Structure and Spectroelectrochemical Response of Arene–Ruthenium and Arene–Osmium Complexes with Potentially Hemilabile Noninnocent Ligands

Nine of the compounds [M(L2–)(p-cymene)] (M = Ru, Os, L2– = 4,6-di-tert-butyl-N-aryl-o-amidophenolate) were prepared and structurally characterized (Ru complexes) as coordinatively unsaturated, formally 16 valence electron species. On L2–-ligand based oxidation to EPR-active iminosemiquinone radical complexes, the compounds seek to bind a donor atom (if available) from the N-aryl substituent, as structurally certified for thioether and selenoether functions, or from the donor solvent. Simulated cyclic voltammograms and spectroelectrochemistry at ambient and low temperatures in combination with DFT results confirm a square scheme behavior (ECEC mechanism) involving the Ln ligand as the main electron transfer site and the metal with fractional (δ) oxidation as the center for redox-activated coordination. Attempts to crystallize [Ru(Cym)(QSMe)](PF6) produced single crystals of [RuIII(QSMe•–)2](PF6) after apparent dissociation of the arene ligand.

[1]  C. Philouze,et al.  Unprecedented redox-driven ligand ejection in nickel(II)-diiminosemiquinonate radical complexes. , 2014, Chemical communications.

[2]  Chris Orvig,et al.  Metallodrugs in medicinal inorganic chemistry. , 2014, Chemical reviews.

[3]  W. Kaim,et al.  Mixed valency of a 5d element: The osmium example , 2013 .

[4]  Vijayendran K. K. Praneeth,et al.  Redoxaktive Liganden in der Katalyse , 2012 .

[5]  V. Praneeth,et al.  Redox-active ligands in catalysis. , 2012, Angewandte Chemie.

[6]  W. Kaim,et al.  Metal(IV) Complexes [M(LN,O,S)2]n (M = Ru, Os) of a Redox‐Active o‐Amidophenolate Ligand (LN,O,S)2– with Coordinating Thioether Appendix , 2012 .

[7]  Seth N. Brown.  Metrical oxidation states of 2-amidophenoxide and catecholate ligands: structural signatures of metal-ligand π bonding in potentially noninnocent ligands. , 2012, Inorganic chemistry.

[8]  M. Beller,et al.  A convenient and general ruthenium-catalyzed transfer hydrogenation of nitro- and azobenzenes. , 2011, Chemistry.

[9]  W. Kaim,et al.  Manifestations of noninnocent ligand behavior. , 2011, Inorganic chemistry.

[10]  W. Kaim,et al.  Reversible Intramolecular Single-Electron Oxidative Addition Involving a Hemilabile Noninnocent Ligand , 2011 .

[11]  Scott R. Wilson,et al.  Oxidation of Dihydrogen by Iridium Complexes of Redox-Active Ligands , 2010 .

[12]  M. Jakupec,et al.  Maltol-derived ruthenium-cymene complexes with tumor inhibiting properties: the impact of ligand-metal bond stability on anticancer activity in vitro. , 2009, Chemistry.

[13]  J. R. Moss,et al.  Synthesis, characterization, reactivity and molecular structure of arene-osmium complexes: A new synthetic entry into (η6-arene)osmium(II) chemistry , 2009 .

[14]  A. Poddel’sky,et al.  Transition metal complexes with bulky 4,6-di-tert-butyl-N-aryl(alkyl)-o-iminobenzoquinonato ligands: Structure, EPR and magnetism , 2009 .

[15]  Anthony L. Spek,et al.  Structure validation in chemical crystallography , 2009, Acta crystallographica. Section D, Biological crystallography.

[16]  Joel S. Miller,et al.  Oxidation leading to reduction: redox-induced electron transfer (RIET). , 2009, Angewandte Chemie.

[17]  Joel S. Miller,et al.  Oxidation führt zu Reduktion – redoxinduzierter Elektronentransfer (RIET) , 2009 .

[18]  T. Rauchfuss,et al.  Redox-switched oxidation of dihydrogen using a non-innocent ligand. , 2008, Journal of the American Chemical Society.

[19]  Manfred Rudolph,et al.  Structural characterization and electrochemical behavior of oxovanadium(V) complexes with N-salicylidene hydrazides , 2007 .

[20]  John A. Weil,et al.  Electron Paramagnetic Resonance , 2006 .

[21]  R. Bergman,et al.  Safe Preparation and Purification of Sodium Tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBArF24): Reliable and Sensitive Analysis of Water in Solutions of Fluorinated Tetraarylborates , 2005 .

[22]  T. Schleid,et al.  Dreispinsystem mit neuer Wendung: ein Bis(semichinonato)kupfer‐Komplex mit nichtplanarer Konfiguration am Kupfer(II)‐Zentrum , 2005 .

