18362-64-6Relevant articles and documents
PROCESSES FOR PREPARING β-DIKETONE COMPOUND, METAL COMPLEX THEREOF AND METALLIC COMPOUND
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Page/Page column 24-25, (2008/06/13)
Disclosed is a process for preparing a β-diketone compound such as 2,6-dimethyl-3,5-heptanedione, which comprises reacting an ester compound such as an alkyl isobutyrate with a ketone compound such as 3-methylbutanone in the presence of an alkali metal alkoxide as a catalyst. The process comprises a step 1 in which an ester compound CR1R2R3COOQ is reacted with a ketone compound CR4R5R6COCH2R7 using an alkali metal alkoxide catalyst to give a β-diketone compound CR1R2R3COCHR4R5R6. (In the formulae, R7 is hydrogen or an alkyl group of 1 to 4 carbon atoms while others are each independently hydrogen or an alkyl group of 1 to 3 carbon atoms, and at least one of R1 to R6 is hydrogen.)
The crystal structure of 3,5-diisopropyl-4-nitropyrazole from X-ray powder diffraction data
Ochando,Amigó,Rius,Lou?r,Fontenas,Elguero
, p. 11 - 17 (2007/10/03)
The crystal structure of 3,5-diisopropyl-4-nitropyrazole, 3c, has been determined by a Patterson Search method from laboratory X-ray powder diffraction data. The crystal data are: monoclinic symmetry with the unit-cell parameters a = 19.530(5), b = 6.485(1) and c = 17.937(3) ?,β = 100.32(1)°, space group 12/a, C9H15N3O2, Z = 8, 293 K. After indexing the powder pattern by two methods, the unit-cell parameters found were refined by a least-squares technique. A whole pattern-fitting program was used to extract the integrated intensities. The structure was solved taking a related compound as a search model and the final Rietveld refinement converged to Rwp = 0.1971 and Rp = 0.1437. The structure presents a dimer conformation between N atoms through a hydrogen bond.
A new model for dioxygen binding in hemocyanin. Synthesis, characterization, and molecular structure of the μ-η2:η2 peroxo dinuclear copper(II) complexes, [Cu(HB(3,5-R2pz)3)]2(O2) (R = i-Pr and Ph)
Kitajima, Nobumasa,Fujisawa, Kiyoshi,Fujimoto, Chisato,Moro-oka, Yoshihiko,Hashimoto, Shinji,Kitagawa, Teizo,Toriumi, Koshiro,Tatsumi, Kazuyuki,Nakamura, Akira
, p. 1277 - 1291 (2007/10/02)
The synthesis and characterization of μ-η2:η2 peroxo dinuclear copper(II) complexes which show many similarities to oxyhemocyanin (or oxytyrosinase) in their physicochemical properties are presented. The low-temperature reaction of a di-μ-hydroxo copper(II) complex [Cu(HB(3,5-i-Pr2pz)3)]2(OH)2 (8) with H2O2 gave a μ-peroxo complex [Cu(HB(3,5-i-Pr2pz)3)]2(O2) (6). Complex 6 was also prepared by dioxygen addition to a copper(I) complex Cu(HB(3,5-i-Pr2pz)3) (9). The preparation of an analogous peroxo complex [Cu(HB(3,5-Ph2pz)3)]2(O2) (7) was accomplished by the similar dioxygen treatment of a copper(I) acetone adduct Cu(Me2CO)(HB(3,5-Ph2pz)3) (10). The reaction of 6 with CO or PPh3 causes release of dioxygen, resulting in formation of the corresponding copper(I) adduct, Cu(CO)(HB(3,5-i-Pr2pz)3) (11) or Cu(PPh3)(HB(3,5-i-Pr2pz)3) (12). Crystallography was performed for 6-6(CH2Cl2), 8-1.5(CH2Cl2), and 11. Compound 6-6(CH2Cl2) crystallizes in the monoclinic space group C2/c with a = 26.36 (2) A?, b = 13.290 (4) A?, c = 29.29 (2) A?, β= 114.59 (6)°, V = 7915 (9) A?3, and Z = 4. The refinement converged with the final R (Rw) value, 0.101 (0.148), for 3003 reflections with F ≥ 3σ(Fo). Compound 8-1.5(CH2Cl2) crystallizes in the triclinic space group P1? with a = 16.466 (4) A?, b = 16.904 (5) A?, c = 14.077 (3) A?, a = 112.92 (2)°, β= 99.21 (2)°, γ = 90.76 (2)°, V = 3550 (2) A?3, Z = 2, and the final R (Rw) factor, 0.083 (0.105), for 7226 reflections with F ≥ 3σ(Fo). Compound 11 crystallizes in the monoclinic space group, P21/a with a = 16.595 (4) A?, b = 19.154 (4) A?, c = 10.359 (2) A?, β= 106.65 (2)°, V = 3155 (1) A?3, Z = 4, and the final R (Rw) value 0.083 (0.074) for 5356 reflections with F ≥ 3σ(Fo). The X-ray analysis of 6-6(CH2Cl2) definitely established the μ-η2:η2 coordination structure of the peroxide ion for the first time. This unusual side-on structure is entirely novel for a d-block element transition-metal-dioxygen complex. Both 6 and 7 show remarkable characteristics which are very similar to those known for oxyhemocyanin and oxytyrosinase. Complex 6: diamagnetic; ν(O-O), 741 cm-1; UV-vis, 349 nm (ε, 21 000), 551 nm (ε, 790); Cu-Cu, 3.56 A?. Complex 7: diamagnetic, ν(O-O), 759 cm-1; UV-vis, 355 nm (ε, 18 000), 542 nm (ε, 1040). These properties are all consistent with those of an analogous complex, [Cu(HB(3,5-Me2pz)3)]2(O2) (5), of which the characterization and reactivities were reported already (Kitajima, N., et al. J. Am. Chem. Soc. 1990, 112, 6402; 1991, 113, 5664). The magnetic and spectroscopic features of 5-7 and their biological relevance are discussed in detail. Furthermore, simple interpretation of the electronic state of the N3Cu(O22-)CuN3 chromophore is provided based on extended Hu?ckel MO calculations. The close resemblance between the properties of μ-η2:η2 peroxo complexes 5-7 and oxyhemocyanin led us to propose a new model for dioxygen binding in hemocyanin; dioxygen is simply bound between the two copper ions in the μ-η2:η2 mode. With this structural model; the existence of an endogenous bridging ligand, which has been generally supposed to account for the diamagnetism of oxyhemocyanin, is no longer necessary.
