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  • 1
    Electronic Resource
    Electronic Resource
    On the relationship of effective Reynolds number and Strouhal number for the laminar vortex shedding of a heated circular cylinder (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 12 (2000), S. 1401-1410 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The laminar vortex shedding of airflow behind a circular cylinder with different heating temperatures was experimentally investigated with emphasis on the relationship of wake frequency and the Reynolds number. A new method to generate the two-dimensional parallel vortex shedding for the heated cylinder was developed and tested. An "effective Reynolds number" that employs a kinematic viscosity computed from an "effective temperature" is used to account for the temperature effects on the vortex shedding frequency. The present result shows that the frequency data could be successfully collapsed with the effective temperature computed by Teff=T∞+0.28(TW−T∞) for a wide range of cylinder temperatures, T∞ and TW being the free-stream temperature and cylinder surface temperature, respectively. Moreover, the relationship between Strouhal number and effective Reynolds number was found to be "universal." The physical interpretation of Teff and the applicable region of the St–Reeff curve are discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870391
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrogen-donor base adducts of bis(O,O′-di-isoamyldithiophosphato)nickel(II) (2000)
    Springer
    Transition metal chemistry 25 (2000), S. 715-719 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of NiII complexes with the O,O′-di-isoamylester of dithiophosphoric acid and nitrogen-donor ligands of composition [Ni(i-Am2dtp)2(L)]; [dtp = O2PS2 −; L = 2,2′-bipyridine (bpy); 1,10-phenanthroline (phen); 5-nitro-1,10-phenanthroline (nphen); 4,7-diphenyl-1,10-phenanthroline (baphen); 2,9-dimethyl-1,10-phenanthroline (neo), 2-aminomethylpyridine (amp), 2-(2-aminoethyl)pyridine (aep), 2,2′-dipiridylamine (dpa), 1,2-diaminopropane (1,2-dap) or trans 1,2-diaminocyclohexane (dch)] have been prepared. The compounds have been characterized by elemental analyses (C,H,N,S), electronic and i.r. spectroscopy, magnetic and conductivity measurements and by cyclic voltammetry. The results show that all complexes behave as non-electrolytes in acetone. Electronic spectra and magnetic moments suggest a distorted cis-octahedral geometry around the NiII atom [μeff/μB ∈ 〈3.10, 3.40 〉], except for [Ni(i-Am2dtp)2(aep)], where the measured temperature dependence of the magnetic susceptibility proved the tetrahedrally coordinated nickel [4.06 μeff/μB (298 K) – 3.20 μeff/μB (80 K)]. In the [Ni(i-Am2dtp)2(neo)] complex, the nickel atom is penta-coordinated. The X-ray crystal and molecular structure of [Ni(i-Am2dtp)2(1,2-dap)] has been determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007016617249
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis, characterization and biological activity of two nickel(II) complexes with 6-(2-chlorobenzylamino)purine (2000)
    Springer
    Transition metal chemistry 25 (2000), S. 265-269 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Compounds of composition [Ni(L)(H2O)2Cl] and [Ni(L)(H2O)(NO3)] · EtOH [HL = 6-(2-chlorobenzylamino)purine] have been synthesized and characterized by elemental analyses, i.r. and electronic spectra, magnetic measurements and mass spectroscopy as tetrahedral nickel(II) complexes. The geometry of both complexes has been optimized using molecular mechanics modelling. Although the monoanionic ligand L is potentially bidentate, we assume that the coordination to nickel is via the N9 atom only. Cytokinin and anti-cancer activities of the complexes were also tested in an Amaranthus cytokinin bioassay and in an in vitro MTT-based cytotoxicity assay, respectively. In human T-lymphoblastic leukemia cell line CCRF-CEM both complexes showed potent cytotoxic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007069011141
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  • 4
    Electronic Resource
    Electronic Resource
    Syntheses of 1-Arylidenamino-2,4-disubstituted-2-imidazoline-5-ones. X-Ray Structure of 1-Benzylidenamino-2-phenyl-4-benzylidene-2-imidazoline-5-one (1999)
    Springer
    Monatshefte für Chemie 130 (1999), S. 471-479 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. 1-Arylidenamino-2 ; 4-disubstituted-2-imidazoline-5-ones; Syntheses; X-Ray structure; Semi-empirical quantum-chemical PM3 calculations.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Diese Arbeit beschäftigt sich mit Synthese und Untersuchung von 1-Aryliden-amino-2,4-disubstituierten-2-imidazolin-5-onen. Die Verbindungen wurden durch Cyclisierung von Arylidenhydraziden von 2-Benzoylamino-3-arylacrylsäure hergestellt, welche durch Kondensation von 2-Benzoylamino-3-arylacrylsäure mit substituierten Benzaldehyden gewonnen wurden. Die Struktur von 1-Benzylidenamino-2-phenyl-4-benzyliden-2-imidazolin-5-onwurdemittels Einkristallröntgenstrukturanalyse bestimmt. Eine Geometrieoptimierung der Titelverbindung auf der semiempirischen PM3-Ebene wird ebenfalls vorgestellt und mit den Röntgendaten verglichen.
