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Analogous Compounds (analogous + compound)
Selected AbstractsOn the sequence of three related phases of [Ni(H2O)2(15-crown-5)](HSO4)2 in the temperature range 110,295,KACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2010Maxime A. Siegler Attempts to prepare the compound [Ni(H2O)2(15-crown-5)](X)2 were eventually successful with X = NO provided that a synthetic route aimed at restricting water was followed. Application of this method was extended to make the analogous compound with X = HSO, for which three symmetry-related phases were isolated between 295 and 110,K: a room-temperature phase with Z, = ½ [phase (I)], an intermediate-temperature phase with Z, = 1 [phase (II)] and a low-temperature phase with Z, = 2 [phase (III)]. The phases are related by two reversible solid,solid phase transitions, and both transitions take place without a significant loss of crystallinity. In the phase sequence (I) , (II) , (III) (Z,: ½, 1 , 2), the crystal packing remains remarkably similar but the degree of order in the crystal changes significantly; the structure is very disordered at room and intermediate temperatures but is ordered at 110,K. The compound [Ni(H2O)2(15-crown-5)](HSO4)2 has a complicated hydrogen-bonding network, which contains O,H...O bonds between the counterions. Structural changes are largest along some face-diagonal directions in the sequence (I) , (II) , (III). [source] Solid-state compounds of stereoisomers: cis and trans isomers of 1,2-cyclohexanediol and 2,3-tetralindiolACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2007Michael A. Lloyd The phases of 1,2,3,4-tetrahydro-2,3-naphthalenediol (or 2,3-tetralindiol) and of 1,2-cyclohexanediol have been investigated. The structure of a very stable 1:1 compound (or co-crystal) of the cis and trans isomers of 2,3-tetralindiol, the existence of which has been known for nearly a century, has finally been determined. No evidence of any analogous compound between the cis and trans isomers of 1,2-cyclohexanediol has been found. The formation of solid-state compounds of stereoisomers is rare; it probably occurs only if the crystal packing of at least one of the isomers is unfavorable, e.g. if at least one of the melting points is lower than expected. Compound formation is usually unlikely because of the difficulty of simultaneously optimizing the translational spacings for both isomers, but that packing problem is avoided in the cis/trans compound of 2,3-tetralindiol because the two isomers are in very similar environments. In the structures of the individual 2,3-tetralindiol isomers there are clear conflicts between the competing packing requirements of the 1,2-diol moiety and the aromatic ring system; these conflicts are resolved better in the co-crystal than in the structures of the individual isomers. [source] Theoretical studies on high-valent manganese porphyrins: Toward a deeper understanding of the energetics, electron distributions, and structural features of the reactive intermediates of enzymatic and synthetic manganese-catalyzed oxidative processesISRAEL JOURNAL OF CHEMISTRY, Issue 1 2000Abhik Ghosh We present here a relatively comprehensive theoretical study, based on nonlocal density functional theory calculations, of the energetics, electron distributions, and structural features of the low-lying electronic states of various high-valent intermediates of manganese porphyrins. Two classes of molecules have been examined: (a) compounds with the general formula [(P)MnX2]0 (P = porphyrin; X = F, Cl, PF6) and (b) high-valent manganese-oxo species. For [(P)Mn(PF6)2]0, the calculations reveal a number of nearly equienergetic quartet and sextet states as the lowest states, consistent with experimental results on a comparable species, [(TMP)Mn(ClO4)2]0 (TMP = tetramesitylporphyrin). In contrast, [(P)MnCl2]0 and [(P)MnF2]0 have a single well-defined S = 3/2 Mn(IV) ground state, again in agreement with experiment, with the three unpaired spins largely concentrated (>90%) on the manganese atom. Manganese(IV)-oxo porphyrins have an S = 3/2 ground state, with the three unpaired spins distributed approximately 2.3:0.7 between the manganese and oxygen atoms. The metal-to-oxygen spin delocalization, as measured by the oxygen spin population, for MnIV = O porphyrins is less than, but still qualitatively similar to, that in