure of U(NCS)₄(dipa)₄· CH₂Cl₂ has been determined by the heavy-atom method from X-ray diffractometer data and refined by least squares to R 0.029 for 1135 independent reflections. The crystal is tetragonal, space group P$\text{4}$2₁c, with Z = 2, a = 15.663(4) and c = 10.512(3) Å. The coordination geometry about the 8-coordinate uranium atom is dodecahedral with the N atoms of the NCS groups occupying the dodecahedral A sites and the ‘dipa’ O atoms the B sites. The bonding distances of UO and UN are 2.363(8), and 2.444(11) Å respectively.     

Some new derivatives of organozirconium(IV) and organotitanium(IV) with thiophenecarboxylic acids

The complexes of the type Cp₂M(3-TC)Cl, Cp₂M(3-TC)₂, Cp₂M(3-TA)Cl, Cp₂M(3-TA)₂, Cp₂M(2-TB)Cl, Cp₂M(2-TB)₂ [where Cp = cyclopentadienyl, M = Zr or Ti] were synthesized by the reactions of dichlorobis(cyclopentadienyl)zirconium(IV) and dichlorobis(cyclopentadienyl)titanium(IV) with 3-thiophenecarboxylic acid (3-TCH), 3-thiopheneacetic acid (3-TAH) and 2-thiophenebutyric acid (2-TBH) respectively in different stoichiometric ratios. The new complexes were characterized by their elemental analysis, ¹H NMR, IR, and electronic spectral data.     

Syntheses of new uranium complexes Cl2U(π-S4N4 and (C5H5)3UClAlCl3·THF

The new bridging complexes Cp₃UClClAlCl₂ and Cp₃UClClAlCl₂·THF were synthesized by reaction of triscyclopentadienyl uranium chloride with aluminum trichloride in the presence of different solvents. The Cp₃UClClAlCl₂·THF complex id proposed to have a square bipyramidal structure with THF occupying the sixth position. A new inorganic cyclooctatetraene uranium complex, UCl₂(S₄N₄), was also synthesized by uranium tetrachloride with tetrasulfur tetranitride.     

Parallel activation of cyclic AMP phosphodiesterase and cyclic AMP-dependent protein kinase in two human gut adenocarcinoma cells (HT 29 and HRT 18) in culture,by vasoactive intestinal peptide (VIP) and other effectors activating the cyclic AMP system

Vasoactive intestinal peptide (VIP), secretin, catecholamines and prostaglandin E₁ (PGE₁) in the presence of a cyclic nucleotide phosphodiesterase inhibitor stimulate the accumulation of cyclic AMP in two colorectal carcinoma cell lines (HT 29 and HRT 18) with subsequent activation of the cyclic AMP-dependent protein kinases. In HT 29 cells incubated without phosphodiesterase inhibitor, 10^?9 M VIP promotes a rapid and specific activation of the low $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ cyclic AMP phosphodiesterase (1.7-fold); at 25°C the effect is maintained for more than 15 min, while at 37°C the activity returns to basal value within 15 min. As shown by dose-response studies, VIP is by far the most effective inducer ($\text{K}{}_{\mathrm{<mtext>a</mtext>}}\text{= 4 · 10}{}^{\mathrm{?10}}\text{M}$) of the cyclic AMP phosphodiesterase activity; partial activation of the enzyme is obtained by 3 · 10^?7 M secretin, 10^?5 M isoproterenol and 10^?5 M PGE₁; PGE₂ and epinephrine are without effect. In HRT 18 cells VIP is less active ($\text{K}{}_{\mathrm{<mtext>a</mtext>}}\text{= 2 · 10}{}^{\mathrm{?9}}\text{M}$) whereas 10^?6 M PGE₁, 10^?6 M PGE₂ and 10^?5 M epinephrine are potent inducers of the phosphodiesterase activity. The positive cell response to dibutyryl-cyclic AMP further indicates that cyclic AMP is a mediator in the phosphodiesterase activation process. The incubation kinetics and dose response effects of the various agonists on the cyclic AMP-dependent protein kinase activity determined for both cell types in the same conditions show a striking similarity to those of phosphodiesterase. Thus coordinate regulation of both enzymes by cyclic AMP was observed in all incubation conditions.     

