New preparations and molecular structures of cis-MCl2(Ph2PCH2PPh2)2, M = Ru,Os and trans-RuCl2(Ph2PCH2PPh2)2

The title compounds were made by reacting bis(diphenylphosphino)methane (dppm) with reduced solutions of OsCl₆^4? and Ru₂OCl₁₀^4?. The crystal and molecular structures of these compounds have been determined form three-dimensional X-ray study. The cis-isomers crystallize with one CHCl₃ per molecule of the complex. All three compounds crystallize in the monoclinic space group P2₁/n with unit cell dimensions as follows: Cis-OsCl₂(dppm)₂·CHCl₃: a = 13.415(4) Å, b = 22.859(4) Å, c = 16.693(3) Å, β = 105.77(3)°, V = 4926(3) ų, Z = 4. cis-RuCl₂(dppm)₂·CHCl₃: a = 13.442(3) Å, b = 22.833(7) Å, c = 16.750(4) Å, β = 105.53(2)°, V = 4953(3) ų, Z = 4. trans-RuCl₂(dppm)₂: a = 11.368(7) Å, b = 10.656(6) Å, c = 18.832(12) Å; β = 103.90(6)°, V = 2213(7) ų; Z = 2. The structures were refined to R = 0.044 (R_w = 0.055) for cis-OsCl₂(dppm)₂·CHCl₃; R = 0.065 (R_w = 0.079) for cis-RuCl₂(dppm)₂·CHCl₃ and R = 0.028 (R_w = 0.038) for trans-RuCl₂(dppm)₂. The complexes are six coordinate with stable four-membered chelate rings. The PMP angle in the chelate rings is ca. 71° in each case.     

Regulations of macrophage-mediated tumor cell killing by prostaglandins: Comparison of the effects of PGE2 and PGI2

Mouse resident peritoneal macrophages stimulated by purified bacterial lipopolysaccharide (LPS) produced both prostaglandin E₂ (PGE₂) and prostaglandin I₂ (PGI₂), the latter detected as its stable metabolite, 6-keto PGF_1α. Maximum production, induced in each case by 1 ng/ml purified LPS, was in the range of 10⁻⁷M for PGI₂ and 3 × 10⁻⁸M for PGE₂. A quantitatively similar increase in intracellular levels of macrophage cyclic AMP (measured on a whole cell basis), with a similar duration of effect, was stimulated by PGE₂ and PGI₂; however, only PGE₂ had a negative regulatory effect on macrophage activation for tumor cell killing. These data confirm that more than a whole cell increase in the concentration of cyclic AMP is needed to shut off nonspecific tumor cell killing mediated by LPS-activated resident peritoneal macrophages.     

Differential effects of prazosin and rauwolsin on the release of prostaglandins I2 and E2 from the perfused mesenteric arterial bed of the rabbit following nerve stimulation

Sympathetic nerve stimulation of the perfused mesenteric arterial bed of the rabbit, , increase the secretion of prostaglandin (PG)I₂ and PGE₂. Prazosin (4.8 × 10⁻⁶), and α₁ adrenergic receptor antagonist, inhibited this inrease in release of PGI₂ but not of PGE₂ whereas rauwolsin (10⁻⁷ M), an α₂ adrenergic receptor antagonist, inhibited the increase in release of PGE₂ but not of PGI₂. Prazosin (10⁻⁶ M) completely blocked the vasoconstrictor response to nerve stimulation, and to norepinephrine and phenylephrine administration, suggesting there to be little of an α₂ adrenergic receptor component in this response. It is concluded that the increase in PGI₂ release follows the activation of α₁ adrenergic receptors and is therefore post-junctional in origin, whereas the increase in PGE₂ release follows the activation of α₂ adrenergic receptors and may be pre- and/or post-junctional in origin.Indomethacin (2.8 × 10⁻⁷, 5.6 × 10⁻⁷ and 1.12 × 10^{−6 M} did not affect the vasoconstrictor responses to nerve stimulation at 10 Hz, whereas rauwolsin (10⁻⁷ M) in the presence of indomethacin substantially increased them. These results indicate that PGE₂ does not regulate norepinephrine release following nerve stimulation at 10 Hz to rabbit mesenteric arteries, and that the inhibition of norepinephrine release following stimulation of α₂ pre-junctional receptors is independent of PG involvement.     

