Tunable charge delocalization in dinickel quinonoid complexes.

When a 2,5-diamino-1,4-benzoquinonediimine C6H2(=NR)2(NHR)2 (2) is used as a bridging ligand, new dinickel(II) complexes [(acac)Ni[mu-C6H2(=NPh)4]Ni(acac)] (3a: R=Ph) and [(acac)Ni[mu-C6H2(=NCH2tBu)4]Ni(acac)] (3b: R=CH2tBu) are obtained; upon one-electron oxidation of these complexes delocalized mixed-valence compounds are formed. An X-ray diffraction study on 3b reveals equalization of the bond lengths within each of the ligand 6 systems and a lack of conjugation between them. The oxidized state in 3b+ involves both the bridging quinonoid ligand and the metal centers, with a major contribution coming from the bridging ligand. Electrochemical and spectroscopic methods were used to study the influence of the N-substituents of the tetranitrogen donor ligands 2. In this combined experimental and theoretical (DFT) study, it is also shown that the electronic structure within the dinickel system can be altered by addition of a coordinating ligand such as pyridine. The latter favors the high-spin configuration with semi-occupied metal-centered orbitals, leading to a metal-metal interaction in the mixed-valence Ni(II)-Ni(III) 3b+ system.

[1]  R. B. Sunoj,et al.  2,5-Dioxido-1,4-benzoquinonediimine (H2L2-), a hydrogen-bonding noninnocent bridging ligand related to aminated topaquinone: different oxidation state distributions in complexes [{(bpy)2Ru}2(mu-H2L)]n (n=0,+,2+,3+,4+) and [{(acac)2Ru}2(mu-H2L)]m (m=2-,-,0,+,2+). , 2005, Chemistry.

[2]  A. Das,et al.  Variable coordination mode of chloranilic acid. Synthesis, structure, and electrochemical properties of some osmium complexes. , 2005, Inorganic chemistry.

[3]  Evert Jan Baerends,et al.  Asymptotic correction of the exchange-correlation kernel of time-dependent density functional theory for long-range charge-transfer excitations. , 2004, The Journal of chemical physics.

[4]  C. Sangregorio,et al.  Thermally and light-induced valence tautomeric transition in a dinuclear cobalt-tetraoxolene complex. , 2004, Angewandte Chemie.

[5]  Laura Orian,et al.  Electronic communication in heterobinuclear organometallic complexes through unsaturated hydrocarbon bridges , 2004 .

[6]  M. Head‐Gordon,et al.  Failure of time-dependent density functional theory for long-range charge-transfer excited states: the zincbacteriochlorin-bacteriochlorin and bacteriochlorophyll-spheroidene complexes. , 2004, Journal of the American Chemical Society.

[7]  Tasuku Ito,et al.  Observation and dynamics of "charge-transfer isomers". , 2004, Angewandte Chemie.

[8]  T. Ziegler,et al.  A versatile direct approach to ortho-substituted azobenzenes from benzotriazoles. , 2004, Angewandte Chemie.

[9]  C. Kubiak,et al.  Structural, spectroscopic, and electrochemical studies of the complexes [Ni2(mu-CNR)(CNR)2(mu-dppm)2](n+) (n = 0, 1, 2): unusual examples of nickel(0)-nickel(I) and nickel(0)-nickel(II) mixed valency. , 2004, Inorganic Chemistry.

[10]  A. Albrecht-Gary,et al.  Acid-base sensors based on novel quinone-type dyes. , 2004, Chemistry.

[11]  Andrew P. Meacham,et al.  Mono- and dinuclear ruthenium carbonyl complexes with redox-active dioxolene ligands: electrochemical and spectroscopic studies and the properties of the mixed-valence complexes. , 2003, Inorganic chemistry.

[12]  D. Walther,et al.  Nickel(II) complexes of the type [RM(oxam)MR] (oxam: oxalamidinate, R= n -butyl, n -hexyl): the first binuclear n -alkyl nickel complexes , 2003 .

[13]  F. Neese,et al.  Mixed-Valent {FeIV(μ-O)(μ-carboxylato)2FeIII}3+ Core , 2003 .

[14]  R. Welter,et al.  Novel "Potentially antiaromatic", acidichromic quinonediimines with tunable delocalization of their 6 pi-electron subunits. , 2003, Journal of the American Chemical Society.

