Organometallic Chemistry of Diphosphazanes. 11. Reactions of fac-[Mo(CO)3(MeCN){.eta.2-Ph2PN(Pri)PPh(DMP)}] (DMP = 3,5-Dimethyl-1-Pyrazolyl) with Diphosphazanes and Diphosphinoalkanes and Oxidative Addition with Iodine

The use of fac-[Mo(CO)(3)(MeCN)(eta(2)-L(1))] (1a) {L(1) = Ph(2)PN(Pr-i)PPh(DMP)}(2) as a precursor to metalloligands and bimetallic, heterotrimetallic, and heptacoordinated complexes is reported. The reaction of 1a with diphosphazane, dppa, or a diphosphinoalkane such as dppm or dppe yields the fac-eta(1)-diphosphine substituted metalloligands, fac-[Mo(CO)(3)(eta(2)-L(1))(eta(1)-PXP)] {PXP = dppa (2), dppm (3), and dppe (4)}. These undergo isomerization to yield the corresponding mer-diphosphine complexes (5-7). Oxidation of the uncoordinated phosphorus atom of the mer-eta(1)-dppm-substituted complex eventually provides mer-[Mo(CO)(3)-(eta(2)-L(1)){eta(1)-Ph(2)PCH(2)P(O)Ph(2)}](8). The structure of the latter complex has been confirmed by single crystal X-ray diffraction {triclinic system, P ($) over bar 1; a = 11.994(3), b = 14.807(2), c = 15.855(3) Angstrom; alpha = 114.24(1), beta = 91.35(2), and gamma = 98.95(1)degrees; Z = 2, 4014 data (F-0 > 5 sigma(F-0)), R = 0.066, R(W) = 0.069}. Treatment of the dppe metalloligand 7 with [PtCl2(COD)] yields the heterotrimetallic complex cis-[PtCl2{mer-[Mo(CO)(3)(eta(2)-L(1))(eta(1)-dppe]}(2)] (9). Attempts to prepare a related trimetallic complex with the dppm-containing metalloligand were unsuccessful; only the tetracarbonyl complex cis-[Mo(CO)(4)(eta(2)-L(1))] (1b) and cis-[PtCl2(eta(2)-dppm)] were obtained. Reaction of la with dppe in the ratio 2:1 yields the mer-mer dinuclear complex [{mer-[Mo(CO)(3)(eta(2)-L(1))]}(2)(mu-dppe)] (10) bridged by dppe. Oxidation of 1a with iodine yields the Mo(II) heptacoordinated complex [MoI2(CO)(2)(eta(3)-L(1))] (11) with tridentate PPN coordination. The same Mo(II) complex 11 is also obtained by the direct oxidation of the tetracarbonyl complex cis-[Mo(CO)(4)(eta(2)-L(1))] (1b) with iodine. The structure of 11 has been confirmed by X-ray diffraction studies {monoclinic system, Cc; a = 10.471(2), b = 19.305(3), c = 17.325(3) Angstrom; beta = 95.47(2)degrees; Z = 4, 3153 data (F-0 > 5 sigma(F-0)), R = 0.049, R(W) = 0.051}. This complex exhibits an unusual capped-trigonal prismatic geometry around the metal. A similar heptacoordinated complex 12 with a chiral diphosphazane ligand {L(3) = (S,R)-P(h)2PN-(*CHMePh)*PPh(DMP)} has also been synthesized.

