A Reduced beta-Diketiminato-Ligated Ni3H4 Unit Catalyzing H/D Exchange

Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Strasse 2, 12489 Berlin, Germany.
Journal of the American Chemical Society (Impact Factor: 12.11). 10/2010; 132(39):13684-91. DOI: 10.1021/ja106266v
Source: PubMed


An investigation concerning the stepwise reduction of the β-diketiminato nickel(II) hydride dimer [LNi(μ-H)(2)NiL], 1 (L = [HC(CMeNC(6)H(3)(iPr)(2))(2)](-)), has been carried out. While the reaction with one equivalent of potassium graphite, KC(8), led to the mixed valent Ni(I)/Ni(II) complex K[LNi(μ-H)(2)NiL], 3, treatment of 1 with two equivalents of KC(8) surprisingly yielded in the trinuclear complex K(2)[LNi(μ-H)(2)Ni(μ-H)(2)NiL], 4, in good yields. The Ni(3)H(4) core contains one Ni(II) and two Ni(I) centers, which are antiferromagnetically coupled so that a singlet ground state results. 4 represents the first structurally characterized molecular compound with three nickel atoms bridged by hydride ligands, and it shows a very interesting chemical behavior: Single-electron oxidation yields in the Ni(II)(2)Ni(I) compound K[LNi(μ-H)(2)Ni(μ-H)(2)NiL], 5, and treatment with CO leads to the elimination of H(2) with formation of the carbonyl complex K(2)[LNi(CO)](2), 6. Beyond that, it could be shown that 4 undergoes H/D exchange with deuterated solvents and the deuteride-compound 4-D(4) reacts with H(2) to give back 4. The crystal structures of the novel compounds 3-6 have been determined, and their electronic structures have been investigated by EPR and NMR spectroscopy, magnetic measurements, and DFT calculations.

4 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: The catalytic system Ni(COD)2/BF3·OEt2 is highly active in the addition polymerization of nor-bornene (NB). Its activity, which is up to 1930 (kg NB) (mol Ni)−1 h−1, is higher than the activity of the other known nickel complex catalysts. Another advantage of this system over the latter is that it contains a smaller proportion of a Lewis acid (5 molar parts or below) and no conventional stabilizing organoelement ligands. The activity of this system in NB polymerization has been investigated by Fourier-transform IR spectroscopy. According to EPR data, NB polymerization is accompanied by the formation of low-spin complexes of trivalent nickel, which result from the oxidative addition of the monomer to univalent nickel complexes. A metallacyclic mechanism involving Ni(I) and Ni(III) complexes is suggested for NB polymerization.
    Kinetics and Catalysis 07/2012; 53(4). DOI:10.1134/S002315841204009X · 0.76 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The easily electronically and sterically tunable β-diketiminates are widely used auxiliary ligands for the creation of a wide range of metal complexes with various oxidation states in all groups of the periodic table. This review article highlights the recent advances of univalent β-diketiminatometal complexes. Such low-valent metals supported by β-diketiminates display remarkable metal–metal bonding, organic functionality and small molecule activations, reactivity relevant to biological active sites, and catalytic reactivity.
    Coordination Chemistry Reviews 03/2012; 256(s 5–8):722–758. DOI:10.1016/j.ccr.2011.12.012 · 12.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: It has been shown that the system Ni(COD)2/BF3∙OEt2 may polymerize norbornene with the activity of 1930kgNB/molNih. This catalytic system is characterized by minor content of the Lewis acid; the activity peaks at the molar ratio of B:Ni=5. The norbornene polymerization was first demonstrated to be attended with the formation of trivalent nickel metallocyclic complexes. A monovalent nickel complex was used as a precursor for the active species.
    Catalysis Communications 03/2011; 12(7):634-636. DOI:10.1016/j.catcom.2010.12.016 · 3.70 Impact Factor
Show more