[15]  F. Cotton,et al.  A mixed-valence compound with one unpaired electron delocalized over four molybdenum atoms in a cyclic tetranuclear ion. , 2003, Chemical communications.

[16]  F. Tani,et al.  One-electron oxidized nickel(II)-(disalicylidene)diamine complex: temperature-dependent tautomerism between Ni(III)-phenolate and Ni(II)-phenoxyl radical states. , 2003, Journal of the American Chemical Society.

[17]  G. Jin,et al.  Novel, highly active binuclear 2,5-disubstituted Amino-p-benzoquinone-nickel(II) ethylene polymerization catalysts , 2003 .

[18]  E. McInnes,et al.  Ni(III) vs. Ni(II)-thiyl radical: charge-delocalisation in a binuclear Ni(III)Ni(II)-dithiolate complex. , 2003, Chemical communications.

[19]  Stefan Grimme,et al.  Substantial errors from time-dependent density functional theory for the calculation of excited states of large pi systems. , 2003, Chemphyschem : a European journal of chemical physics and physical chemistry.

[20]  W. Kaim.  The coordination chemistry of 1,2,4,5-tetrazines , 2002 .

[21]  Michael D. Ward,et al.  Non-innocent behaviour in mononuclear and polynuclear complexes: consequences for redox and electronic spectroscopic properties , 2002 .

[22]  Jean-Pierre Launay,et al.  Long-distance intervalence electron transfer , 2001 .

[23]  K. Wieghardt,et al.  Experimental evidence for the noninnocence of o-aminothiophenolates: coordination chemistry of o-iminothionebenzosemiquinonate(1-) pi-radicals with Ni(II), Pd(II), Pt(II). , 2001, Journal of the American Chemical Society.

[24]  T. Meyer,et al.  The localized-to-delocalized transition in mixed-valence chemistry. , 2001, Chemical reviews.

[25]  D. Walther,et al.  Di-, Tri-, and Tetranuclear Complexes of Ni, Pd, and Zn with Oxalamidinato Bridges: Syntheses, Structures and Catalytic Reactions , 2001 .

[26]  R. V. Eldik,et al.  Labilitätssteuerung in quadratisch‐planaren PtII‐Komplexen durch elektronische Kommunikation zwischen π‐Acceptorliganden , 2001 .

[27]  D. Jaganyi,et al.  Controlling the Lability of Square‐Planar PtII Complexes through Electronic Communication between π‐Acceptor Ligands , 2001 .

[28]  W. Kaim,et al.  Exploration of mixed-valence chemistry: inventing new analogues of the Creutz-Taube ion. , 2000, Accounts of chemical research.

[29]  G. Schuster,et al.  Long-range charge transfer in DNA: transient structural distortions control the distance dependence. , 2000, Accounts of chemical research.

[30]  Harriman,et al.  Controlling Electronic Communication in Ethynylated-Polypyridine Metal Complexes. , 2000, Angewandte Chemie.

[31]  Glöckle,et al.  An Exceedingly Stable Diiron(II,III) Complex Ion , 1999, Angewandte Chemie.

[32]  W. Kaim,et al.  Das außerordentlich stabile Dieisen(II,III)‐Komplexion [(tz){Fe(CN)5}2]5− mit Komproportionierungskonstanten zwischen 108 (in H2O) und 1019 (in CH3CN) , 1999 .

[33]  Katja Heinze,et al.  Elektronische Kommunikation in C4‐verbrückten zweikernigen Komplexen mit paramagnetischen Diphosphanmangan‐Endgruppen , 1999 .

[34]  H. Berke,et al.  Electronic Communication in C(4)-Bridged Binuclear Complexes with Paramagnetic Bisphosphane Manganese End Groups. , 1999, Angewandte Chemie.

[35]  A. Aukauloo,et al.  A Square-Planar Dinickel(II) Complex with a Noninnocent Dinucleating Oxamate Ligand: Evidence for a Ligand Radical Species , 1999 .

[36]  Frédéric Paul,et al.  Organometallic molecular wires and other nanoscale-sized devices: An approach using the organoiron (dppe)Cp*Fe building block , 1998 .

[37]  B. Kersting,et al.  First Examples of Dinickel Complexes Containing the N(3)Ni(&mgr;(2)-SR)(3)NiN(3) Core. Synthesis and Crystal Structures of [L(2)Ni(2)][BPh(4)](2) and [L(3)Ni(2)][BPh(4)](2) (L = 2,6-Di(aminomethyl)-4-tert-butyl-thiophenolate). , 1998, Inorganic chemistry.

