@phdthesis{Zell2011,
  author    = {Zell, Thomas},
  title     = {NHC-stabilisierte Nickel-Komplexe in der st{\"o}chiometrischen und katalytischen Element-Element-Bindungsaktivierung},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-57484},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {Die vorliegende Arbeit befasst sich mit Untersuchungen von Element-Element- Bindungsaktivierungsreaktionen des dinuklearen Nickel(0)-NHC-Komplex [Ni2(iPr2Im)4(COD)] A mit verschiedenen reaktionstr{\"a}gen Substraten, die ihrerseits wichtige Ausgangsstoffe f{\"u}r katalytische Anwendungen sind. Die Arbeit gliedert sich dabei in vier verschiedene Teile.},
  subject      = {Heterocyclische Carbene <-N>},
  language  = {de}
}
@phdthesis{Tian2021,
  author    = {Tian, Yaming},
  title     = {Selective C-X and C-H Borylation by N-Heterocyclic Carbene Nickel(0) Complex},
  doi       = {10.25972/OPUS-21300},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213004},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Organoboron compounds are important building blocks in organic synthesis, materials science, and drug discovery. The development of practical and convenient ways to synthesize boronate esters attracted significant interest. Photoinduced borylations originated with stoichiometric reactions of arenes and alkanes with well-defined metal-boryl complexes. Now photoredox-initiated borylations, catalyzed either by transition-metal or organic photocatalysts, and photochemical borylations with high efficiency have become a burgeoning area of research. In this chapter, we summarize research in the field of photocatalytic C-X borylation, especially emphasizing recent developments and trends, based on transition-metal catalysis, metal-free organocatalysis and direct photochemical activation. We focus on reaction mechanisms involving single electron transfer (SET), triplet energy transfer (TET), and other radical processes. We developed a highly selective photocatalytic C-F borylation method that employs a rhodium biphenyl complex as a triplet sensitizer and the nickel catalyst [Ni(IMes)2] (IMes = 1,3-dimesitylimidazolin-2-ylidene) for the C-F bond activation and defluoroborylation process. This tandem catalyst system operates with visible (400 nm) light and achieves borylation of a wide range of fluoroarenes with B2pin2 at room temperature in excellent yields and with high selectivity. Direct irradiation of the intermediary C-F bond oxidative addition product trans-[NiF(ArF)(IMes)2] leads to fast decomposition when B2pin2 is present. This destructive pathway can be bypassed by indirect excitation of the triplet states of the nickel(II) complex via the photoexcited rhodium biphenyl complex. Mechanistic studies suggest that the exceptionally long-lived triplet excited state of the Rh biphenyl complex used as the photosensitizer allows for efficient triplet energy transfer to trans-[NiF(ArF)(IMes)2], which leads to dissociation of one of the NHC ligands. This contrasts with the majority of current photocatalytic transformations, which employ transition metals as excited state single electron transfer agents. We have previously reported that C(arene)-F bond activation with [Ni(IMes)2] is facile at room temperature, but that the transmetalation step with B2pin2 is associated with a high energy barrier. Thus, this triplet energy transfer ultimately leads to a greatly enhanced rate constant for the transmetalation step and thus for the whole borylation process. While addition of a fluoride source such as CsF enhances the yield, it is not absolutely required. We attribute this yield-enhancing effect to (i) formation of an anionic adduct of B2pin2, i.e. FB2pin2-, as an efficient, much more nucleophilic {Bpin-} transfer reagent for the borylation/transmetalation process, and/or (ii) trapping of the Lewis acidic side product FBpin by formation of [F2Bpin]- to avoid the formation of a significant amount of NHC-FBpin and consequently of decomposition of {Ni(NHC)2} species in the reaction mixture. We reported a highly selective and general photo-induced C-Cl borylation protocol that employs [Ni(IMes)2] (IMes = 1,3-dimesitylimidazoline-2-ylidene) for the radical borylation of chloroarenes. This photo-induced system operates with visible light (400 nm) and achieves borylation of a wide range of chloroarenes with B2pin2 at room temperature in excellent yields and with high selectivity, thereby demonstrating its broad utility and functional group tolerance. Mechanistic investigations suggest that the borylation reactions proceed via a radical process. EPR studies demonstrate that [Ni(IMes)2] undergoes very fast chlorine atom abstraction from aryl chlorides to give [NiI(IMes)2Cl] and aryl radicals. Control experiments indicate that light promotes the reaction of [NiI(IMes)2Cl] with aryl chlorides generating additional aryl radicals and [NiII(IMes)2Cl2]. The aryl radicals react with an anionic sp2-sp3 diborane [B2pin2(OMe)]- formed from B2pin2 and KOMe to yield the corresponding borylation product and the [Bpin(OMe)]•- radical anion, which reduces [NiII(IMes)2Cl2] under irradiation to regenerate [NiI(IMes)2Cl] and [Ni(IMes)2] for the next catalytic cycle. A highly efficient and general protocol for traceless, directed C3-selective C-H borylation of indoles with [Ni(IMes)2] as the catalyst was achieved. Activation and borylation of N-H bonds by [Ni(IMes)2] is essential to install a Bpin moiety at the N-position as a traceless directing group, which enables the C3-selective borylation of C-H bonds. The N-Bpin group which is formed is easily converted in situ back to an N-H group by the oxidiative addition product of [Ni(IMes)2] and in situ-generated HBpin. The catalytic reactions are operationally simple, allowing borylation of of a variety of substituted indoles with B2pin2 in excellent yields and with high selectivity. The C-H borylation can be followed by Suzuki-Miyaura cross-coupling of the C-borylated indoles in an overall two-step, one-pot process providing an efficient method for synthesizing C3-functionalized heteroarenes.},
