1,721,726 research outputs found
Methanolysis of nitrile functionalized pendant arm derivatives of 1,4,7-triazacyclononane upon coordination to CuII
No full textREDETERMINATION OF THE STRUCTURE OF POTASSIUM TETRANITROPALLADATE(II)
No full textK2Pd(NO2)4, M(r) = 368.58, monoclinic, P2(1)/c, a = 9.254 (5), b = 12.747 (3), c = 7.805 (2) angstrom, beta = 96.43 (2)-degrees V = 914.9 angstrom3 [from setting angles for 14 0kl and 12 h0l data, 20 = 18-340, lambda(Mo Kalpha) = 0.71073 angstrom], Z = 4, D(x) = 2.676 Mg m-3, mu = 2.95 mm-1, F(000) = 704, T = 295 K, R = 0.031 for 2327 unique observed reflections. There are two crystallographically independent Pd(NO2)42- ions, each square planar with symmetry 1BAR (C(i)); Pd-N distances are in the range 2.018 (2)-2.047 (2) angstrom
NA2[RU(NO2)4(NO)(OH)].2H2O - A REDETERMINATION
No full textDisodium hydroxotetranitro(nitroso)ruthenate(III) dihydrate, M(r) = 414.1, monoclinic, C2/m, a = 12.8765 (6), b = 14.5867 (9), c = 7.4478 (4) angstrom, beta = 121.521 (3)-degrees, V = 1192.5 angstrom 3, Z = 4, D(x) = 2.306 Mg m-3, lambda-BAR(Mo K-alpha) = 0.71073 angstrom, mu = 1.430 mm-1, F(000) = 808, T = 298 K, R = 0.0251 for 1760 unique observed reflections. We have redetermined the structure of the title compound by single-crystal X-ray diffraction. After recalculation of the bond lengths derived in the neutron diffraction study, the distances involving the non-H atoms show no significant differences between the two determinations
(1,3-Dimethylimidazolidine-2-selone-kappa Se)bis(1,10-phenanthroline-kappa N-2,N ')-copper(II) bis(perchlorate) and bis(2,2 '-bipyridyl-kappa N-2,N ')(imidazolidine-2-thione-kappa S)copper(II) bis(perchlorate)
No full textIn the rst title salt, [ Cu( C12H8N2) (2)( C5H10N2Se)]( ClO4) (2), the Cu-II centre occupies a distorted trigonal - bipyramidal environment de ned by four N donors from two 1,10- phenanthroline ( phen) ligands and by the Se donor of a 1,3- dimethylimidazolidine-2-selone ligand, with the equatorial plane defined by the Se and by two N donors from different phen ligands and the axial sites occupied by the two remaining N donors, one from each phen ligand. The Cu - N distances span the range 1.980 ( 10) - 2.114 ( 11) angstrom and the Cu - Se distance is 2.491 ( 3) angstrom. Intermolecular pi-pi contacts between imidazolidine rings and the central rings of phen ligands generate chains of cations. In the second salt, [ Cu( C10H8N2)(2-)( C3H6N2S)]( ClO4) (2), the Cu-II centre occupies a similar distorted trigonal-bipyramidal environment comprising four N donors from two 2,20- bipyridyl ( bipy) ligands and an S donor from an imidazolidine- 2- thione ligand. The equatorial plane is de ned by the S donor and two N donors from different bipy ligands. The Cu - N distances span the range 1.984 ( 6)-2.069 ( 7) angstrom and the Cu - S distance is 2.366 ( 3) angstrom. Intermolecular pi-pi contacts between imidazolidine and pyridyl rings form chains of cations. A major difference between the two structures is due to the presence in the second complex of two N - H center dot center dot center dot O hydrogen bonds linking the imidazolidine N H hydrogen- bond donors to perchlorate O- atom acceptors