Synthesis and crystal structure of bis(tetramethylammonium) aquotetra-fluorodioxouranate(VI) dihydrate, [(CI3)4 N]2[UO2 F4(H2 O)]·2H2O

The title compound has been synthesized and subjected to crystal structure analysis. M_r = 548.50, m.p. 108.1 °C (decom.), orthorhombic, Im2m,a = 7.006(2), b = 8.938(2), c = 13.619(2) Å V = 852.8(3) ų, Z = 2, D_x = 2.136, D_m, (flotation in CCl₄/CH₂I₂) = 2.128 g cm^?3, λ(Mo-Kα) = 0.71069 Å, μ = 90.79 cm^?1, F(000) = 519.89, T = 295 K, final R_F = 0.036 and R_G = 0.044 for 566 observed reflections. The discrete [UO₂F₄(H₂0)]^2? anion has site symmetry m2m, its virtually linear uranyl moiety being surrounded by fluoro and aquo ligands occupying the vertices of a pentagon in the equatorial plane. Watet molecules serve to link the complex anions by hydrogen bonds into layers, between which the organic cations are accommodated.     

Coordination chemistry of lanthanides with cryptands. An X-ray and spectroscopic study of the complex Nd2(NO3)6 [C18H36O6N2]·H2O

By reacting neodymium nitrate hexahydrate with the cryptand 〈222〉 in methanol, the complex Nd₂-(NO₃)₆[C₁₈H₃₆O₆N₂]·H₂O was obtained and analyzed by single-crystal X-ray diffraction. The cell is triclinic P$\text{1}$ with a = 14.870(2) Å, b = 13.261(2) Å, c = 8.832(1) Å, α = 91.2(1)°, β = 93.4(1)°, γ = 87.6(1)°, Z = 2 and U = 1736.6 ų. The structure was refined by least-squares methods to the conventional R = 0.039 for 6177 observed reflections. The compound contains the cations [Nd〈222〉(NO₃)]²⁺ and the anions [Nd(NO₃)₅·H₂O]^2?, and is isostructural with the samarium analogue. Solid state fluorescence spectra of the title complex were measured at room and liquid nitrogen temperature, and the transitions ⁴F_3/2 → ⁴I_9/2 and ⁴F_3/2 → ⁴I_11/2 analyzed.     

X-ray crystal Structure of [1,2-bis(diphenylphosphino)ethane]bis(3,5-dimethylpyrazole-N)platinum(II) tetrafluoroborate dichloromethane solvate, [(Ph2PCH2CH2PPh2)Pt(3,4-Me2pzH)2][BF4]2·CH2Cl2

The crystal structure of the compound [(Ph₂PCH₂CH₂PPh₂)Pt(3,5-Me₂pzH)₂][BF₄]₂·CH₂Cl₂ has shown that the ligands around the Pt atom are approximately in a square planar coordination, whereas the pyrazole rings point roughly in the same direction, away from the coordination plane. This unusual conformation is probably due to the hydrogen bonds with fluorine atoms of the BF₄^? anion. Bond distances and angles are compared with those in other pyrazole complexes.     

Synthesis and characterization of uranyl(VI) and thorium(IV) complexes with phosphine oxides. The crystal structure of UO2(NO3)2(NO2-C6H4Ph2PO)2

Uranyl(VI) and thorium(IV) complexes of the type UO₂(NO₃)₂(L¹)₂, UO₂(NO₃)₂(L²)₂, UO₂(CH₃COO)₂L¹, UO₂(CH₃COO)₂L², Th(NO₃)₄(L¹)₂ and Th(NO₃)₄(L²)₂ (L¹ = (2-nitro)phenyl-bis-phenyl phosphine oxide, L² = triferrocenylphosphine oxide) are reported, together with their physico-chemical properties.The crystal structure of UO₂(NO₃)₂(L¹)₂ is also reported. The crystals are monoclinic, space group P2₁/n with a = 17.78(1), b = 13.88(1), c = 17.37(1) Å, β = 114.8(1)° for Z = 4. The uranium atom is 8-coordinated, the uranyl(VI) group being equatorially surrounded by an irregular hexagon of six oxygen atoms from two trans neutral ligands and two nitrato groups.     

