(Mu-eta2:eta2-disulfido)dinickel(II) complexes supported by 6-methyl-TPA ligands.

A series of (mu-eta(2):eta(2)-disulfido)dinickel(II) complexes 2(n) have been synthesized by the reaction of Na(2)S(2) and nickel(II) complexes 1(n) supported by tris[(pyridin-2-yl)methyl]amine (TPA; 1(0)) [(6-methylpyridin-2-yl)methyl]bis[(pyridin-2-yl)methyl]amine (Me(1)TPA; 1(1)), bis[(6-methylpyridin-2-yl)methyl][(pyridin-2-yl)methyl]amine (Me(2)TPA; 1(2)) and tris[(6-methylpyridin-2-yl)methyl]amine (Me(3)TPA; 1(3)), respectively, and characterised by UV-vis and resonance Raman spectroscopy. X-ray crystallographic analyses on 2(2) and 2(3) supported by Me(2)TPA and Me(3)TPA, respectively, have revealed that the Ni(2)S(2) core is largely bent (approximately 30 degrees) along the S-S axis, being in sharp contrast to the planar Ni(2)S(2) core structure of the (mu-eta(2):eta(2)-disulfido)dinickel(II) complexes reported so far. The UV-vis spectra of 2(0) and 2(1) supported by TPA and Me(1)TPA, respectively, exhibiting an intense absorption band at approximately 360 nm together with a shoulder around 400 nm and a weak and broad absorption band around 450-600 nm, are very close to those of 2(2) and 2(3), suggesting that 2(0) and 2(1) also exhibit a similar distorted Ni(2)S(2) core structure. Resonance Raman spectra of 2(n) showed a characteristic S-S stretching vibration mode at approximately 450 cm(-1) with an isotope shift Delta nu((32)S-(34)S) = 10-15 cm(-1). The reaction of 2(n) with (p-Me-C(6)H(4))(3)P gave (p-Me-C(6)H(4))(3)P=S quantitatively based on 2(n). Hammett analysis on the sulfur atom transfer process from 2(n) to the phosphine derivatives [(p-X-C(6)H(4))P; X = OMe, Me, H and Cl] has indicated that the reaction involves an electrophilic ionic mechanism. Moreover, the order of reactivity of 2(n) toward PPh(3) has been found as 2(0) > 2(3) > 2(1) > 2(2). On the basis of these results, the ligand effects of Me(n)TPA on the structure and reactivity of the nickel(II) complexes have been discussed.

[1]  T. Brunold,et al.  Synthesis and spectroscopic identification of a mu-1,2-disulfidodinickel complex. , 2009, Journal of the American Chemical Society.

[2]  S. Hikichi,et al.  Structural characterization and oxidation activity of a nickel(II) alkylperoxo complex. , 2009, Angewandte Chemie.

[3]  T. Brunold,et al.  New synthetic routes to a disulfidodinickel(II) complex: characterization and reactivity of a Ni2(mu-eta2:eta2-S2) core. , 2008, Inorganic Chemistry.

[4]  K. Karlin,et al.  Copper dioxygen adducts: formation of bis(mu-oxo)dicopper(III) versus (mu-1,2)Peroxodicopper(II) complexes with small changes in one pyridyl-ligand substituent. , 2008, Inorganic chemistry.

[5]  I. Willner,et al.  Cover Picture: Increasing the Complexity of Periodic Protein Nanostructures by the Rolling‐Circle‐Amplified Synthesis of Aptamers (Angew. Chem. Int. Ed. 1/2008) , 2008 .

[6]  K. Karlin,et al.  Copper(I)/S(8) reversible reactions leading to an end-on bound dicopper(II) disulfide complex: nucleophilic reactivity and analogies to copper-dioxygen chemistry. , 2007, Journal of the American Chemical Society.

[7]  Masatatsu Suzuki.  Ligand effects on dioxygen activation by copper and nickel complexes: reactivity and intermediates. , 2007, Accounts of chemical research.

[8]  K. Karlin,et al.  Aryl hydroxylation from a mononuclear copper-hydroperoxo species. , 2007, Journal of the American Chemical Society.

[9]  K. Karlin,et al.  Copper(II)-hydroperoxo complex induced oxidative N-dealkylation chemistry. , 2007, Journal of the American Chemical Society.

[10]  W. Tolman,et al.  Ligand structural effects on Cu2S2 bonding and reactivity in side-on disulfido-bridged dicopper complexes. , 2007, Inorganic chemistry.

[11]  T. Brunold,et al.  Identification of an "end-on" nickel-superoxo adduct, [Ni(tmc)(O2)]+. , 2006, Journal of the American Chemical Society.

[12]  W. Tolman,et al.  Characterization of a Complex Comprising a {Cu2(S2)2}2+ Core: Bis(μ‐S22−)dicopper(III) or Bis(μ‐S2.−)dicopper(II)? , 2005 .