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A new class of mixed az-thioether crown containing the 1,10-phenanthroline sub-unit
No full textThe new aza-thioether crowns [15]ane(phen N-2)S-3 and [19]ane(phen N-2)S-4 have been synthesised. Their complexation with nickel(II) salts afforded a range of octahedral complexes. The single crystal structures of [Ni{[15]ane(phen N-5)S-3)}(NCMe)][BF4](2), [NiCl{[15]ane(phen N-2)S-3}]BF4 . dmf(dmf = dimethylformamide) and [Nil{[15]ane(phen N-2)S-3}][I-3] have been determined and confirm N2S3 donation of the aza-thioether crown in a folded conformation to Ni-II with the sixth co-ordination site taken up by MeCN, Cl- and I- respectively. The complex [Ni2Cl2{[19]ane(phen N-2)S-4}(2)][BF4](2) . 3MeNO(2) shows a dichloro-bridged binuclear structure with the aza-thioether crown bound via only two S- and two N-donors, with two thioether S-donors unbound. A dichloro-bridged binuclear structure was found also for [Ni2Cl2{[12]ane-(py N)S-3}(2)][BF4](2) . 1.5MeNO(2). The redox properties of [Ni{[15]ane(phen N-2)S-3}(NCMe)][BF4](2) in MeCN have been examined
SYNTHESIS, MOLECULAR AND CRYSTAL-STRUCTURES OF ARENE DERIVATIVES OF [RU6C(CO)17]
No full textThe complexes [Ru6C(CO)14(eta6-C6H4Me2-1,3)] 1, [Ru6C(CO)14(eta6CH3Et3-1,3,5)] 2 and [Ru6C-(CO)14(mu3-eta2:eta2:eta2-C16H16)] 3 have been prepared from the reaction of [Ru3(CO)12] and the appropriate arene. The molecular and crystal structures of the three derivatives have been established by single-crystal X-ray diffraction studies. Complexes 1 and 2 carry the arene fragment bound in a terminal fashion. Crystalline 1 contains two independent molecules showing different rotameric conformations of the xylene ligands. The [2.2]paracyclophane complex 3 provides the first example of a mono(arene) derivative of [Ru6C(CO)17] to contain the mu3-eta2:eta2:eta2-bonding mode. The molecular organization in the crystal structures of 1, 2 and 3 was also determined
SEQUENTIAL SYNTHESIS OF SOME TETRAOSMIUM ARENE CLUSTERS
No full textOn activation with Me3NO the tetrahydrido-tetranuclear cluster [Os4(mu-H)4(CO)12] 1 underwent reaction with cyclohexa-1,3-diene in CH2Cl2 under ambient conditions to give, as the major products, the four organometallic clusters [Os4(mu-H)3(CO)11(eta3-C6H9)] 2, [Os4(mu-H)2(CO)12(eta2-C6H8)] 3, [Os4(mu-H)2(CO)11(eta4-C6H8)] 4 and [Os4(mu-H)2(CO)10(eta6-C6H6)] 5. On heating in hexane, 3 is converted into 4 and subsequently 4 into 5. Compound 5 underwent further reaction with Me3NO in CH2Cl2 in the presence of cyclohexa-1,3-diene to produce [Os4(CO)9(eta6-C6H6)(eta4-C6H8)] 6 and [Os4(mu-H)2(CO)8(eta6-C6H6)(eta4-C6H8)] 7. Structural analyses of 4 and 7 by single-crystal X-ray diffraction have shown that the C6H8 ligand is bonded through two alkene bonds and that the benzene ligand in 7 is co-ordinated in an eta6 fashion. In each case the ligands are bonded to single osmium atoms only. Compound 5 was also found to react with Me3NO in CH2Cl2 in the presence of benzene yielding [Os4(CO)8(eta6-C6H6)2] 8, whilst with either toluene or mesitylene it undergoes arene displacement to produce [Os4(mu-H)2(CO)10(eta6-C6H5Me)] 9 or [Os4(mu-H)2(CO)10(eta6-C6H4Me2-1,3)] 10 respectively
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