Characterization of brain D2 dopamine receptors

In order to characterize and partially purify solubilized dopamine receptors, canine brain striatum microsomes were solubilized with 1% digitonin, and enriched by either gel permeation chromatography, preparative vertical column isoelectric focusing, or sucrose gradient ultracentrifugation. Chromatography on Sephacryl S-300 in buffer (contaning 0.05% Triton X-100) yielded a Stokes radius of 5.8 nm. Isoelectric focusing of the solubilized, radiolabelled receptor produced peaks of [³H]spiperone radioactivity corresponding to isoelectric values of 5.0 and 7.8, of which the former has been shown elsewhere to be the intact D₂ dopamine receptor. Sucrose density gradient ultracentrifugation, again in buffer containing 0.05% Triton X-100, indicated a hydrodynamic mol. wt of 136,000 Daltons, which corresponds closely to the value of 123,000 Daltons estimated using radiation inactivation. Such molecular characterization will aid in the distinction of dopamine receptor subtypes.     

Molecular conformation of prostaglandin E2

The crystal and molecular structure of prostaglandin E₂ (PGE₂) has been determined by X-ray diffraction. The compound crystallizes in the triclinic space group P1 with Z = 1 and , , , α = 87.347°, β = 94.042°, and γ = 91.010°. Gauche-gauche interactions appear in both side chains. The efficient molecular packing and hydrogen bonding network appears to stabilize the observed molecular conformation.     

Crystal structure of nonaquasamarium(III)bromide-l,4-dioxan adduct (1:3:2), Sm(H2O)9·Br3(C4H8O2)2

The title compound has been found to consist of tricapped trigonal prismatic Sm(H₂O)₉³⁺ ions in C_2v symmetry, sandwiched between expanded ‘close packed’ layers of bromide ions, with 1,4-dioxan molecules in chair conformation hydrogen bonding between the equatorial water molecules of adjacent cations.Orthorhombic, Amm2, a = 8.010(3), b = 19.848(4), c = 7.388(3) Å, R = 0.022 for 992 unique reflexions.     

An inspection into the class of bis(alkyne)-undecacarbonyl-quadro-tetraruthenium complexes. Crystal structure and dynamic behaviour of Ru4(CO)11 (μ4, η2-MeC2Ph)2

The reactions of the butterfly complex Ru₄(CO)₁₂(MeC₂Ph) with several alkynes give the quasiplanar derivatives Ru₄(CO)₁₁(MeC₂Ph)(Alkyne) in almost quantitative yields.The structure of Ru₄(CO)₁₁(MeC₂Ph)₂ has been determined by X-ray methods. Crystals are monoclinic, space group C2/c, with Z = 4 in a unit cell of dimensions a 22.383(16), b 9.048(8), c 18.268(12) Å, β = 127.25(4)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.034 for 1420 observed reflections. The complex, having an imposed C₂ symmetry, presents a tetranuclear metal cluster in which the Ru atoms are in a tetrahedrally-distorted square arrangement. Ten carbonyls are terminal and one symmetrically bridges an edge of the cluster. Each of the two alkyne ligands is σ-bonded to two Ru atoms on the opposite vertices of the cluster and π-bonded to the other two. The organometallic cluster has a Ru₄C₄ core in which the metal and carbon atoms occupy the vertices of a triangulated dodecahedron.     

Metal complexes of virus inhibitors. Part III. Coordination properties of 1-n-propyl-2-α-hydroxybenzylbenzimidazole and the X-ray crystal structure of Ni(C17H18N2O)2(C17H17N2O)1(ClO4)1

Complexes are described of Cobalt(II) and Nickel- (II) salts with the title ligand L. The X-ray crystal structure is described of NiL₂L′₁(ClO₄)₁. One ligand molecule (L′) in this complex is deprotonated and the structure involves strongly hydrogen bonded dimers with OHO bonds = 2.56 Å and 2.62 Å and a NiNi bond = 4.77 Å. The corresponding Cobalt complex is thought to be similar but no other compounds containing L′ were obtained.     

The quasi-relativistic Xα-SW molecular orbital method in organo-f-element chemistry: applications to UCl4, (η5-C5H5)4U and (η5-C5H5)2UCl2

The advantages and disadvantages of using the Xα scattered-wave molecular orbital method with quasi-relativistic corrections for the calculation of the electronic structure of organo-f-element compounds is discussed. Application of the method in organouranium chemistry is discussed via comparative calculations on UCl₄, (η⁵-C₅H₅)₄U, and (η⁵-C₅H₅)₂UCl₂. It is found that the η⁵-C₅H₅^? ligand is a better donor to U than is Cl^? and that the valence orbitals of (η⁵-C₅H₅)₂UCl₂ are energetically closer to those of (η⁵-C₅H₅)₄U than UCl₄. The calculational results are in excellent accord with experimental photoelectron spectroscopic studies.