Metal complexes of pyrazole-4,5-dione-4-oximes: crystallographic characterization and their reactions with dimethyl acetylenedicarboxylate

Barjesteh, Hangameh; Chakrabarti, Jayatibha; Charalambous, J.; Carugo, Oliviero; Castellani, Carla Bisi

doi:10.1016/0277-5387(95)00369-x

Cited by 6 publications

(5 citation statements)

References 14 publications

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“…For complexes 1 , 3 , and 4 with the oxime-containing ligands, infrared absorption peaks assigned to the ν(N−O) stretching mode of the oxime groups were found to be noticeably shifted to higher frequencies as compared to the spectra of the corresponding free ligands (Δν = 35 ( 1 ), 27 ( 3 ), 157 and 140 cm −1 ( 4 )). This clearly suggests coordination of the oxime group via the nitrogen atom, as observed in the solid-state structures of 1 and 4 (see below). , …”

Section: Resultsmentioning

confidence: 53%

Efficient Catalytic Phosphate Ester Cleavage by Binuclear Zinc(II) Pyrazolate Complexes as Functional Models of Metallophosphatases

et al. 2009

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A series of dizinc(II) complexes based on the pyrazolate ligands 3-[(1E)-N-hydroxyethanimidoyl]-4-methyl-1H-pyrazole-5-carboxylic acid (H(3)L(1)), (1E,1'E)-1,1'-(4-methyl-1H-pyrazole-3,5-diyl)diethanone dihydrazone (HL(2)), (E,E)-(4-methyl-1H-pyrazole-3,5-diyl)bis(methylmethanone) dioxime (H(3)L(3)), (E,E)-(4-phenyl-1H-pyrazole-3,5-diyl)bis(phenylmethanone) dioxime (H(3)L(4)), and 1H-pyrazole-3,5-dicarboxylic acid (H(3)L(5)) have been synthesized and investigated as functional models of phosphoesterases, focusing on correlations between the hydrolytic activity and molecular parameters of the bimetallic core. Speciation of the various dizinc complexes in solution has been determined potentiometrically, and the structures in the solid state have been established by X-ray crystallography. The hydrolysis of two phosphoesters, an RNA model 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) and the pesticide paraoxon-ethyl (POE), promoted by the dinuclear phosphoesterase model complexes has been investigated in DMSO/buffered water (1:1) at 50 degrees C as a function of complex concentration, substrate concentration, and pH. Drastic differences in the hydrolytic activities of [Zn(2)(HL(1))(2)](0), [Zn(2)(L(2))(2)](2+), [Zn(2)(H(2)L(3))(2)](2+), and [Zn(2)(HL(5))(2)](2-) are observed and can be attributed to molecular peculiarities. Pyrazolate-bridged dinuclear zinc(II) complexes seem to provide a sufficient number of coordination sites for both activating the substrate and generating the nucleophile, where the phosphate esters are preferentially bound in a bidentate bridging fashion (in the case of HPNP) and in a monodentate fashion (in the case of POE).

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Section: Resultsmentioning

confidence: 53%

Efficient Catalytic Phosphate Ester Cleavage by Binuclear Zinc(II) Pyrazolate Complexes as Functional Models of Metallophosphatases

et al. 2009

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“…On the other hand, Barjesteh et al (1996) described the crystal structure of metal complexes obtained from 1-phenyl-3-methyl-and 1,3-dimethyl-4-(hydroxyimino)pyrazol-5-one, and they suggested that the complexes have an oximino structure; however, a closer analysis of the bond lengths seems to point towards a 4-nitroso complex in both cases. The structure of 4-[(N-benzoyloxycarbonylvalyl)oxyimino]-3methyl-1-phenyl-2-pyrazolin-5-one has also been described (Bertolasi et al, 1978), but in this case the oximino structure is locked by the acyl group.…”

Section: Commentmentioning

confidence: 99%

An oximino tautomer of 1-n-decyl-4-hydroxyimino-3-methyl-1H-pyrazol-5(4H)-one

et al. 2006

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The title compound, C14H25N3O2, consists of a five-membered heterocyclic ring to which a pendant decyl group is attached. The oximino tautomeric character of the molecule is clearly defined by the distribution of well defined double bonds in the heterocycle region (one C=O and two C=N). The most conspicuous packing interaction is the strong intermolecular hydrogen bond linking the oximino OH group and the carbonyl O atom to define broad planar hydrophilic strips running along the unique b axis. The alkyl chains adopt a fully extended conformation and lie almost at right angles to these one-dimensional structures, defining their hydrophobic counterpart.

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“…The title compound (Fig. 1) is an ortho-hydroxynitroso aromatic compound, which may have a role in metal complexation and in photochromic spirooxazines (Barjesteh et al, 1996;Patel et al, 2005Patel et al, , 2010. A tautomeric disorder was observed in this structure (Enchev et al, 2003;Terent'ev & Stankyavichyus, 1988).…”

Section: S1 Commentmentioning

confidence: 92%

“…For information on tautomerization in ortho-hydroxynitroso aromatic compounds, see: Enchev et al (2003); Terent'ev & Stankyavichyus (1988). For the role of ortho-hydroxynitroso aromatic compounds in metal complexation and in photochromic spirooxazines, see: Barjesteh et al (1996); Patel et al (2005Patel et al ( , 2010. For the spectrochemical characterization of the title compound, see: Kumar et al (2009).…”

Section: Related Literaturementioning

confidence: 99%

Tautomerism in 10-(hydroxyimino)phenanthren-9-one

Patel

Benedict

2012

Acta Cryst E

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Key indicators: single-crystal X-ray study; T = 90 K; mean (C-C) = 0.004 Å; disorder in main residue; R factor = 0.036; wR factor = 0.099; data-to-parameter ratio = 6.4.In the title compound, C 14 H 9 NO 2 , a static disorder exists between the keto-oxime and hydroxy-nitroso tautomers, in an approximate ratio of 4.6:1, based on refined occupancies for disordered parts. No intermolecular hydrogen bonding is present in the crystal structure. Instead, both tautomers exhibit similar intramolecular O-HÁ Á ÁO hydrogen bonds. Related literature

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Metal complexes of pyrazole-4,5-dione-4-oximes: crystallographic characterization and their reactions with dimethyl acetylenedicarboxylate

Cited by 6 publications

References 14 publications

Efficient Catalytic Phosphate Ester Cleavage by Binuclear Zinc(II) Pyrazolate Complexes as Functional Models of Metallophosphatases

Efficient Catalytic Phosphate Ester Cleavage by Binuclear Zinc(II) Pyrazolate Complexes as Functional Models of Metallophosphatases

An oximino tautomer of 1-n-decyl-4-hydroxyimino-3-methyl-1H-pyrazol-5(4H)-one

Tautomerism in 10-(hydroxyimino)phenanthren-9-one

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