[13]  R. Schenker,et al.  Spectroscopic and computational studies on the trans-mu-1,2-peroxo-bridged dinickel(II) species [{Ni(tmc)}2 (O2)](OTf)2: nature of end-on peroxo-nickel(II) bonding and comparison with peroxo-copper(II) bonding. , 2005, Inorganic chemistry.

[14]  R. Schenker,et al.  Spectroscopic elucidation of a peroxo Ni2(mu-O2) intermediate derived from a nickel(I) complex and dioxygen. , 2004, Angewandte Chemie.

[15]  R. Schenker,et al.  A monomeric nickel-dioxygen adduct derived from a nickel(I) complex and O2. , 2004, Inorganic chemistry.

[16]  T. Rauchfuss.  Research on soluble metal sulfides: from polysulfido complexes to functional models for the hydrogenases. , 2004, Inorganic chemistry.

[17]  Y. Makita,et al.  Aromatic hydrocarbon-catalyzed direct reaction of sulfur and sodium in a heterogeneous system: selective and facile synthesis of sodium monosulfide and disulfide. , 2003, Inorganic chemistry.

[18]  R. Schenker,et al.  Spectroscopic and computational studies on [(PhTt(tBu))2Ni2(mu-O)2]: nature of the bis-mu-oxo (Ni3+)2 diamond core. , 2002, Journal of the American Chemical Society.

[19]  T. Takata,et al.  Direct Preparation of Anhydrous Sodium Oligosulfides from Metal Sodium and Elemental Sulfur in Aprotic Organic Media Directed toward Synthesis of Silane Coupling Agent , 2002 .

[20]  W. Jones,et al.  Structure of [Ni(dippe)(μ-S)]2 and its reaction products. The nucleophilicity of the Ni2S2 fragment , 2002 .

[21]  K. Karlin,et al.  Formation, characterization, and reactivity of bis(mu-oxo)dinickel(III) complexes supported by a series of bis[2-(2-pyridyl)ethyl]amine ligands. , 2001, Journal of the American Chemical Society.

[22]  T. Brunold,et al.  Dioxygen activation by a nickel thioether complex: characterization of a Ni(III)(2)(mu-O)(2) core. , 2001, Journal of the American Chemical Society.

[23]  H. Hayashi,et al.  Synthesis, Structures, and Properties of Bis(μ-oxo)nickel(III) and Bis(μ-superoxo)nickel(II) Complexes: An Unusual Conversion of a NiIII2(μ-O)2 Core into a NiII2(μ-OO)2 Core by H2O2 and Oxygenation of Ligand , 2000 .

[24]  S. Fukuzumi,et al.  Aliphatic Hydroxylation by a Bis(μ-oxo)dinickel(III) Complex , 1999 .

[25]  W. Jones,et al.  Modeling the Hydrodesulfurization Reaction at Nickel. Unusual Reactivity of Dibenzothiophenes Relative to Thiophene and Benzothiophene , 1999 .

[26]  K. Sakai,et al.  Transesterification by (Hydroxo)nickel(II) Complex in the Presence of External Alcohol , 1999 .

[27]  W. Saak,et al.  Preparation of the first sulfur-containing cobalt and nickel complexes stabilised by the macrocyclic cyclam ligand; observation of S–H bond activation , 1999 .

[28]  S. Hikichi,et al.  First Synthesis and Structural Characterization of Dinuclear M(III) Bis(μ-oxo) Complexes of Nickel and Cobalt with Hydrotris(pyrazolyl)borate Ligand† , 1998 .

[29]  Masatatsu Suzuki,et al.  Structural and Electrochemical Comparison of Copper(II) Complexes with Tripodal Ligands. , 1996, Inorganic chemistry.

[30]  K. Karlin,et al.  Reversible reaction of O2 (and CO) with a copper(I) complex. X-ray structures of relevant mononuclear Cu(I) precursor adducts and the trans-(μ-1,2-peroxo)dicopper(II) product , 1993 .

[31]  B. Krebs,et al.  Nickel Complexes Containing Sterically Demanding Thiolate Ligands: [Ni8S(SC4H9)9]⊖, a Mixed-Valence Nickel Sulfide Thiolate Cluster, and [Ni4(SC3H7)8], a Homoleptic Nickel Thiolate† , 1989 .

[32]  W. Tremel,et al.  Synthesis and molecular structure of [Ni4(S2)(SCH2CH2S)4]2−, a mixed nickel-disulfide-thiolate anion with a prismatic Ni4S2 core , 1988 .

[33]  C. Mealli,et al.  An unusual disulfur-bridged nickel dimer with a Ni2S2 planar framework: an example of binuclear coupling promoted by transition metals , 1983 .

[34]  C. Mealli,et al.  Transition-metal complexes with sulfur atom as ligand. 2. Synthesis, properties, and structural characterization of thio, mercapto, and methylthio complexes of cobalt(I) and nickel(I) and -(II) with poly(tertiary phosphines) , 1978 .

[35]  J. Rolfe.  Emission Spectra of S2−, Se2−, and SeS− Ions in KI Crystals , 1968 .