@article{THESIS,
      recid = {732},
      author = {Olechnowicz, Frank},
      title = {Synthesis and Reactivity of Low Coordinate Nickel Sulfide  Complexes},
      publisher = {University of Chicago},
      school = {Ph.D.},
      address = {2017-03},
      number = {THESIS},
      pages = {168},
      abstract = {This thesis describes the chemistry of Ni complexes  supported by an N-Heterocyclic Carbene (NHC) ligand that  contain sulfur atoms in different binding modes.  The  unique steric and electronic properties of NHCs allow for  the preparation and interconversion of four different  sulfur-based groups.  These complexes are markedly  different than related complexes in the literature, and can  be used as a model to study the H2 activation step of the  hydrodesulfurization process.
Chapter One describes the  prevalence of nickel complexes containing bridging thiolate  and sulfide groups.  These complexes serve key roles in the  small molecule activation and electron transport in enzyme  active sites, and perform the key activation step of H2 in  the hydrodesulfurization process.  Model used to study this  activation step exhibit fluxional behavior in solution,  which limits the conclusions about the exact mechanistic  details.  These limitations can be overcome by using an NHC  ligand.  The core imidazole ring imparts NHC ligands with  net electron donor ability that is greater than that of  phosphine ligands.  Additionally NHC ligands possess  lateral steric bulk that can shelter a metal center and  support low-coordinate environments.
Chapter Two describes  the synthesis and reactivity of the dinuclear bridging  disulfide complex {(IPr)ClNi}2(μ2 η2,η2-S2) (IPr =  1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) .  This  complex can be converted to a mononuclear  (IPr)(AdNC)Ni(η2-S2) complex with a terminal disulfide, a  dinuclear {(IPr)Ni(μ-S)}2 complex with two bridging  sulfides, and a dinuclear {(IPr)Ni(μ-SH)}2 complex two  bridging hydrosulfides.  Most interestingly, the bridging  sulfide and bridging hydrosulfide complexes are  interconverted through reaction with H2 and H atom  abstractor 2,4,6-tBu3-phenoxy radical.
In Chapter Three,  the hydrogenation of {(IPr)Ni(μ-S)}2 to {(IPr)Ni(μ-SH)}2 is  probed in depth through a combination of kinetic studies  and DFT calculations.  These results show that H2 adds  across a Ni-S bond in a heterolytic manner to generate a  Ni(H)(μ-S)(μ-SH)Ni intermediate that rearranges to the  product by H atom migration from Ni to the remaining μ-S  ligand.
Chapter Four describes the reaction of  {(IPr)Ni(μ-S)}2 with H-BPin to produce  {(IPr)Ni}2(μ-SH)(μ-SBPin).  This reaction suggests that  heterolytic E-H bond activation by the Ni2(μ-S)2 unit may  be a general reaction.},
      url = {http://knowledge.uchicago.edu/record/732},
      doi = {https://doi.org/10.6082/M1NC5Z8K},
}