[38]  L. Toupet,et al.  A Four-Oxidation-State Family of Coordinated Carbon: The First Isolable and Crystallographically Characterized Triradical [M]−C4−[M]3+ , 1998 .

[39]  J. Stubbe,et al.  Protein Radicals in Enzyme Catalysis. , 1998, Chemical reviews.

[40]  S. Subramanian,et al.  Synthesis, Spectroscopy, and Redox Behavior of the Binuclear Complex Cation [Ni2(6,6‘-spirobi(cyclam))]4+(cyclam = 1,4,8,11-Tetraazacyclotetradecane): Characteristics of a Transient Ni(II)−Ni(III) Species , 1997 .

[41]  J. Dawson,et al.  Heme-Containing Oxygenases. , 1996, Chemical reviews.

[42]  M. Ward.  A Dinuclear Ruthenium(II) Complex with the Dianion of 2,5-Dihydroxy-1,4-benzoquinone as Bridging Ligand. Redox, Spectroscopic, and Mixed-Valence Properties. , 1996, Inorganic chemistry.

[43]  M. Ward.  Metal-metal interactions in binuclear complexes exhibiting mixed valency; molecular wires and switches , 1995 .

[44]  C. Xu,et al.  Chemical oxidation of the ligand in nickel(II) cyclam : formation of a novel dinuclear complex and of a related cation containing a ligand radical ion , 1992 .

[45]  Evert Jan Baerends,et al.  Numerical integration for polyatomic systems , 1992 .

[46]  A. Bianchi,et al.  Synthesis, crystal structure, magnetic properties, and thermodynamic and electrochemical studies of the binuclear complex [(.mu.-oxalato)bis[(1,4,8,11-tetraazacyclotetradecane)nickel(II)] nitrate , 1988 .

[47]  H. Buergi,et al.  Mixed-valence ruthenium dimers. Molecular and electronic structure of the p-benzoquinone diimine bridged ion [(NH3)5Ru(bqd)Ru(NH3)5]5+ (bqd = p-benzoquinone diimine) and its relationship to the Creutz-Taube ion , 1985 .

[48]  E. Krausz,et al.  THE CREUTZ‐TAUBE COMPLEX REVISITED , 1984 .

[49]  D. Hendrickson,et al.  Magnetic exchange interactions in transition metal dimers. 11. Structural and magnetic characterization of [Ni2(tren)2(C6O4Cl2)](BPh4)2 and [Cu2(Me5dien)2(C6O4Cl2)](BPh4)2. Magnetic exchange interactions propagated by the dianions of 2,5-dihydroxy-1,4-benzoquinones , 1977 .

[50]  Evert Jan Baerends,et al.  Self-consistent molecular Hartree—Fock—Slater calculations I. The computational procedure , 1973 .

[51]  Henry Taube,et al.  Binuclear complexes of ruthenium ammines , 1973 .

[52]  Henry Taube,et al.  Direct approach to measuring the Franck-Condon barrier to electron transfer between metal ions , 1969 .

[53]  C. Kimich.  Einwirkung aromatischer Amine auf Nitrosophenol und Nitrosodimethylanilin , 1875 .

[54]  S. Kawata,et al.  Coordination compounds of 1,4-dihydroxybenzoquinone and its homologues. Structures and properties , 2002 .

[55]  Lucia Flamigni,et al.  Photoactive molecular wires based on metalcomplexes , 2000 .

[56]  P. Braunstein,et al.  First binuclear complex of an N,N′,N″,N‴-tetraalkyl 2,5-diamino-1,4-benzoquinonediimine , 2000 .

[57]  C. Ralston,et al.  Conversion of some substituted phenols to the corresponding masked thiophenols, synthesis of a dinickel(II) dithiolate macrocyclic complex and isolation of some metal- and ligand-based oxidation products , 2000 .

[58]  K. Inoue,et al.  Tacticity versus dimension of the extended structures in the crystals of heterospin magnets made of transition-metal complexes with the poly(aminoxyl) radical , 1998 .

[59]  Arthur J. Epstein,et al.  Tetracyanoethylene-based organic magnets , 1998 .

[60]  R. Blessing.  Data Reduction and Error Analysis for Accurate Single Crystal Diffraction Intensities , 1987 .

[61]  C. Jørgensen.  Oxidation Numbers and Oxidation States , 1969 .