Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/xmlui/handle/123456789/19949
Title: Different manifestations of enhanced pi-acceptor ligation at every redox level of [Os(9-OP)L-2](n), n=2+, +, 0, - (9-OP-=9-oxidophenalenone and L = bpy or pap)
Authors: HAZARI, AS
PARETZKI, A
FIEDLER, J
ZALIS, S
KAIM, W
LAHIRI, GK
Keywords: Density-Functional Theory
Beta-Diketonate Ligand
Electronic-Structures
Non-Innocence
Excitation-Energies
Radical Complexes
Transition-Metal
Ground-State
Molecules
Epr
Issue Date: 2016
Publisher: ROYAL SOC CHEMISTRY
Citation: DALTON TRANSACTIONS,45(45)18241-18251
Abstract: The title complexes were isolated as structurally characterised compounds [Os-II(9-OP)L-2]ClO4, L = 2,2'-bipyridine (bpy) or 2-phenylazopyridine (pap), and were compared with ruthenium analogues. A reversible one-electron oxidation and up to three reduction processes were observed by voltammetry (CV, DPV) and spectroelectrochemistry (UV-vis-NIR, partially EPR). Supporting calculations (DFT, TD-DFT) were used to assess the oxidation state combinations of the different redox active ligands and of the metal, revealing the effects of Os versus Ru exchange and of bpy versus pap acceptor ligation. Several unexpected consequences of these variations were observed for members of the new osmium-containing redox series. Remarkably, the EPR results exhibit a clear dichotomy between the complex ion [Os-III(9-OP-)( bpy)(2)](2+) and the radical species [Os-II(9-OP-)(pap)(2)](2+), which has not been similarly observed for the analogous [Ru-III(9-OP-)(L2)](2+) systems. This difference, unprecedented for 5d(n) systems, is attributed to the superior stabilisation of the Os-II state by the strongly pi-accepting pap ligands. The reduced forms [Os-II(9-OP-)(pap(-))(pap)] and [OsII(9-OP-)(pap(-))(2)](-) exhibit strong inter-ligand interactions, leading to spin isomers and electron hopping.
URI: http://dx.doi.org/10.1039/c6dt03764j
http://localhost:8080/xmlui/handle/123456789/19949
ISSN: 1477-9226
1477-9234
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