Inorganometallic chemistry: Systems, properties and reactivity of mixed- and half-sandwich metallatricarbadecaboranyl complexes

The goal of the research presented in this dissertation was to explore the chemistry of metallatricarbadecaboranyl complexes, in particular comparing and contrasting reactivity with analogous cyclopentadienyl-metal complexes. The reaction of the tricarbadecaboranyl anion, 6-Ph-nido-5,6,9-C 3B7H9– with M(CO)5Br [M = Mn, Re] or [(η6-C10H8 )Mn(CO)3+]BF4– yielded the half-sandwich metallatricarbadecaboranyl analogues of (η 5-C5H5)M(CO)3 [M = Mn, Re]. The reaction of these complexes with isocyanide or phosphine reagents yielded a series of mono- and di-substituted metallatricarbadecaboranyl complexes. These reactions were found to involve a reversible η6-η4 cage slippage process that is analogous to the η5-η 3 ring-slippage that has been proposed to take place in related substitution reactions of cyclopentadienyl-metal complexes. Electrochemical studies of these complexes revealed that cage-slippage can be afforded through electrochemical reduction of the parent complexes and that the tricarbadecaboranyl group behaves like a noninnocent ligand. In addition, a general method for the selective functionalization of cyclopentadienyliron tricarbadecaboranyl complexes was developed based on selective halogenation of the tricarbadecaboranyl ligand followed by palladium-catalyzed Kumada, Sonogashira and Heck coupling reactions. Halogenation reactions yielded a series of B6 substituted 1-(η5-C5H5)-2-Ph-6-X- closo-1,2,3,4-FeC3B7H8 (X = Cl, Br, I) complexes, as well as 11 iodo and 6, 11 diiodated derivatives. Palladium-catalyzed coupling reactions of 1-(η5-C5H5)-2-Ph-6-I- closo-1,2,3,4-FeC3B7H8 with organomagnesium reagents, terminal acetylenes and olefins yielded a series of functionalized metallatricarbadecaboranyl complexes