The enzyme "aldehyde oxidase" is an iminium oxidase. Reaction with nicotine delta 1'(5') iminium ion.

The second of the two reaction steps involved in the metabolic transformation of (?)-nicotine to (?)-cotinine $\text{(}\text{3}\text{) (}\text{i.}\text{e.}$, the oxidation of the intermediate $\text{2}\text{)}$ is mediated mainly, if not solely, by the enzyme aldehyde oxidase (EC 1.2.3.1). Of the molecular species that constitute $\text{2}$, nicotine Δ^1′(5′) iminium ion $\text{(}\text{2a}\text{)}$ appears to serve as the substrate. The enzyme has a strong affinity for $\text{2a}$, as shown in a study on the inhibition of the oxidation of 3-(aminocarbonyl)-1-methylpyridinium chloride. This study gave a value of K_i = 6 μM; K_m = 2 μM (pH 7.4). Mainly in view of this finding, “iminium oxidase” seems to be a more adequate name than “aldehyde oxidase” for this enzyme.     

Spectroscopy and crystal structure of neodymium coordination compound with glycine: Nd2(Gly)6·(ClO4)6·9H2O

Neodymium complex compound with glycine: Nd₂(Gly)₆·(ClO₄₆·9H₂O was synthesized and obtained in the form of monocrystals. Absorption spectra recorded in the region of 8000–35 000 cm^-1 were measured along the crystallographic axes. Intensities of the f-f transitions were analysed on the basis of the Judd theory. The X-ray crystal structure determination of the complex is reported. Crystals are triclinic, space group P$\text{I}$, with a = 11.554(4) Å, b = 14.108(1) Å, c = 15.660(3) Å, α = 97.14(1)°, β = 102.82(2)°, γ = 105.28(1)°, V = 2355.25 ų Z = 2, M.W. = 1495.4, D_c = 2.129)(3) g cm^-3, D^m = 2.103(1) g cm^-3. The structure was solved by Patterson's method and successive Fourier syntheses giving the locations of all nonhydrogen atoms. The final R factor was 0.062 and R_w = 0.073 for 12869 reflections with |F_o| > 5σ|(F_o)|. The asymmetric unit consists of a dimeric formula unit. The coordination polyhedron of Nd atoms comprises seven oxygen atoms from glycine and two from water molecules. The neodymium-glycine bonding mode is compared with that of the calcium-glycine complex.     

N-substituted ethylcarbamate complexes of thorium(IV) and lanthanum(III) nitrates

N-substituted ethylcarbamates form with thorium nitrate the complexes Th(NO₃)₄·3RHNC(O)OC₂H₅ (where R = CH₃, C₂H₅, C₆H₅(CH₃)CH) and with lanthanum nitrate the complexes La(NO₃)₃· 2RR′NC(O)OC₂H₅·3H₂O (where R = CH₃, C₂H₅, C₆H₅(CH₃)CH; R′ = H and R = CH₃, C₆H₅; R′ = C₂H₅ or R = R′ = CH₃). In addition the anhydrous La(NO₃)₃·3(C₂H₅)₂NC(O)OC₂H₅ has been isolated. From the IR spectra it is deduced that the carbamates coordinate the metal through the carbonyl oxygen atom and that the nitrato groups act as chelated ligands. ¹H nmr spectral data of the complexes are reported and discussed.     

Preliminary crystallographic data for Azotobacter cytochrome c5.

Two closely related crystal forms of dimeric cytochrome c₅ from Azotobacter rinelandii have been grown. The crystals belong to space groups (C2 with $\text{a = 45·0, b = 38·4, c = 41·3}\text{A}\text{?}\text{and}\text{β = 101 ° 0′}$; and C1 (a centered triclinic cell) with $\text{a = 46·0, b = 37·6, c = 49·4}\text{A}\text{?}$, α = 87 ° 20′, β = 96 ° 40′ and γ = 90 ° 0′. In C2 the 24,000 molecular weight dimer lies on a Crystallographic 2-fold axis; in C1 the entire dimer occupies the asymmetric unit.     