    Notes: Summary.  The present paper deals with syntheses and study of 1-arylidenamino-2,4-disubstituted- 2-imidazoline-5-ones. The compounds were prepared by cyclization of arylidenehydrazides of 2-benzoylamino-3-arylacrylic acid which were synthesized via condensation of hydrazides of 2-benzoylamino-3-arylacrylic acid with substituted benzaldehydes. The structure of 1-benzylidenamino-2-phenyl-4-benzylidene-2-imidazoline-5-one was determine by single crystal X-ray analysis. Geometry optimization of the above compound at the semi-empirical PM3 level is also presented and compared with the X-ray data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010226
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  • 5
    Electronic Resource
    Electronic Resource
    Investigation of {1,2-bis(diphenylphosphino)ethane-P,P′}-(dithiocarbonato-S,S′)-nickel(II) (1996)
    Springer
    Transition metal chemistry 21 (1996), S. 81-84 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reaction of bis(iso-propylxanthato)nickel(II) with 1,2-bis(diphenylphosphino)ethane (dppe) in a 1∶1 molar ratio affords [Ni(S2CO)(dppe)], which, on the basis of its magneto-chemical and spectral properties, has been characterized as a square-planar Ni complex. The complex was one-electron irreversibly oxidized at a potential of 0.673 V versus s.c.e. The crystal and molecular structure of a twinned crystal of the complex has been elucidated, and consists of two crystallographically independent molecules in which each Ni atom is coordinated by two S atoms from the dithiocarbonate ligand and two P atoms from the dppe ligand in an approximately square-planar arrangement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166020
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  • 6
    Electronic Resource
    Electronic Resource
    Novel xanthate complexes of nickel. X-ray structure of [NiBr(S2CO-i-Am)(PPh3)] at 150 K (1999)
    Springer
    Transition metal chemistry 24 (1999), S. 156-159 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nickel(II) isopropylxanthate complexes of composition [Ni2(μ-L)2(S2CO-i-Pr)2]·xCHCl3 (1) and (2) {HL = thiophenol or 4-methylthiophenol, x = 1/2 or 1/3} and [Ni(bpy)(S2CO-i-Pr)]Br (3) {bpy = 2,2′-bipyridine} have been synthesized and characterized by elemental analyses, electronic and i.r. spectroscopy, magnetic moment studies and conductivity measurements. The results show that (1) and (2) are non-electrolytes, square-planar, binuclear nickel(II) complexes bridged via two L1− ligands, while compound (3) is ionic (1:1); the donor atom arrangement around the nickel(II) centre is tetrahedral with an NiS2N2 chromophore. The geometry of the [Ni(bpy)(S2CO-i-Pr)]+ cation has been optimized using MM+ calculations. The crystal and molecular structure of [NiBr(S2CO-i-Am)(PPh3)], as an example of an i-Am derivative of a starting complex for preparation of all the above compounds, has been determined. X-ray analysis of the complex reveals distorted square-planar geometry at the metal centre with an S2PBr donor set.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006916727435
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  • 7
    Electronic Resource
    Electronic Resource
    Heterocyclic nickel(II) dithiocarbamates with aromatic thiols as bridging ligands (1999)
    Springer
    Transition metal chemistry 24 (1999), S. 304-305 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Binuclear NiII dithiocarbamates, with aromatic monothiols as bridging ligands, of composition [Ni(μ-L) (Rdtc)]2 [dtc = S2CN, R = C4H8O (morph), C5H10 (pip), C4H8 (pld); HL = thiophenol, 4-methylthiophenol or 2-thionaphthol] and [Ni(μ-L)(HR1dtc)]2 {R1 = C11H11N2O (aap)} have been prepared and characterized by elemental analyses, i.r. and electron spectroscopy, magnetochemical and conductivity measurements, and thermal analysis. The methods used indicate that the complexes are diamagnetic, complex non-electrolytes with two square-planar NiS4 chromophores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006948208861
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  • 8
    Electronic Resource
