Axial ligand influence on geometries, charge distributions and electronic structures of iron tetraazamacrocycle [Fe((II))TIM(X)(Y)](2+) complexes assessed by Density Functional Theory


Autoria(s): HAIDUKE, Roberto Luiz Andrade; RODRIGUES-FILHO, Ubirajara Pereira
Contribuinte(s)

UNIVERSIDADE DE SÃO PAULO

Data(s)

20/10/2012

20/10/2012

2011

Resumo

We employed the Density Functional Theory along with small basis sets, B3LYP/LANL2DZ, for the study of FeTIM complexes with different pairs of axial ligands (CO, H(2)O, NH(3), imidazole and CH(3)CN). These calculations did not result in relevant changes of molecular quantities as bond lengths, vibrational frequencies and electronic populations supporting any significant back-donation to the carbonyl or acetonitrile axial ligands. Moreover, a back-donation mechanism to the macrocycle cannot be used to explain the observed changes in molecular properties along these complexes with CO or CH(3)CN. This work also indicates that complexes with CO show smaller binding energies and are less stable than complexes with CH(3)CN. Further, the electronic band with the largest intensity in the visible region (or close to this region) is associated to the transition from an occupied 3d orbital on iron to an empty pi* orbital located at the macrocycle. The energy of this Metal-to-Ligand Charge Transfer (MLCT) transition shows a linear relation to the total charge of the macrocycle in these complexes as given by Mulliken or Natural Population Analysis (NPA) formalisms. Finally, the macrocycle total charge seems to be influenced by the field induced by the axial ligands. (C) 2011 Elsevier Ltd. All rights reserved.

CNPq (The National Council for Scientific and Technological Development)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Identificador

POLYHEDRON, v.30, n.8, p.1396-1403, 2011

0277-5387

http://producao.usp.br/handle/BDPI/31777

10.1016/j.poly.2011.02.036

http://dx.doi.org/10.1016/j.poly.2011.02.036

Idioma(s)

eng

Publicador

PERGAMON-ELSEVIER SCIENCE LTD

Relação

Polyhedron

Direitos

restrictedAccess

Copyright PERGAMON-ELSEVIER SCIENCE LTD

Palavras-Chave #Iron tetraazamacrocycle complexes #d(6) low spin complexes #Density Functional Theory #Back-donation #Metal-to-Ligand Charge Transfer transition #EFFECTIVE CORE POTENTIALS #INCLUDING CARBON-MONOXIDE #MOLECULAR CALCULATIONS #POPULATION ANALYSIS #MACROCYCLIC LIGANDS #EXCITATION-ENERGIES #AQUEOUS-SOLUTION #WAVE FUNCTIONS #ATOMS #PHOTOCHEMISTRY #Chemistry, Inorganic & Nuclear #Crystallography
Tipo

article

original article

publishedVersion