A step beyond the Feltham-Enemark notation: spectroscopic and correlated ab initio computational support for an antiferromagnetically coupled M(II)-(NO)- description of Tp*M(NO) (M = Co, Ni).
J Am Chem Soc
; 133(46): 18785-801, 2011 Nov 23.
Article
en En
| MEDLINE
| ID: mdl-22047035
ABSTRACT
Multiple spectroscopic and computational methods were used to characterize the ground-state electronic structure of the novel {CoNO}(9) species Tp*Co(NO) (Tp* = hydro-tris(3,5-Me(2)-pyrazolyl)borate). The metric parameters about the metal center and the pre-edge region of the Co K-edge X-ray absorption spectrum were reproduced by density functional theory (DFT), providing a qualitative description of the Co-NO bonding interaction as a Co(II) (S(Co) = 3/2) metal center, antiferromagnetically coupled to a triplet NO(-) anion (S(NO) = 1), an interpretation of the electronic structure that was validated by ab initio multireference methods (CASSCF/MRCI). Electron paramagnetic resonance (EPR) spectroscopy revealed significant g-anisotropy in the S = ½ ground state, but the linear-response DFT performed poorly at calculating the g-values. Instead, CASSCF/MRCI computational studies in conjunction with quasi-degenerate perturbation theory with respect to spin-orbit coupling were required for obtaining accurate modeling of the molecular g-tensor. The computational portion of this work was extended to the diamagnetic Ni analogue of the Co complex, Tp*Ni(NO), which was found to consist of a Ni(II) (S(Ni) = 1) metal center antiferromagnetically coupled to an S(NO) = 1 NO(-). The similarity between the Co and Ni complexes contrasts with the previously studied Cu analogues, for which a Cu(I) bound to NO(0) formulation has been described. This discrepancy will be discussed along with a comparison of the DFT and ab initio computational methods for their ability to predict various spectroscopic and molecular features.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Compuestos Organometálicos
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Teoría Cuántica
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Cobalto
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Hierro
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Magnetismo
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Níquel
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Óxido Nítrico
Tipo de estudio:
Prognostic_studies
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Qualitative_research
Idioma:
En
Revista:
J Am Chem Soc
Año:
2011
Tipo del documento:
Article
País de afiliación:
Alemania