Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/103501
Type: Artigo de periódico
Title: Synthesis And Crystal Structure Of 2,4-dihydro-4-[(5-hydroxy-3-methyl-1-phenyl-1h-pyrazol-4-yl)imino]-5-met Hyl-2-phenyl-3h-pyrazol-3-one And Its Copper(ii) Complex
Author: Cerchiaro G.
Da Costa Ferreira A.M.
Teixeira A.B.
Magalhaes H.M.
Cunha A.C.
Ferreira V.F.
Santos L.S.
Eberlin M.N.
Skakle J.M.S.
Wardell S.M.S.V.
Wardell J.L.
Abstract: 2-Diazo-3-methyl-1-phenyl-5-pyrazolone (2) and 2,4-dihydro-4-[(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)imino]-5-met hyl-2-phenyl-3H-pyrazol-3-one (3) were obtained in a one-pot reaction from 3-methyl-1-phenylpyrazol-5-one (1), mesyl azide, and K2CO3 in MeOH or CH2Cl2 solution. NMR, IR and ESI mass spectra as well as the crystal structure are reported for red colored 3. The crystal structure determined at 150 K reveals that the corresponding bonds in the two phenylpyrazol-5-one moieties in each of the two independent "U" shaped molecules have essentially the same lengths, with an extensive delocalization in the central O-C-C-N-C-C-O fragment of the molecule. In particular, the hydrogen atom, formally a part of a hydroxyl group, is found near-midway [O1-HY and O11-HY = 1.24(4) and 1.19(4) Å, in molecule 1, and O21-HX and O31-HY = 1.203(4) and 1.19(4) Å, in molecule 2] between the two oxygen atoms (formally in a carbonyl and a hydroxy group), with near linear O-H-O bond angles of 173.8(4)° and 172.7(4)° in the two independent molecules. All C-O bond lengths are in the narrow range of 1.271(3)-1.288(3) Å. Further, since this compound shows different coordinating groups, its binding ability towards copper(II) ions was investigated. A dark red complex 4, obtained by reaction of 3 with copper(II) ions at stoichiometric ratio, was characterized as a neutral 1:1 species, [3:CuCl2], involving tautomeric forms, by ESI-MS, ESI-MS/MS, IR, UV/Vis and EPR spectra. Interestingly, copper coordination to ligand 3 occurs solely by oxygen atoms, in spite of the presence of nitrogen donor centers. The deprotonation of 4 was monitored by UV/Vis, and a corresponding pKa value was determined as (5.6 ± 0.2). © 2006 Elsevier Ltd. All rights reserved.
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Rights: fechado
Identifier DOI: 10.1016/j.poly.2006.01.002
Address: http://www.scopus.com/inward/record.url?eid=2-s2.0-33744899562&partnerID=40&md5=f644c8f843428151f0fcd5579a3624e4
Date Issue: 2006
Appears in Collections:Unicamp - Artigos e Outros Documentos

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