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11.
Brian Hudson David J. Livingstone Elizabeth Rahr 《Journal of computer-aided molecular design》1989,3(1):55-65
Summary Pattern recognition methods, particularly the unsupervised learning techniques, are well suited for the preliminary analysis of the large data sets produced by computer chemistry. The use of linear and non-linear display methods for such exploratory analysis are exemplified with the aid of two data sets of biologically active molecules. Advantages and disadvantages of these techniques are discussed. 相似文献
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Murugan R Mallavarapu GR Padmashree KV Rao RR Livingstone C 《Natural product communications》2010,5(12):1961-1964
The volatile oil of the leaves of Pogostemon heyneanus Benth. (Lamiaceae) was analyzed by GC and GC-MS. Twenty-six components representing 96.0% of the oil were identified. The major components of the oil were acetophenone (51.0%), beta-pinene (5.3%), (E)-nerolidol (5.4%), and patchouli alcohol (14.0%). Comparison of the compositions of the oils of P. heyneanus and P. cablin (Blanco) Benth. (Patchouli oil) showed wide variation between them. Though 13 sesquiterpenes and oxygenated sesquiterpenes were detected in both oils, their concentrations in the oils differed widely. Acetophenone, benzoyl acetone and (E)-nerolidol present in the oil of P. heyneanus were not detected in patchouli oil. 相似文献
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Manoranjan Das Raymund M. Golding Stanley E. Livingstone 《Transition Metal Chemistry》1978,3(1):112-117
Summary The magnetic moments of the iron(III) chelates of the fluorinated monothio--diketones RC(SH)=CFICOCF3 (R = 2-thienyl, -naphthyl, Ph, p-McC6H4, p-FC6H4,p-ClC6H4, m-MeC6H4, m-CIC6H4 m-BrC6H4) have been measured over a temperature range. The moments vary from 5.49 to 2.16 B.M. at room temperature and are temperaturedependent, falling to as low as 1.82 B.M. at 83 K. The quadrupole splittings from the Messbauer spectra at room temperature are within the range 0.70 to 1.80 mm/s, whereas at 77 K they lie within the range 1.70 to 1.95 mm/s. These results indicate that the iron atom is in an intermediate effective crystal field, which depends to a small extent on the temperature and the substituent R and increases in the order: C4H3S < -C10 < p-XC6H4 < Ph < m-XC6H4 (X = Me, F, CI or Br). Also the results indicate the degree of bonding asymmetry of the iron atom. 相似文献
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Summary The Schiff bases RC(OFl)=CFlC(CF3)=NNlJC(S)NH2 (R = 2-thienyl, Ph,p-BrC6H4,p-MeC6H4,p-MeOC6H4,m-McOC6H4, -naphthy], Pri) have been prepared by condensation of fluorinated -diketones with thiosemicarbazide. By the loss of one or two protons from their tautomeric iminothiol form RC(OH)=CHC(CF3)=NN=C(SH)NH2 the Schiff bases act as (i) doubly negatively charged ONS tridentate or (ii) singly negatively charged NS bidentate ligands, respectively. The Schiff bases give dimeric µ2-dithiolo-bridged complexes M(ONS)2 (M = Ni, Pd, and Pt). The thiolo-bridges in the nickel complexes can be split by reaction with pyridine to give the monomeric compounds Ni(ONS)py, whereas the palladium and platinum complexes are unreactive towards pyridine. When R = 2-thienyl orp-BrC6H4, 1:2 complexes of the type M(HONS)2 (M = Pd or Pt) were isolated. With copper(II) the Schiff bases yield the complexes CuII(ONS). CuI(HONS) which are considered to have a polymeric structure involving -thiolo-bridges. 相似文献
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Structural and Mechanistic Insights into s‐Block Bimetallic Catalysis: Sodium Magnesiate‐Catalyzed Guanylation of Amines 下载免费PDF全文
Marco De Tullio Dr. Alberto Hernán‐Gómez Dr. Zoe Livingstone Prof. William Clegg Dr. Alan R. Kennedy Dr. Ross W. Harrington Prof. Antonio Antiñolo Antonio Martínez Dr. Fernando Carrillo‐Hermosilla Prof. Eva Hevia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(49):17646-17656
To advance the catalytic applications of s‐block mixed‐metal complexes, sodium magnesiate [NaMg(CH2SiMe3)3] ( 1 ) is reported as an efficient precatalyst for the guanylation of a variety of anilines and secondary amines with carbodiimides. First examples of hydrophosphination of carbodiimides by using a Mg catalyst are also described. The catalytic ability of the mixed‐metal system is much greater than that of its homometallic components [NaCH2SiMe3] and [Mg(CH2SiMe3)2]. Stoichiometric studies suggest that magnesiate amido and guanidinate complexes are intermediates in these catalytic routes. Reactivity and kinetic studies imply that these guanylation reactions occur via (tris)amide intermediates that react with carbodiiimides in insertion steps. The rate law for the guanylation of N,N′‐diisopropylcarbodiimide with 4‐tert‐butylaniline catalyzed by 1 is first order with respect to [amine], [carbodiimide], and [catalyst], and the reaction shows a large kinetic isotopic effect, which is consistent with an amine‐assisted rate‐determining carbodiimide insertion transition state. Studies to assess the effect of sodium in these transformations denote a secondary role with little involvement in the catalytic cycle. 相似文献