摘要:

AbstractThe electronic behavior of sandwich‐type rare earth octaethylporphyrinates Ln(oep)2and Ln2(oep)3(Ln=Ce, Pr and Eu) was characterized by measurements of the UV‐vis or near infrared spectra and D.C. conductivity. However, the conductivity values measured at room temperature were distributed in an order of 10−7to 10−8S·cm−1even after the partial oxidation of complex with the complexes with iodine and no remarkable change was observed among the complexes such as LnIV(Por2‐)2(Ln=Ce) and LnIV(Por2‐)(Por.−) (Ln=Ce) or Ln2III(Por2‐)3and Ln2

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120301

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractBased on a simple nonideal chemical reaction model, the closed system with reversible nonideal reactions and illumination is shown to be able to exhibit sustained oscillation. The essential points in the occurrence of such oscillations are the nonideality of reacting media, which gives rise to multiple chemical equilibria, and the energy flow through illumination and heat conduction, which gives rise to spontaneous transitions repeatedly between the multiple equilibrium states. During the oscillation, reacting media undergo only reversible chemical transformation and all irreversibilities are restricted to the coupling of the system to external world. This oscillation provides an example of the so‐called endoreversible machine and a possible way to convert radiation energy of the light directly into mechanical energ

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120302

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe molecular structures of thermally structurized polyacrylonitrile (PAN), that is, polypyridinopyridine (PPyPy) series have been investigated by using quantum chemistry semiempirical MNDO, CNDO/2‐CO methods. The changing regularities of structural stability and electronic properties are pointed out. The analyses of the energy band structures indicate that the energy gaps will become smaller, intrinsical conductivities will increase when the quasi‐one‐dimentional (1D) series of PPyPy molecule widen toward two‐dimention (2D), which is consistent with the experimental results of polymerization degree (PD) and electrical conductivity increase with the increasing of pyrolyzed temp

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120303

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractWe report the accurate determinations of quantum mechanical state‐to‐state probabilities for reactions Cl + H2→ HC1 + H and H' + HC1 → H'Cl + H by the generalized Newton variational principle, on the most accurate available potential energy surface. We compare the results for three versions of realistic potential energy surfaces, and to those from hyperspherical close‐coupling cal

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120304

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe three‐dimensional structure of trichosanthin at 2.7Å resolution has been improved further, by refitting one of theC‐terminal tails,adjusting 16residues in the molecular surface regions, discarding some water molecules with highBvalues, and adjusting weights during the further refinement. TheR‐factor has been reduced to 18.5% and the r.m.s deviations from ideal geometry are also improved. The structures of the two molecules in the monoclinic asymmetric unit and the only molecule in the orthorhombic asymmetric unit are compared with one another. The main‐chain structures for most of the residues in the three molecules are substantially the same. However, the courses of the threeC‐terminal tails are completely different, and the intermolecular interactions resulting from the particular packing of the molecules in the crystals account for the differences. The strand βe‐2 and the preceding β‐turn in small domain show large r.m.s. deviations among the three molecules and they are also involved in intermolecu

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120305

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractFour binuclear Co(II), Ni(II) and Cu(II) complexes bridged by oxamidate (oxd) group have been synthesized, namely Co2(byp)2(oxd)(C104)2(1), Co2(Me2bpy)2(oxd)(ClO4)2·H2O (2), Ni2(bpy)2(oxd)(ClO4)2·2H2O (3) and Cu2(Me2bpy)2(oxd)(NO3)2(4). (bpy=2,2′‐bipyridyl, Me2‐bpy=4,4′‐dimethylbipyridyl, oxd=oxamidate) The complexes are characterized by IR, UV spectra, EPR and variable‐temperature magnetic susceptibility (4–300 K). The susceptibility data for complexes 1 and 3 were least‐squares fit to the susceptibility equation derived from the spin Hamiltonian Ȟ=‐2J · Š1·2. The exchange integral,J, was found to be equal to −3.62 cm−1in 1 and −1.82 cm−1in 3. This indicates a weak antiferromagnetic spin exchange int

