![]() ![]() In addition to the aforementioned monomeric zinc halides ZnX (X = Cl, Br, I), the dimeric bridging zinc fluoride ₂. ![]() Both of these exchange processes have been investigated with variable-temperature NMR spectroscopy in particular, the former exchange resolves at low temperatures and can be confirmed by exchange spectroscopy. Further mechanistic studies examine two noteworthy spectroscopic features of the system, namely rapid exchange (i) between the zinc and boryl formates ZnO₂CH and HCO₂Bpin, as well as (ii) between ZnH and ZnO₂CH. The Zn system has been investigated computationally, and the kinetics of insertion of CO₂ into the Zn-H bond of ZnH as well as the thermodynamics of the catalytic cycle have been examined. In all cases, hydroboration is more facile than the corresponding hydrosilylation. Similarly, ZnH serves as an effective catalyst for the hydrosilylation and hydroboration of a variety of ketones and aldehydes. In the absence of CO₂, ZnH also catalyzes the reduction of HCO₂Bpin to the methanol level, MeOBpin. This reactivity enables it to serve as a catalyst for the hydrofunctionalization of CO₂ specifically, ZnH catalyzes the hydrosilylation of CO₂ by (RO)₃SiH (R = Me, Et) at elevated temperatures to afford the respective silyl formates (RO)3SiO₂CH, as well as the hydroboration of CO₂ by HBpin at room temperature to afford the boryl formate HCO₂Bpin. ZnH also undergoes insertion of CO₂ into its Zn-H bond to afford the zinc formate, ZnO₂CH, in which the formate moiety exhibits a monodentate binding mode in the solid state. Both ZnN(SiMe₃)2 and ZnH provide access to a variety of monomeric derivatives, including the zinc halides ZnX (X = Cl, Br, I) and the zinc isocyanate ZnNCO the latter can be accessed directly via (i) metathesis of ZnH with Me₃SiNCO or (ii) a multistep reaction of ZnN(SiMe₃)₂ with CO₂. In Chapter 1, we describe the reaction of the protonated ligand H with the homoleptic zinc compounds Me₂Zn and Zn₂ to afford, respectively, ZnMe and ZnN(SiMe₃)₂ the latter has been used as a starting point for a wide range of reactivity.Most notably, the terminal zinc hydride, ZnH, can be accessed via either (i) metathesis of the zinc siloxide, ZnOSiPh₃, with either PhSiH₃ or HBpin, or (ii) direct metathesis of the zinc amide ZnN(SiMe₃)₂ with HBpin the latter reactivity is not precedented and offers a novel approach for the synthesis of molecular zinc hydrides. As such, numerous complexes of zinc have been synthesized and structurally characterized. The bis(2-pyridylthio)methyl ligand,, offers a synthetically convenient alternative to a variety of multidentate ligands, including most notably (tris(2-pyridylthio)methyl) and (bis(2-pyridylthio)(p-tolylthio)methyl), and, in contrast with, necessarily coordinates to metal centers in a κ³ fashion. 2022 Theses Doctoral Synthesis, Structures, and Reactivity of Zinc, Cadmium, and Magnesium Complexes Supported by Nitrogen Donor and Carboxylate Ligands ![]()
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