Design, syntheses and characterizations of new functionalized tricarbadecaborane anion ligands and their transition metal coordination chemistry

The goal of the research presented in this dissertation was to design and synthesize new functionalized tricarbadecaborane anion ligands, explore their transition metal coordination chemistry and their similarities with π-coordinating ligands like the organic cyclopentadienyl ligand.; The systematic one carbon insertion reaction of different nitrile compounds with arachno-6,8-C₂B₇H₁₂ − yielded a series of monoanionic tricarbadecaborane ligands, (6-R-nido-5,6,9-C₃B₇H₉) −, [R = Ph, (CH₂)₄CN, BrC₆H ₄OSiMe₃CH, BH₃NMe₂(CH₂) ₂, and C₁₄H₁₁]. These ligands were successfully employed to produce a series of metallatricarbadecaboranyl analogs of ferrocene having the general formula 1-(η5-C₅H₅)-2-R- closo-1,2,3,4-FeC₃B₇H₉. The inability of the 6-Ph-nido-5,6,9-C₃B₇H₉ − ligand to form bis-cage complexes and the absence of cage-isomerization made it a more efficient and selective ligand than the previous 6-Me-nido-5,6,9-C₃B₇H ₉− anion, giving higher yields and single products in its reaction with transition metals.; The tricarbadecaboranyl anions, (6-R-nido-5,6,9-C ₃B₇H₉)−, [R = Ph, Me] have been employed to produce a series of metallatricarbadecaboranyl analogs of the group VIII metallocenes. Electrochemical studies revealed that RC ₃B₇H₉ analogs of Cp metal complexes were oxidatively more stable and underwent facile reduction reactions. Reaction of 1-(η 5-C₅H₅)-2-Ph-closo-1,2,3,4-FeC ₃B₇H₉ with Cr(CO)₆ resulted in the formation of the arene-substituted complex 1-(η5-C ₅H₅)-2-[(η6-C₆H₅)Cr(CO) ₃]-closo-1,2,3,4-FeC₃B₇H ₉. Complexes 1-(η5-C₁₀H₁₅)-2-Me- closo-1,2,3,4-RuC₃B₇H₉ and 1-(η5-C₅H₅)-2-Ph-closo -1,2,3,4-FeC₃B₇H₉ were found to undergo reversible cage-slippages between the η6–η 4 coordination modes during the association-dissociation reaction with t-BuNC to produce 8-(η5-C₅Me ₅)-8-(CNBut)-9-Me-nido-8,7,9,10-RuC ₃B₇H₉ and 8-(η5-C₅H ₅)-8-(CNBut)-9-Ph-nido-8,7,9,10-FeC ₃B₇H₉, respectively.; Preliminary studies on 1-(η5-C₅H₅ )-1-Br-2-Ph-closo-1,2,3,4-VC₃B₇H ₉ and commo-Nb-1-Cl-(4-Me-closo-1,2,3,4-NbC ₃B₇H₉)₂ revealed these compounds to be effective cytotoxic agents against murine and human leukemia and lymphoma growth as well as HeLa suspended uterine carcinoma.