Hydroxylation of N-heterocycle ligands observed in two unusual mixed-valence Cu(I)/Cu(II) complexes.

The chelate ligands 2,2 -bipyridine (bpy), 1,10-phenanthroline (phen), and their substituted derivatives have played an important role in the development of coordination chemistry,[1, 2] and over the decades a number of so-called anomalies have been reported in reactions of their metal complexes. To rationalize the anomalous properties of complexes such as [M(bpy)3] and [M(phen)3] , Gillard borrowed the idea of TMcovalent hydrates∫ from the organic literature and proposed an interesting mechanism,[3] the core of which is nucleophilic attack of a hydroxide ion on a coordinated heterocyclic ligand to form a covalent hydrate (CH); this may react further by intramolecular shift of OH or H2O onto the metal before the formation of the final products (Scheme 1). The mechanism

[1]  A. Katz,et al.  Bipyridine: the most widely used ligand. A review of molecules comprising at least two 2,2'-bipyridine units. , 2000, Chemical reviews.

[2]  Ian D. Williams,et al.  Solvothermal Synthesis of a Stable Coordination Polymer with Copper-I−Copper-II Dimer Units: [Cu4{1,4-C6H4(COO)2}3(4,4‘-bipy)2]n , 2000 .

[3]  J. McGarvey,et al.  Raman Spectroscopy of Three Average-Valence Dicopper Cryptates: Evidence for Copper-Copper Bonding. , 1998, Inorganic chemistry.

[4]  S. Lippard,et al.  Synthesis and Characterization of Spin-Delocalized Carboxylate-Bridged Cu(I)−Cu(II) Mixed-Valence Complexes Having Only Oxygen Donor Ligands , 1998 .

[5]  S. Ferguson-Miller,et al.  Heme/Copper Terminal Oxidases. , 1996, Chemical reviews.

[6]  Frank Neese,et al.  The Purple Mixed-Valence CuA Center in Nitrous-oxide Reductase: EPR of the Copper-63-, Copper-65-, and Both Copper-65- and [15N]Histidine-Enriched Enzyme and a Molecular Orbital Interpretation , 1996 .

[7]  T. Tomizaki,et al.  The Whole Structure of the 13-Subunit Oxidized Cytochrome c Oxidase at 2.8 Å , 1996, Science.

[8]  William B. Tolman,et al.  A thiolate-bridged, fully delocalized mixed-valence dicopper(I,II) complex that models the CuA biological electron-transfer site , 1996 .

[9]  Hartmut Michel,et al.  Structure at 2.8 Å resolution of cytochrome c oxidase from Paracoccus denitrificans , 1995, Nature.

[10]  V. McKee,et al.  Highly delocalized Cu(I)/Cu(II); a copper-copper bond? , 1991 .

[11]  M. Maestri,et al.  Covalent hydration and pseudobase formation in transition metal polypyridyl complexes: Reality or myth? , 1983 .

[12]  O. Farver,et al.  A nuclear magnetic resonance study of the bis(2,2'-bipyridine)platinum(II) cation in basic solution , 1979 .

[13]  M. Hoffman,et al.  Photophysics and photochemistry of aromatic nitrogen heterocycles. Fluorescence from 2,2'-bipyridine and 1,10-phenanthroline , 1979 .

[14]  V. Balzani,et al.  Photochemical and photophysical behavior of trans-diisothiocyanatobis(ethylenediamine)chromium(III) , 1978 .

[15]  M. Hoffman,et al.  Fluorescence from 2,2'-bipyridine. Evidence for covalent hydrate formation , 1977 .

[16]  R. Gillard.  Equilibria in complexes of n-heterocyclic molecules. part III [1, 2]. an explanation for classical anomalies among complexes of 1,10-phenanthrolines and 2,2́-bi- pyridyls , 1975 .

[17]  Jim A. Thomas,et al.  Stereoisomerically controlled inorganic architectures: synthesis of enantio- and diastereo-merically pure ruthenium–palladium molecular rods from enantiopure building blocks , 1996 .

[18]  R. Gillard,et al.  Isotope effects in complexed 2,2′-bipyridyl , 1996 .

[19]  W. Antholine,et al.  Crystallographic, spectroscopic and theoretical studies of an electron-deiocalized Cu(1.5)–Cu(1.5) complex , 1993 .

[20]  E. Constable.  The reactions of nucleophiles with complexes of chelating heterocyclic imines : a critical survey , 1983 .

[21]  N. Serpone,et al.  Interligand pockets in polypyridyl complexes. The crystal and molecular structure of the Cr(2,2′,2″-terpyridine)23+ ion , 1979 .