title: Structural, spectroscopic, and electrochemical behavior of trans-phenolato cobalt(III) complexes of asymmetric NN'O ligands as archetypes for metallomesogens.
abstract: In order to understand and predict structural, redox, magnetic, and optical properties of more complex and potentially mesogenic electroactive compounds such as [Co(III)(L(t-BuLC))2]ClO4 (1), five archetypical complexes of general formula [Co(III)(L(RA))2]ClO4, where R = H (2), tert-butyl (3), methoxy (4), nitro (5), and chloro (6), were obtained and studied by means of several spectrometric, spectroscopic, and electrochemical methods. The complexes 2, 4, and 6 were characterized by single-crystal X-ray diffraction, and show the metal center in an approximate D2h symmetry. Experimental results support the fact that the electron donating or withdrawing nature of the phenolate-appended substituents changes dramatically the redox and spectroscopic properties of these compounds. The 3d6 electronic configuration of the metal ion dominates the overall geometry adopted by these compounds with the phenolate rings occupying trans positions to one another. Formation of phenoxyl radicals has been observed for 1, 3, and 6, but irreversible ligand oxidation takes place upon bulk electrolysis. These data were compared to detailed B3LYP/6-31G (d)-level computational calculations and have been used to account for the results observed. A comparison between compound 1 and archetype 3, validates the approach of using archetypical models to study metal-containing soft materials.
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, MI 48202, USA.
authors.forename: Rajendra
authors.initials: R
authors.lastname: Shakya
authors.forename: Camille
authors.initials: C
authors.lastname: Imbert
authors.forename: Hrant P
authors.initials: HP
authors.lastname: Hratchian
authors.forename: Mauricio
authors.initials: M
authors.lastname: Lanznaster
authors.forename: Mary Jane
authors.initials: MJ
authors.lastname: Heeg
authors.forename: Bruce R
authors.initials: BR
authors.lastname: McGarvey
authors.forename: Marco
authors.initials: M
authors.lastname: Allard
authors.forename: H Bernhard
authors.initials: HB
authors.lastname: Schlegel
authors.forename: Claudio N
authors.initials: CN
authors.lastname: Verani