Marine Mammal Strandings in the United States: Proceedings of the Second Marine Mammal Stranding Workshop, Miami, Florida, December 3-5, 1987

Over a decade ago, in August 1977, the First Marine Mammal Stranding Workshop was convened in Athens, Georgia. That workshop, organized by j.R. Geraci and D.J. St. Aubin, not only considered biology and pathology of stranded marine mammals, but it also served as a springboard for the formation of regional marine mammal stranding networks in the United States. The ramifications have been extremely important to the field of marine mammalogy since, for some species, examination or rehabilitation of stranded specimens serves as virtually the only source of information on distribution, anatomy, physiology, reproduction, and pathology. The First Marine Mammal Stranding Workshop led to increased awareness of the marine mammals themselves, as well as the logistic and legal factors associated with effective handling of the animals. A number of individuals indicated that they felt that a Second Marine Mammal Stranding Workshop held prior to the Seventh Biennial Conference on the Biology of Marine Mammals (Miami, Florida; December 1987) would be both timely and productive. Accordingly, we organized the workshop and scheduled it to occur on 3-5 December. Our goals for the workshop were several, including 1) providing descriptions of some research, especially new techniques, regarding stranded marine mammals; 2) providing a forum where scientists could interact and possibly initiate cooperative research activities; 3) presenting information regarding procedures used effectively to handle stranded animals; 4) assessing ways to standardize data and specimen collection, archiving, and retrieval; and 5) providing a forum for assessing accomplishments and status of regional stranding networks to date, as well as for making recommendations regarding future activities of the networks. Nearly 100 individuals representing Federal and State governments, academic institutions, the oceanarium industry, consulting groups, conservation organizations, and the private sector attended the workshop (see Workshop Participants, this volume). (PDF file contains 166 pages.)

三苯基锡-2-(1,2-亚乙二硫)亚甲基-3-羰基-5-芳基-4-戊烯酸酯的合成及晶体结构

由2-(1,2-亚乙二硫)亚甲基-3-羰基-5-芳基-4-戊烯酸与三苯基氢氧化锡反应,合成了九个标题化合物3.用X射线衍射法测定了3b的晶体结构.该晶体属三斜晶系,空间群Pl,α=0.9074(2)nm,b=1.6809(3)nm,c=2.1834(4)nm,α=77.57(3)°,β=88.04(3)°,γ=89.47(3)°,V=3.2503nm~3,Z=2;R=0.0592.由锡氧原子间距离可推测,该晶体中羧酸根作为双齿配体与锡原子形成了分子内五配位结构.

Electrochemical impedance spectroscopy analysis for oxygen reduction reaction in 3.5% NaCl solution

The electrochemical impedance spectroscopy (EIS) at different potentials has been used to study the oxygen reduction reaction (ORR) in 3.5% NaCl solution on glassy carbon (GC) electrode in this work. Results show that ORR consists of three two-electron reaction steps and both superoxide ion (O-2(-)) and hydrogen peroxide (H2O2), which are produced by ORR, obstruct the diffusion of oxygen to the surface of the electrode and make the EIS results change into a transmissive finite diffusion process with the real part contraction and a reflective finite diffusion process from a semi-infinite diffusion process. The values of electron transfer resistance (R-t) and diffusion resistance (R-d) were calculated from EIS. O-2(-) influenced strongly on the Rt values and induced a maximum at -0.45 V.

Low temperature X-ray structures of two crystalline forms (I) and (II) of the pyrimidine derivative and sodium channel blocker BW1003C87: 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine