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120306

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe synthesis spectroscopic properties and tautomerism of four novel mono‐mesosubstituted(R)‐octamethylporphyrins (R=o‐hydroxybenzyl,p‐aminobenzyl, 4‐pyridinyl, and ferrocenyl) were investigated. It was found that the porphyrins2, 3 could be directly prepared in good yields via the coupling reaction of salicylaldehyde andp‐aminobenzyl aldehyde with octamethyl‐1′,8′‐dideoxy‐ac‐biladiene dihydrobromide, respectively. The free energy of activation (ΔG≠) of the tautomerism of the porphyrins was calculated and interpreted in terms of electronic and steric nature. In contrast with 2‐substituted‐5,10,15,20‐tetraphenylporphyrins, the substituents in meso position do not change the relat

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120307

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe solid‐solid state reactions ofo‐aminobenzoic acid with Zn(OAc)2·2H2O, Cu(OAc)2·H2O, Ni(OAc)2·4H2O and Mn(OAc)2·4H2O result in the formation of corresponding complexes M(OAB)2(M = Zn(II), Cu(II), Ni(II), Mn(II)). XRD, IR and elemental analysis methods have been used to characterize the solid products. The activation energies of these reactions, which are calculated from the kinetic data obtained by means of the isothermal electrical conductivity measurement method, have been found to increase in the order: Cu(OAc)2·H2O(37.7 kJ‐mol−1)∼Mn(OAc)2·4H2O (39.7 kJ·mol−1)

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120308

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractThe reaction of CuCl2·2H2O or NiCl2·6H2O with K2(C5H6S4) [potassium salt of 6,7‐dihydro‐5H‐1,4‐dithiepin‐2,3‐dithiolate] under nitrogen atmosphere resulted in the isolation of [Cu(C5H6S4)2]−or [Ni(C5H6S4)2]−as the tetrabutylammonium salt. Both complexes show characteristic IR and UV −Vis absorptions of transition metal dithiolenes. Cyclic voltammograms contain two waves indicating a two step electrochemical procedure [M(C5H6S4)2]0= [M(C5H6S4)2]1‐= [M(C5H6S4)2]2‐Single crystal structure study has been carried out on the nickel complex. Crystal of [Bu4N][Ni(C5H6S4)2] belongs to monoclinic space group P21/c witha=17.576(5),b=10.883(2),c=17.773(4) A, β=91.07(2)°, Z=4, and ρ(calcd.)=1.348 g/cm3. Final result isR=0.059 for 2959 reflections. The NiS4core exhibits square planar coordination with average Ni—S bond length of 2.134(5) Å. There are not anion pairs in crystal. The anions stack along a and c axes while the cations intercalate in them. The nearest S—S contact is 4.429 Å. The solid powder ESR spectrum of the nickel complex shows three broadening signals atg1=2.097,g2=2.042,g3=2.022. Magnetic susceptibility data for [Bu4N][Ni(C5H6S4)2] reveal enhance

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120309

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY

摘要:

AbstractNaY zeolite entrapped Ru3(CO)12cluster has been synthesized from RuCl3ion‐exchanged NaY, which is well characterized by IR and Raman spectroscopies and CO chemisorption. When the Ru3+/NaY sample is heated from 298 K to 393 K for 25 h and for 10 h at 393 K, the sample colour changes from dark to brown‐yellow. Thein situinfrared spectrum exhibits absorption bands at 2130, 2064, 2040, 2017, 1990, 1953 and 1925 cm−1. The bands at 2130 cm−1arises from the Rumn+(CO)lm=1–3;n= 1–3;l= 1–12). The bands at 2064, 2040, 2017 and 1990 cm−1are proposed to be associated with the Ru3(CO)12/NaY, which are close to Ru3(CO)12crystalline. Furthermore, the Raman results provide bands at 150 and 185 cm−1, which can be attributed to Ru—Ru bonds of the sample as in the case of Ru3(CO)12crystalline, for which the A'1Ru—Ru stretching mode is assigned to 185 cm−1and E'1Ru—Ru stretching mode is assigned to a band at 150 cm−1, respectively. CO chemisorption of [Ru3]/NaY gives a CO/Ru ratio of 3.85, which is similar to the

ISSN:1001-604X    

DOI:10.1002/cjoc.19940120310

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1994

数据来源: WILEY