  subject      = {Borylierung},
  language  = {en}
}
@phdthesis{Schmidt2013,
  author    = {Schmidt, David},
  title     = {N-Heterocyclische Carbene und NHC stabilisierte Nickelkomplexe in der Aktivierung von Element-Element- und Element-Wasserstoff-Bindungen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-90141},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {Die vorliegende Arbeit befasst sich sowohl mit der st{\"o}chiometrischen als auch mit der katalytischen Aktivierung von Element-Element-Bindungen an NHC-stabilisierten Nickel(0) Komplexen.},
  subject      = {Nickelkomplexe},
  language  = {de}
}
@phdthesis{Paul2018,
  author    = {Paul, Ursula Sofia D{\´e}sir{\´e}e},
  title     = {Studies on the Reactivity of Iridium Bis(phosphinite) Pincer Complexes towards Phosphines, Boranes and their Lewis Adducts and on the Reactivity of Cyclic (Alkyl)(Amino) Carbenes and Nickel Complexes thereof},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-151963},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {The first part of the present work provides an insight into the chemistry of iridium complexes bearing the bis(phosphinite) pincer ligand tBuPOCOP (k3-C6H3-1,3-(OPtBu2)2) towards primary boranes and phosphines as well as phosphine-borane Lewis adducts. It furthermore encloses some more detailed studies on their application as catalyst for the dehydrogenative coupling of the latter compounds. The results presented herein can be divided into three sections: I. synthesis and characterization of aryl dihydroborate ligated iridium(III) complexes II. and aryl phosphine coordinated iridium(I) and dihydrido iridium(III) complexes, III. as well as studies on the reactivity of the parent iridium pincer complexes towards BH3 adducts of primary phosphines, which led to first results in the homogeneous catalytic dehydrocoupling of P-aryl substituted phosphine boranes mediated by such iridium pincer complexes. The second part of the present work provides an insight into the chemistry of cyclic (alkyl)(amino) carbene-stabilized nickel complexes as well as it encloses some more detailed studies on the properties and reactivity of the free carbenes itself. The results presented herein can be divided into four sections: I. synthesis and characterization of cyclic (alkyl)(amino) carbene-stabilized nickel carbonyl complexes, II. which allow the evaluation and quantification of the steric and electronic properties of these cyclic (alkyl)(amino) carbenes, III. first studies on the reactivity of these novel nickel complexes, and IV. investigations on C-F and C-H bond activation at the carbene center of cyclic (alkyl)(amino) carbenes.},
  subject      = {Iridiumkomplexe},
  language  = {en}
}
@phdthesis{Fischer2012,
  author    = {Fischer, Peter},
  title     = {Synthese NHC-stabilisierter Nickel-Komplexe und deren Einsatz in der Kohlenstoff-Fluor-Bindungsaktivierung},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-71511},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {Die vorliegende Arbeit befasst sich zum einen mit der Synthese und Reaktivit{\"a}t des zweiwertigen Nickel-Biscarben-Komplexes trans-[Ni(iPr2Im)2Br2], zum anderen mit der Aktivierung von C-F-Bindungen fluorierter Aromaten und dem Einsatz von [Ni2(iPr2Im)4(COD)] in der st{\"o}chiometrischen und katalytischen Hydrodefluorierung.},
  subject      = {Heterocyclische Carbene <-N>},
  language  = {de}
}
@phdthesis{Berthel2019,
  author    = {Berthel, Johannes H. J.},
  title     = {Synthese und Charakterisierung neuer NHC-stabilisierter Nickelkomplexe f{\"u}r die Gasphasenabscheidung},
  doi       = {10.25972/OPUS-14757},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-147571},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Die vorliegende Arbeit befasst sich mit der Synthese und Charakterisierung NHC-stabilisierter Nickelkomplexe, die durch weitere Co-Liganden wie Carbonyle, Olefine, Alkine, Alkyle, Cyanide oder Allylliganden koordiniert sind. Ferner gibt diese Arbeit einen {\"U}berblick {\"u}ber die thermischen Eigenschaften dieser Verbindungen, um deren Potenzial f{\"u}r den Einsatz zur Abscheidung elementaren Nickels in CVD- bzw. ALD-Prozessen absch{\"a}tzen zu k{\"o}nnen. Dabei konnten vor allem die Substanzklassen der Carbonyl- und Alkylkomplexe als geeignete Pr{\"a}kursoren f{\"u}r die Gasphasenabscheidung elementaren Nickels identifiziert werden, von denen einige ausgew{\"a}hlte Vertreter bereits erfolgreich in CVD-Prozessen getestet wurden.},
  subject      = {Nickelkomplexe},
  language  = {de}
}