The X-ray crystal structures of two crystalline forms of 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine, C10H7Cl3N4 (code name BW1003C87) (I) and (II), have been carried out at liquid nitrogen temperature. A detailed comparison of the two structures is given. Both are centrosymmetric, with structure (I) in the triclinic space group P (1) over bar unit cell a = 6.4870(10), b = 9.216(2), c = 12.016(2) angstrom, alpha = 75.78(3)degrees, beta = 89.95(3)degrees, gamma = 83.45(3)degrees, V = 691.5(2) angstrom(3), Z = 2 and density (calculated) = 1.544 Mg/m(3); and (II) in the monoclinic space group P2(1)/c, unit cell a = 12.000(2), b = 7.518(2), c = 13.450(3) angstrom, beta = 97.87(3)degrees, V = 1202.0(5) angstrom(3), Z = 4, Density (calculated) = 1.600 Mg/m(3). Structure (I) includes a solvated CH3OH in the lattice. Final R indices [I > 2sigma(I)] are R1 = 0.0427, wR2 = 0.1075 for (I) and R1 = 0.0487, wR2 = 0.1222 for (II). R indices (all data) are R1 = 0.0470, wR2 = 0.1118 for (I) and R1 = 0.0623, wR2 = 0.1299 for (II). 5-Phenyl-2,4 diaminopyrimidine and 6-phenyl-1,2,4 triazine derivatives, which include lamotrigine (3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine), have been investigated for some time for their effects on the central nervous system. Both lamotrigine and 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine (code name BW1003C87), the subject of the present study, are anticonvulsant as well as neuroprotective in models of brain ischaemia and in a model of white matter ischaemia. BW1003C87 is a sodium channel blocker which also reduces the release of the neurotransmitter glutamate. The three dimensional structures reported here form part of a newly developed data base for the detailed investigation of members of this drug family and their biological activities.

X-ray crystallographic structures of two lamotrigine analogues: (I) 3,5-diamino-6-(2-chlorophenyl)-1,2,4-triazine water solvate and (II) 3,5-diamino-6-(3,6-dichlorophenyl)-1,2,4-triazine methanol solvate

The X-ray crystal structures of two lamotrigine derivatives (I) 3,5-diamino-6-(2-chlorophenyl)-1,2,4-triazine, C9H8ClN5, (465BL) as a hydrate, and (II) 3,5-diamino-6-(3,6-dichlorophenyl)-1,2,4-triazine, C9H7Cl2N5, (469BR) as a methanol solvate, have been carried out at liquid nitrogen temperature and room temperature, respectively. A detailed comparison of the two structures is given. Both are centrosymmetric with (I) in the orthorhombic space group Pbca, a = 12.2507(3), b = 15.7160(6), c = 21.71496(9) angstrom, Z = 16, and (II) in the monoclinic space group C2/c, a = 38.553(3), b = 4.9586(2), c = 14.546(2) angstrom, beta = 111.59(1)degrees, Z = 8. Final R indices [I > 2sigma(I)] for (I) are R1 = 0.0670, wR2 = 0.1515 and for (II) R1 = 0.0434, wR2 = 0.1185. Structure (I) has water of crystallization in the lattice and (II) includes a solvated CH3OH. Structure (I) is characterized by having two crystallographically independent molecules, A and B, of 465BL, per asymmetric unit. Molecule B has a very unusual feature in that the 2-chlorophenyl ring is statistically disordered, occupying site (1) in 87.5% of the structure and site (2) in 12.5% of the structure. Sites (1) and (2) are related by an exact 180 degrees pivot of the phenyl ring about the ring linkage bond. The presence of two independent molecules per asymmetric unit provides an ideal opportunity for the conformational flexibility of the molecule 465BL to be studied. Structure (I) also includes a further unusual feature in that the lattice contains one fully occupied water molecule and an additional solvated water which is only 33% occupied.

Low temperature X-ray crystallographic structures of two lamotrigine analogues: (I) 2-methyl,3-amino, 5-imino-6-(2,3-dichlorophenyl)-1,2,4-triazine water solvate and (II) 2-methyl,3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine isethionate, hemi-hydrate