analogous iron(IV)-oxo intermediates, indicating that the MnIV = O bond is significantly weaker than the FeIV = O bond in an analogous molecule. Thus, the optimized metal,oxygen bond distances are 1.654 and 1.674 Å for (P)FeIV(O)(Py) and (P)MnIV(O)(Py), respectively (Py = pyridine). This is consistent with the experimental observation that MnIV = O stretching frequencies are over 10% lower than FeIV = O stretching frequencies for analogous compounds. For [(P)Mn(O)(PF6)]0, [(P)Mn(O)(Py)]+, and [(P)Mn(O)(F)]0, the ground states clearly correspond to a (dxy)2 Mn(V) configuration and the short Mn,O distances of 1.541, 1.546, and 1.561 Å for the three compounds, respectively, reflect the formal triple bond character of the Mn,O interaction. Interestingly, the corresponding Mn(IV)-oxo porphyrin cation radical states are calculated to be a few tenths of an electrovolt higher than the Mn(V) ground states, suggesting that the Mn(IV)-oxo porphyrin cation radicals are not likely to exist as ground-state species. [source] Insecticidal activities of secondary metabolites of endophytic Pencillium sp. in Derris elliptica BenthJOURNAL OF APPLIED ENTOMOLOGY, Issue 8 2005M. Y. Hu Abstract:, A strain of endophytic Pencillium sp., which might produce rotenone or its analogues and showed bioactivity against aphids, was isolated from the fresh roots of Derris elliptica Benth. A total of 12 fractions, isolated from the chloroform extract of endophytic Pencillium sp. mycelia by silica gel column, were tested by bioassay and high-performance liquid chromatography (HPLC), and the more bioactive fractions were found to be D, E and J. Against the adult turnip aphid, Lipaphis erysimi, by dipping at a concentration of 1 mg/ml, the corrected mortalities of fraction D, E and J were 57.68, 63.28 and 69.74% after 48 h of treatment respectively. The three fractions also showed strong antifeeding activity against third instar larvae of Plutella xylostella in a laboratory bioassay. One absorption peak was detected in the HPLC picture of fraction D, it had a similar retention time as that of rotenone, and the chemical constituent, related to the absoption peak, had the same ultraviolet absorption picture as that of rotenone. Then it could be further concluded that the bioactive compounds in the fraction D could be rotenone or its analogous compounds. [source] 2-Amino-4-chloro-5-formyl-6-[methyl(2-methylphenyl)amino]pyrimidine and 2-amino-4-chloro-5-formyl-6-[(2-methoxyphenyl)methylamino]pyrimidine are isostructural and form hydrogen-bonded sheets of R22(8) and R66(32) ringsACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Jorge Trilleras 2-Amino-4-chloro-5-formyl-6-[methyl(2-methylphenyl)amino]pyrimidine, C13H13ClN4O, (I), and 2-amino-4-chloro-5-formyl-6-[(2-methoxyphenyl)methylamino]pyrimidine, C13H13ClN4O2, (II), are isostructural and essentially isomorphous. Although the pyrimidine rings in each compound are planar, the ring-substituent atoms show significant displacements from this plane, and the bond distances provide evidence for polarization of the electronic structures. In each compound, a combination of N,H...N and N,H...O hydrogen bonds links the molecules into sheets built from centrosymmetric R22(8) and R66(32) rings. The significance of this study lies in its observation of the isostructural nature of (I) and (II), and in the comparison of their crystal and molecular structures with those of analogous compounds. [source] Carbohydrate-derived alkylcobalt carbonyl: {[(1,2:5,6-Di-O,O-isopropylidene-,-D-glucofuranos-3-yl)oxycarbonyl]methyl}cobalt tricarbonyl triphenylphosphineCHIRALITY, Issue 8 2001Claudia Zucchi Abstract A carbohydrate-derivative alkylcobalt carbonyl, {[(1,2:5,6-di-O,O-isopropylidene-,-D-glucofuranos-3-yl)oxycarbonyl]methyl}cobalt tricarbonyl triphenylphosphine (3) was prepared and characterized by IR, NMR, and CD spectra, as well as by X-ray diffraction. The supramolecular chemistry in the crystalline P212121 (chiral) phase and in solution was analyzed and compared. The bulky carbohydrate-based ligand stabilized one chiral conformation, which, however, is less ordered than for analogous compounds with more flexible and less bulky chiral groups. Intermolecular, H-bond interactions are more important in the P212121 phase of complex 3 than at other analogous compounds. Chirality 13:458,464, 2001. © 2001 Wiley-Liss, Inc. [source] | ||||||||||