    Electronic Resource
    Nickel(II) complexes with dicyanamide and tetramines (1999)
    Springer
    Transition metal chemistry 24 (1999), S. 459-462 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Four new pseudohalide complexes of the type [NiL{N(CN)2}2] (L = N(CH2CH2NH2)3, TAA; triethylenetetramine, TTA) and [NiL{N(CN)2}]ClO4 have been prepared and characterized by spectroscopic and magnetic methods. The X-ray crystal structures of [Ni(TAA){N(CN)2}2] and [Ni(TTA){N(CN)2}2] have been determined, and analyses show that in both complexes the Ni ion posseses distorted octahedral geometry. The temperature dependence of the magnetic susceptibility of [Ni(TTA){N(CN)2}](ClO4) was measured, but no antiferromagnetic interaction was detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006910319984
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  • 9
    Electronic Resource
    Electronic Resource
    Xanthate complexes of nickel with nitrogen donor ligands. Part V (1999)
    Springer
    Transition metal chemistry 24 (1999), S. 633-637 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nickel(II) xanthate complexes of general formula, [Ni(Rxa)2(L)] [R = i-Pr, i-Am, xa = OCS− 2, L = 4,7-diphenyl-1,10-phenanthroline(baphen), 4,4′-dimethyl-2,2′-bipyridyl (me2bpy), 2-9-dimethyl-1,10-phenanthroline(neo) or trans-1,2-diaminocyclohexane (dch)] and [Ni(Rxa)(cyclam)](Rxa) (= 1,4,8,11-tetraazacyclotetradecane) have been synthesized and characterized by elemental analyses, i.r. and electronic spectroscopy, magnetic and conductivity measurements. The complexes with cyclam were studied by cyclic voltammetry. Values of magnetic moments at room temperature lie within the 3.25–3.51 B.M. range and thus indicate the presence of two unpaired electrons, except for the complexes with cyclam, where the anomalous values of 1.76 and 1.74 B.M. were obtained in respect to the nickel(II) complexes. Magnetic susceptibility data for [Ni(i-Prxa)(cyclam)](i-Prxa) were measured over the 79–298 K range and indicate no exchange interaction between paramagnetic nickel(II) centres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006923722773
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  • 10
    Electronic Resource
    Electronic Resource
    Nickel(II) xanthates with nitrogen heterocycles as bridging ligands (1999)
    Springer
    Transition metal chemistry 24 (1999), S. 38-41 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract New homopolynuclear nickel(II) xanthate complexes with nitrogen donor heterocycles as bridging ligands have been prepared, namely [Ni(Rxa)2(μ-L)]n and [Ni2(Rxa)4(μ-L1)], where R=i-Pr,i-Am; xa=OCS2− L=1,2-bis(4- pyridyl)ethane (bpe), 4,4′-dithiodipyridyl (dtp), 1,2-bis(4- pyridyl)ethylene (dpe), 4,4′-trimethylene-dipyridine (tmd); L1=2,3-bis(2-pyridyl)pyrazine (bpp), 2,4-bis(5,6- diphenyl-1,2,4-triazine-3-yl)pyridine (bdt), or 2,4,6-tris(2- pyridyl)-1,3,5-triazine (tpt). The compounds have been characterized by elemental analyses, i.r. and electronic spectroscopies, magnetochemical and conductivity measurements. The results show that the [Ni(Rxa)2(μ-L)]n complexes are linear polymers in which the nitrogen heterocycles bridge between the nickel(II) ions, which are coordinated by four sulfur and two nitrogen atoms and have trans-octahedral geometry. The nearly constant values of the effective magnetic moment (3.36–3.34 μeff/μB) over the 77–295 K temperature range indicate that exchange interactions are lacking among the paramagnetic centres in the linear structure, [Ni(i-Amxa)2(dpe)]n. The variable- temperature magnetic susceptibilities of the [Ni2(i-Prxa)4(bpp)] (3.00–2.95μeff/μB per Ni atom), [Ni2(i-Prxa)4(bdt)] (2.72–2.63 μeff/μB per Ni atom), and [Ni2(i-Amxa)4(tpt)] (2.76–1.87 μeff/μB per Ni atom) were measured down to liquid nitrogen temperature. In the case of binuclear nickel(II) complexes with bdt or tpt, antiferromagnetic coupling between the nickel(II) ions was detected, giving the exchange integral J=−4.0cm−1 and −29.6cm−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006987319004
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