The X-ray crystal structures of two lamotrigine derivatives (I) 2-methyl, 3-amino, 5-imino-6-(2, 3-dichlorophenyl)-1,2,4-triazine, C10H9Cl2N5, as the hemi hydrate and (II) 2-methyl,3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine, C10H10Cl2N5, as the isethionate-water solvate, have been carried out at liquid nitrogen temperature. A detailed comparison of the two structures is given. Both are monoclinic and centrosymmetric, with (I) in space group C2/c, and (II) in space group P2(1)/n. For (I) the unit cell dimensions are a = 19.5466(10), b = 7.5483(4), c = 15.7861(8) angstrom, beta = 91.458(3)degrees, volume = 2328.4(2) angstrom(3), Z = 8, density = 1.590 Mg/m(3); for (II). For (II) the unit cell dimensions are a = 6.0566(2), b = 11.0084(4) c = 23.9973(9) angstrom, beta = 92.587(3)degrees, volume = 1598.35(10) angstrom(3), Z = 4, density = 1.597 Mg/m(3). For (I) final R indices [I > 2sigma(I)] are R1 = 0.0356, wR2 = 0.0782 and R indices (all data) are R1 = 0.0424, wR2 = 0.0817. For (II) final R indices [I > 2sigma(I)] are R1 = 0.0380, wR2 = 0.0871 and R indices (all data) R1 = 0.0558, wR2 = 0.0949. Both structures have a molecule of water of crystallization and (II) also includes a solvated CH3SO3. Comparisons are made between the two structures. Structure (I) is very unusual in having a = NH group at position C5' on the triazine ring. No other examples of this particular substitution, which is usually -NH2, have been reported.

The structure of [Co(H-tptz)Cl-3] center dot H2O (tptz=2,4,6-tri(2-pyridyl)-1,3,5-triazine) prepared by crystallization from the ionic liquid, N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide

The structure of tris-chloro[2,6-bis(2'-pyridyl)-4-(2'-pyridinium)-1,3,5-triazine]cobalt(II) monohydrate, [Co(C18H13N6)Cl-3]center dot H2O (C2/c (No. 15), a = 7.783(11), b = 22.42(3), c = 11.001(15) angstrom, beta = 90.05(2)degrees), crystallized from the open air reaction of CoCl2 and 2,4,6-tri(2-pyridyl)-1,3,5-triazine in the ionic liquid, N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide is reported. The structure consists of six coordinate cobalt in an octahedral geometry bonded to the tridentate tptz ligand and three chlorines. The non-coordinating pyridyl group in the tptz ligand is protonated (with the protonated nitrogen crystallographically disordered over two possible sites), providing overall charge neutrality for the complex.

1-butyl-3-methylimidazolium 3,5-dinitro-1,2,4-triazolate: a novel ionic liquid containing a rigid, planar energetic anion

The novel ionic liquid, 1-butyl-3-methylimidazolium 3,5-dinitro-1,2,4-triazolate has been synthesized and exhibits an unexpectedly low melting point (35 degreesC) considering the size and shape of the rigid, planar anion; analogous tetraalkylammonium salts (methyl, ethyl and n-butyl) have also been prepared and the tetraethylammonium example was characterized by single crystal X-ray diffraction.

3,5-dimethyl-4-amino-1,2,4-triazole (Dat) as a tridentate ligand in the polymeric cations of [Ag-3(Dat)(2)](NO3)(3)

Colourless single crystals of [Ag-3(Dat)(2)](NO3)(3) were obtained from a reaction of silver(l) nitrate and 3,5-dimethyl-4-amino-1,2,4-triazole (Dat). In the crystal structure (orthorhombic, Fdd2, Z = 8, a = 1100.1(2), b = 3500.3(2), c = 1015.4(3) pm, R, = 0.0434) there are two crystallographically non-equivalent silver sites in a one (Ag1) to two ratio (Ag2). Both resemble linear N-Ag-N coordination although angles are 163 degrees and 144 degrees, respectively Each Dat ligand coordinates with the two ring nitrogen atoms at 216 to 219 pm and with one amino-nitrogen atom at 229 pro. According to the composition [Ag-3(Dat)(2)](3+) = [(Dat)Ag-3/2](3+), a polymeric structure is built with all Ag+ ions bridging.

