Browsing by Subject "Metal-metal bonding"

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    Synthesis, Characterization, and Reactivity of Early-Late Multimetallic Complexes Supported by Phosphinopyrrolides
    (2018-07) Dunn, Peter
    Interest in metal-metal bonding in polymetallic complexes has undergone a recent resurgence due to potential application towards small molecule transformations with green energy implications. In particular, complexes containing both a late transition metal and early transition metal have been the focus of extensive study, under the presumption that pairing highly differentiated metal centers may significantly alter the fundamental chemistry of the resulting molecules. To further understand and develop multimetallic chemistry, new ligand scaffolds are necessary to support multiple metal sites. This research focuses on the use of a new 2-diphenylphosphinopyrrolide ligand to synthesize group 4, 5, and 6 based metalloligands. Successful treatment with a late transition metal results in both bi- and trimetallic complexes. The fundamental structure, bonding, and reactivity of these complexes will be discussed as well as potential strategies for the synthesis of other polymetallic complexes.
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    Synthesis, characterization, and reactivity of metal-metal bonded complexes with cobalt, iron, and manganese
    (2014-11) Tereniak, Stephen J.
    Metal-metal bonding is important in dirhodium catalysts that mediate carbene insertions into C-H bonds, cyclopropanations, aziridinations, and ylide formations. Additionally, it has been suggested that certain intermediates in NiFe hydrogenases contain a nickel-iron bond. In light of the successful applications of dirhodium complexes in organic chemistry, as well as the role metal-metal bonds play in biology, the design of synthetic bimetallic complexes with mid-to-late first-row transition metals is of great interest. Yet, few examples of mid-to-late first-row transition metal complexes exhibiting metal-metal bonding have been reported, and even more strikingly, very few mid-to-late heterobimetallic complexes have been prepared. In the second chapter of this thesis, the synthesis and characterization of an isostructural series of dicobalt, cobalt-iron, cobalt-manganese, diiron, and iron-manganese complexes supported by a new binucleating ligand is disclosed. The diiron compound has a much shorter crystallographic metal-metal distance than the other four complexes. Experimental and theoretical work suggests that the short iron-iron distance is due to the full delocalization of the d orbitals, which leads to an S = 3 ground state. This is in contrast to the other four bimetallics, in which the magnetic interactions are modeled as high-spin metal centers that antiferromagnetically couple. In the third chapter, the synthesis and characterization of a dicobalt organometallic complex and a series of organometallic aluminum-cobalt complexes is described. Isostructural dicobalt benzyl and aluminum-cobalt benzyl compounds are compared using experiment and theory. A series of C-C bond forming experiments from the reaction of R-X compounds with the metal-cobalt benzyl complexes suggests that both the dicobalt compound and the aluminum-cobalt compound are capable of one-electron chemistry, whereas only the aluminum-cobalt complex undergoes two-electron reactions. These results are explained by the electronic structure of the two compounds: the aluminum-cobalt complex has the aluminum(III)cobalt(I) oxidation state, whereas calculations suggest that the dicobalt complex is cobalt(II)cobalt(II). In the fourth chapter, the synthesis and characterization of a series of hexairon and tetrairon clusters related by one-, two-, or three-electron redox steps is reported. In the fifth chapter, the role of some of these clusters in the dioxygen reactivity of a diiron(II) complex is revealed.