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Titolo:
2-DIMENSIONAL H-1-NMR STUDIES ON OCTAHEDRAL NICKEL(II) COMPLEXES
Autore:
HOLZ RC; EVDOKIMOV EA; GOBENA FT;
Indirizzi:
UTAH STATE UNIV,DEPT CHEM & BIOCHEM LOGAN UT 84322
Titolo Testata:
Inorganic chemistry
fascicolo: 13, volume: 35, anno: 1996,
pagine: 3808 - 3814
SICI:
0020-1669(1996)35:13<3808:2HSOON>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAGNETIC-PROPERTIES; SPECTROSCOPIC CHARACTERIZATION; AEROMONAS AMINOPEPTIDASE; LEUCINE AMINOPEPTIDASE; SUPEROXIDE-DISMUTASE; UREASE; SITE; CARBOXYPEPTIDASE; H-1-NMR; COBALT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
R.C. Holz et al., "2-DIMENSIONAL H-1-NMR STUDIES ON OCTAHEDRAL NICKEL(II) COMPLEXES", Inorganic chemistry, 35(13), 1996, pp. 3808-3814

Abstract

The dinucleating ligand ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N',-tetrakis[(2-ethylbenzimidazoyl)] (EGTB-Et; 1) was used to synthesize the dinuclear Ni(II) tetraacetonitrile complex cation [Ni-2(EGTB-Et)(CH3-CN)(4)](2+)(2): triclinic space group P(1)over-bar (a=12.273(5) angstrom, b=12.358(7) angstrom, c=12.561(6) angstrom, alpha=90.43(4) degrees, beta=110.26(3) degrees, gamma=99.21(4) degrees, and Z=1). The structure shows two identical octahedral Ni(II) centers each bound to two benzimidazole ring nitrogen atoms, one amine nitrogen atom, an ether oxygen atom, and two acetonitrile nitrogen atoms. The Ni(II) ions are tethered together by a diethyl ether linkage with a crystallographic center of inversion between the methylene carbons of this bridge. The Ni-Ni separation in 2 is 7.072 angstrom. The mononuclear Ni(II)complex cation [Ni(Bipy)(2)(OAc)](+)(3) (Bipy=bipyridine) was synthesized and crystallographically characterized: monoclinic space group P2(I)/c (a=9.269(4) angstrom, b=8.348(4) angstrom, c=14.623(7) angstrom,and beta=102.46(4) degrees, Z=2). The Ni(II) ions in 3 adopts a distorted octahedral geometry and is bound to four bipyridine ring nitrogenatoms and two carboxylate oxygen atoms. The average Ni-Ni and Ni-O distances are 2.062 and 2.110 angstrom. The electronic absorption spectra of both 2 and 3 were recorded in acetonitrile solution and are consistent with octahedral coordination geometries about the Ni(II) ions with Racah parameters of 840 and 820 cm(-1), respectively. Both one- anddimensional two-dimensional H-1 NMR techniques were used to assign the observed hyperfine shifted H-1 NMR resonances of of 2 and 3 in acetonitrile solution. Clear COSY cross signals are observed between the aromatic protons of both the benzimidazole and pyridine protons of 2 and3, respectively. The use of 2D NMR methods to assign inequivalent aromatic protons rather than synthetic methods such as substitution or deuteration are discussed.

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Documento generato il 01/12/20 alle ore 19:56:43