[23]  W. Kaim,et al.  Three-spin system with a twist: a bis(semiquinonato)copper complex with a nonplanar configuration at the copper(II) center. , 2005, Angewandte Chemie.

[24]  I. Tavernelli,et al.  Binding of Organometallic Ruthenium(II) and Osmium(II) Complexes to an Oligonucleotide: A Combined Mass Spectrometric and Theoretical Study , 2005 .

[25]  Giovanni Scalmani,et al.  Energies, structures, and electronic properties of molecules in solution with the C‐PCM solvation model , 2003, J. Comput. Chem..

[26]  P. Floch,et al.  A Cationic 1-(2-Methylpyridine)Phosphole Cymene Ruthenium Chloride Complex as an Efficient Catalyst in the Transfer Hydrogenation of Ketones , 2003 .

[27]  Zhicong He,et al.  Could redox-switched binding of a redox-active ligand to a copper(II) centre drive a conformational proton pump gate? A synthetic model study. , 2003, Chemistry.

[28]  J. Cummings,et al.  Inhibition of cancer cell growth by ruthenium(II) arene complexes. , 2001, Journal of medicinal chemistry.

[29]  F. Matthias Bickelhaupt,et al.  Chemistry with ADF , 2001, J. Comput. Chem..

[30]  K. Wieghardt,et al.  Electronic structure of bis(o-iminobenzosemiquinonato)metal complexes (Cu, Ni, Pd). The art of establishing physical oxidation states in transition-metal complexes containing radical ligands. , 2001, Journal of the American Chemical Society.

[31]  Fr'ed'eric Naud,et al.  Hemilability of Hybrid Ligands and the Coordination Chemistry of Oxazoline-Based Systems. , 2001, Angewandte Chemie.

[32]  P. Braunstein,et al.  Hemilabilität von Hybridliganden und die Koordinationschemie von Oxazolinliganden , 2001 .

[33]  J. Gladysz,et al.  Synthesis, crystal structure, and reactions of the 17-valence-electron rhenium methyl complex [(η5-C5Me5)Re(NO)(P(4-C6H4CH3)3)(CH3)]+ B(3,5-C6H3(CF3)2)4−: experimental and computational bonding comparisons with 18-electron methyl and methylidene complexes , 2000 .

[34]  V. Barone,et al.  Toward reliable density functional methods without adjustable parameters: The PBE0 model , 1999 .

[35]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[36]  E. Corey,et al.  A Novel Chiral Super-Lewis Acidic Catalyst for Enantioselective Synthesis , 1996 .

[37]  D. Darensbourg,et al.  CHROMIUM TRICARBONYL CATECHOLATE DERIVATIVES. STRUCTURAL AND REACTIVITY STUDIES OF 16-ELECTRON COMPLEXES , 1995 .

[38]  D. Craig,et al.  Complexes of New Electrochemically-Active p-Quinonyl-/p-hydroquinonylphosphines: Multiple Electron/Proton Transfer Reactions and Electrochemical/pH Control of p-Quinonyl-/p-Hydroquinonyl o-Oxygen Atom Coordination , 1995 .

[39]  M. Daněk,et al.  Simple construction of an infrared optically transparent thin-layer electrochemical cell: Applications to the redox reactions of ferrocene, Mn2(CO)10 and Mn(CO)3(3,5-di-t-butyl-catecholate)− , 1991 .

[40]  A. Vlček,et al.  Oxidative substitution of pentacarbonylmanganese(1-) by 3,5-di-tert-butyl-1,2-benzoquinone. Synthesis and characterization of the unsaturated Mn(CO)3(DBCat)- anion , 1990 .

[41]  W. Kaim.  The transition metal coordination chemistry of anion radicals , 1987 .

[42]  T. Rauchfuss,et al.  Metal complexes of hemilabile ligands. Reactivity and structure of dichlorobis(o-(diphenylphosphino)anisole)ruthenium(II) , 1980 .

[43]  T. Rauchfuss,et al.  Protonation‐Enhanced Lewis Acidity of Iridium Complexes Containing Noninnocent Amidophenolates , 2012 .

[44]  F. Hartl,et al.  Synthesis, Spectroscopy and Spectroelectrochemistry of Chlorocarbonyl {1,2-Bis[(2,6-diisopropylphenyl)imino]acenaphthene-κ2-N,N'}rhodium(I) , 2003 .

[45]  S. Ernst,et al.  ESR of homo- and heteroleptic mono- and dinuclear tris(.alpha.-diimine)ruthenium radical complexes , 1990 .

[46]  P. Maitlis,et al.  Pentamethylcyclopentadienyl-rhodium and -iridium complexes. Part 22. Blue five-co-ordinate rhodium(III) complexes derived from catechol and related compounds , 1979 .