Bis(trifluoromethyl)mercury(II) complexes with purine and 3,5-dimethyl-4 '-amino-triazole as ligands, [Hg(CF3)(2)(Pur)](4) and [Hg(CF3)(2)(Dat)](2)

Colourless single crystals of [Hg(CF3)(2)(Pur)](4) and [Hg(CF3)(2)(Dat)](2) were obtained from aqueous and etheric solutions of the respective components Purine, (imidazo[4,5-d]pyrimidine, Pur), 3,5-dimethyl-4 '-amino-triazole (Dat) and bis(trifluoromethyl)mercury(II), Hg(CF3)(2). [Hg(CF3)(2)(Pur)](4) crystallizes with the tetragonal system (P-4, Z = 8, a = 1486.8(2), c = 1026.2(l) pm, R-all = 0.0657) with tetrameric molecules consisting of four purine molecules bridged by slightly bent Hg(CF3)2 molecules forming a cage with the CF3 ligands surrounding this cage. The two modifications of [Hg(Dat)(CF3)2]2 (1: 170 K, triclinic, P-1, Z = 2, a 814.9(2), b = 845.4(2), c = 968.4(3) pm, alpha = 106.55(2)degrees, beta= 103.41(2)degrees, gamma = 110.79(2)degrees, R-all = 0.1189; II: monoclinic, P2(1)/c, Z = 8, a = 879.8(2), b = 1731.0(3), c = 1593.9(3) pm, beta = 106.89(2)degrees, R-all = 0.1199) both contain dimeric molecules that are stacked parallel to one crystal axis to strands which are arranged in a parallel fashion in I and rotated against each other in 11 by 110 degrees. In both, the tetrameric [Hg(CF3)(2)(Pur)](4) and the dimeric [Hg(CF3)(2)(Dat)](2) the Hg(CF3)(2) molecules are slightly bent (around 167 and 170 degrees) and rather weakly attached to the N-donor ligands Pur and Dat with Hg-N distances around 272 pm, although in both cases the Hg atoms bridge between two ligand molecules.

Synthesis and Phosphorus Sulfur Bond-Cleavage Of 3'- Thiothymidylyl(3'5')Thymidine

The title compound is readily prepared from 5'-O-monomethoxytrityl-3'-thiothymidine (5); cleavage of the P–S bond can be accomplished by mild oxidative hydrolysis.

ABSOLUTE DOUBLY DIFFERENTIAL CROSS-SECTIONS FOR ELECTRON-EMISSION IN COLLISIONS OF 3.5-MEV/U FE(17+) AND FE(22+) IONS WITH HE AND AR GAS TARGETS

Absolute doubly differential cross sections have been measured as a function of electron energy and angle of observation for electron emission in collisions of 3.5-MeV/u Fe17+ and Fe22+ ions with He and Ar gas targets under single-collision conditions. The measured electron emission cross sections are compared to theoretical and scaled cross sections based on the Born approximation. The results using intermediate-mass ions are discussed with reference to previously reported cross sections from collisions with highly charged lighter- and heavier-ion species at MeV/u projectile energies. The continuum-distorted-wave-eikonal-initial-state approximation shows good agreement with experiments except in the

M-L band x-rays (3-3.5 KeV) from palladium coated targets for isochoric radiative heating of thin foil samples

We describe experiments designed to produce a bright M-L band x-ray source in the 3-3.5 keV region. Palladium targets irradiated with a 10(15) W cm(-2) laser pulse have previously been shown to convert up to similar to 2% of the laser energy into M-L band x-rays with similar pulse duration to that of the incident laser. This x-ray emission is further characterized here, including pulse duration and source size measurements, and a higher conversion efficiency than previously achieved is demonstrated (similar to 4%) using more energetic and longer duration laser pulses (200 ps). The emission near the aluminium K-edge (1.465-1.550 keV) is also reported for similar conditions, along with the successful suppression of such lower band x-rays using a CH coating on the rear side of the target. The possibility of using the source to radiatively heat a thin aluminium foil sample to uniform warm dense matter conditions is discussed.