Metrical Oxidation States of 2-Amidophenoxide and Catecholate Ligands: Structural Signatures of Metal–Ligand π Bonding in Potentially Noninnocent Ligands
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- 19 January 2012
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 51 (3) , 1251-1260
Abstract
Catecholates and 2-amidophenoxides are prototypical “noninnocent” ligands which can form metal complexes where the ligands are best described as being in the monoanionic (imino)semiquinone or neutral (imino)quinone oxidation state instead of their closed-shell dianionic form. Through a comprehensive analysis of structural data available for compounds with these ligands in unambiguous oxidation states (109 amidophenolates, 259 catecholates), the well-known structural changes in the ligands with oxidation state can be quantified. Using these correlations, an empirical “metrical oxidation state” (MOS) which gives a continuous measure of the apparent oxidation state of the ligand can be determined based on least-squares fitting of its C–C, C–O, and C–N bond lengths to this single parameter (a simple procedure for doing so is provided via a spreadsheet in the Supporting Information). High-valent d0 metal complexes, particularly those of vanadium(V) and molybdenum(VI), have ligands with unexpectedly positive, and generally nonintegral, MOS values. The structural effects in these complexes are attributed not to electron transfer, but rather to amidophenoxide- or catecholate-to-metal π bonding, an interpretation supported by the systematic variation of the MOS values as a function of the degree of competition with the other π-donating groups in the structures.Keywords
This publication has 55 references indexed in Scilit:
- Preface: Forum on Redox-Active LigandsInorganic Chemistry, 2011
- Electronic characteristics of an extensive series of ruthenium complexes with the non-innocent o-benzoquinonediimine ligand: A pedagogical approachCoordination Chemistry Reviews, 2010
- Radical Ligands Confer Nobility on Base-Metal CatalystsScience, 2010
- Intermetallic Communication in Titanium(IV) FerrocenyldiketonatesInorganic Chemistry, 2009
- Four‐Electron Oxidative Formation of Aryl Diazenes Using a Tantalum Redox‐Active Ligand ComplexAngewandte Chemie International Edition, 2008
- Catalytic Reactivity of a Zirconium(IV) Redox-Active Ligand Complex with 1,2-DiphenylhydrazineJournal of the American Chemical Society, 2008
- C−C Bond-Forming Reductive Elimination from a Zirconium(IV) Redox-Active Ligand ComplexJournal of the American Chemical Society, 2006
- o-Iminobenzosemiquinonato Complexes of Mn(III) and Mn(IV). Synthesis and Characterization of [MnIII(LISQ)2(LAP)] (St = 1) and [MnIV(LISQ)2(LAP-H)] (St = 1/2)Inorganic Chemistry, 2002
- Electronic Structure of Bis(o-iminobenzosemiquinonato)metal Complexes (Cu, Ni, Pd). The Art of Establishing Physical Oxidation States in Transition-Metal Complexes Containing Radical LigandsJournal of the American Chemical Society, 2001
- Theoretical study of o-quinone complexes of chromium and vanadiumInorganic Chemistry, 1982