Experimental access to the molecular and electronic structures of organo-f-element complexes by NMR spectroscopy

The main objective of this survey is to demonstrate that by extensive assessment of variable temperature ¹H NMR data obtained on paramagnetic f-element complexes in solution, not only valuable information on details of the molecular structure, but also on the electronic structure may be deduced. One of the most informative quantities to arrive at is the paramagnetic anisotropy term, χ∥ - χ⊥, of axially symmetric molecules from which, if the bulk susceptibility $\text{χ}$ is also known, the crystal-field sensitive parameters χ∥ and χ⊥ can be derived.The majority of the examples considered belong to the widely studied type [Cp₃^fML_n]^q (Cp = η⁵C₅H₄R); ^fM = Pr(III), Nd(III), Yb(III) and U(IV); n = 0, 1 and 2; q = 0 or ?1) and to the uranocene family. The survey also includes the two sub-classes of novel anionic complexes [Cp₃LnL]^? and [(Cp₃Ln)₂(μ-L)]^?, respectively, and different isomers of the general composition [Cp₃UXY]^q (L = lanthanoid).     

Crystallization and preliminary crystallographic data for cytochrome c551.5 (c7) from Desulfuromonas acetoxidans.

Cytochrome c₇, a low potential, three heme-containing protein (molecular weight 9800) was isolated from Desulfuromonas acetoxidans and crystallized from polyethylene glycol solutions. The crystals belong to the orthorhombic space group P2₁2₁2₁, with unit-cell dimensions $\text{a = 44·10}\text{A}\text{?}\text{, b = 37·55}\text{A}\text{?}$ and $\text{c = 45·08}\text{A}\text{?}$ and have one molecule of protein per asymmetric unit.     

Uranium(III) poly(pyrazol-1-yl)borate complexes

Reactions of the adduct UCl₃·(THF)_x (THF = tetrahydrofuran) with compounds of the type K[H_nBL_4?n], where L = pyrazole or 3,5-dimethylpyrazole, are presented. Based on the results obtained the two compounds UCl₂H₂BPz₂·THF and UCl₂HBPz₃·THF were isolated.     

Specific platinum chelation by the guanines of the deoxyhexanucleotide d(T-G-G-C-C-A) upon reaction with cis-[Pt(NH3)2(H2O)2](NO3)2

The stoichiometric reaction between d-TpGpGpCpCpA (d(T-G-G-C-C-A)) and $\text{cis}$-[Pt(NH₃)₂(H₂O)₂](NO₃)₂ (8.4 × 10^?6 to 1.3 × 10^?4M in water at pH 5.5–6) gives a single complex. High pressure gel permeation chromatography and pH-dependent ¹H NMR analyses of the nonexchangeable base protons, show that it is a platinum chelate with the $\text{cis}$-Pt^II(NH₃)₂ moiety bound to the two N7 atoms of the adjacent guanines. A 3 × 10^?3M reaction gives the same platinum chelate, via the formation of intermediate complexes, together with unsoluble adducts.     

Some coordination compounds of titanium and zirconium halides with tertiary phosphines and related ligands

Various new adducts of TiCl₄, (PhO)₂TiCl₂, TiCl₃ and ZrCl₄ with phosphine and amine ligands are reported including, (PhO)₂TiCl₂·2L (or L′) (L = PMe₃, PPh₃; L′ = dmpe, dbpe, tmed); MCl₄·L (M = Ti, Zr; L = dbpe): TiCl₃·L (L = dmpe, dbpe, tmed): TiCl₃·tmed·THF and ZrCl₄·1.5tmed. The solution properties of some of the TiCl₄ adducts are discussed, as deduced from ³¹P NMR spectra.     

Preliminary crystallographic data for cross-linked (lysine7-lysine41)-ribonuclease A

A cross-linked derivative of ribonuclease A, N^ε,N^ε′-(2,4-dinitrophenylene-1,5)-(lysine⁷-lysine⁴¹)-RNase A, has been crystallized by dialysis against 30% ($\text{v}\text{v}$) ethanol/water mixtures buffered at high pH. Single crystals belong to the orthorhombic space group P2₁2₁2₁, $\text{a = 37.2}\text{A}\text{?}\text{, b = 41.2}\text{A}\text{?}\text{, b = 41.2}\text{A}\text{?}$, with one molecule in the Crystallographic asymmetric unit.