Date of Award

Summer 2021

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Richard D. Adams

Abstract

Chapter 1 introduces two related topics with the primary focus on the background of zwitterions and the conceptual understanding of a metal-complexed zwitterion. It also discusses the potential of a metal-complexed zwitterion for a carbon-carbon bond formation reaction. Synthesis of the metal carbonyl cluster, Ru6(µ6-C)(µ-CO)(CO)16, is also discussed in detail. Then, the background with the importance of heterometallic cluster complexes is discussed with the help of various examples used for catalysis.

The reaction of hexaruthenium carbido carbonyl cluster, Ru6(µ6-C)(µ-CO)(CO)16, with C2H2 and Me3NO yielding first examples of two new zwitterionic complexes, Ru6C(CO)15(μ−η2−C2H2NMe3), 2.2, and Ru6C(CO)14(μ3−η4−C4H4NMe3), 2.3, are presented in Chapter 2. Addition of CO to 2.2 yields the complex Ru6C(CO)16(η1−E−C2H2NMe3), 2.4. that involves the transformation of a bridging-C2H2NMe3 ligand to a terminally coordinated position. On heating the complex 2.2, it undergoes thermal transformation to the complex Ru6C(CO)15(μ3−C2H2), 2.5 and similarly the complex 2.3 transforms to the complex Ru6C(CO)14(μ3−η4−C4H4), 2.6. Similarly, the reaction of Ru6(µ6-C)(µ-CO)(CO)16 with methyl propiolate and Me3NO yields the zwitterionic metal complex Ru6C(CO)16[η1−E−C(CO2Me)=C(H)NMe3], 2.7. The compound 2.7 thermally transforms to the complex Ru6C(CO)15[µ3−HC2(CO2Me)], 2.8. The structure, and transformations involved within the new complexes are described.

Reaction of Ru6(μ6-C)(CO)14(μ3−η4−C4H4), 3.2 with dimethyl acetylene dicarboxylate are presented in Chapter 3. Th namely, Ru6(μ6-C)(CO)16(μ−η4−C4H4), 3.3, Ru6(μ6-C)(CO)14[η6-C6H4(CO2Me)2], 3.4, Ru6(μ6-C)(CO)14(μ−η4−C4H4)[μ3−C2(CO2Me)2], 3.5, Ru6(μ6-C)(CO)14(μ−η4−C4H4)[μ3−C2(CO2Me)2], 3.6 and Ru6(μ6-C)(CO)14[μ3−η6−C6H4(CO2Me)2], 3.7. Compound 3.4 and 3.7 contains a metal-coordinated arene ring formed by cycloaddition reaction. Addition of dimethyl acetylene dicarboxylate to 3.3 yields the compound Ru6C(CO)15(μ−η4−C4H4)[μ−C2(CO2Me)2], 3.8. by replacing one of its bridging CO ligands with DMAD. On heating, compound 3.5 undergoes C-C coupling between the DMAD and the butadiendiyl ligand to give the complex Ru6C(CO)14[μ4−η6−CHCHCHCC(CO2Me)C(CO2Me)](μ−H), 3.9. Compound 3.3 was decarbonylated with Me3NO to compound Ru6C (CO)15(μ−η4−C4H4)(NMe3), 3.10. The reactions of the pentaruthenium nitride carbonyl cluster complex, [PPN][Ru5(µ5-N)(CO)14], 4.1, with the gold complex, Au(PPh3)]NO3, and copper complexes, [Cu(PPh3)Br]4, and [Cu(NCMe)4][BF4] are presented in Chapter 4. The reaction of [PPN][Ru5(µ5-N)(CO)14], 4.1, with Au(PPh3)]NO3 yielded three ruthenium-gold heterometallic nitrido carbonyl cluster complexes namely Ru4(µ4-N)(CO)12(µ-AuPPh3), 4.2, Ru5(µ5-N)(CO)14(µ-AuPPh3), 4.3 and Ru5(µ5-N)(CO)13(µ-AuPPh3)[µ3-(AuPPh3)2], 4.4. The reaction of [PPN][Ru5(µ5-N)(CO)14], 4.1, with [Cu(PPh3)Br] in presence of Tl[PF6] yielded three new ruthenium-copper heterometallic nitrido carbonyl cluster complexes namely Ru4(µ4-N)(CO)12[µ-Cu(PPh3)], 4.5, Ru5(µ5-N)(CO)13(PPh3)[µ3-Cu(PPh3)], 4.6, and Ru5(µ5-N)(CO)13[µ-Cu(PPh3)][(µ3-Cu(PPh3)]2, 4.7. The reaction of [PPN][Ru5(µ5-N)(CO)14], 4.1, with [Cu(NCMe)4][BF4] yield Ru5(µ5-N)(CO)14[µ3-Cu(NCMe)], 4.8. The synthesis and structures of new complexes are discussed herein.

The synthesis of the new dicopper cation of [{(IPr)Cu}2(µ-Cl)][PF6], 5.1 and its reaction with the complex [PPN][HOs3(CO)11], 5.2 are presented in Chapter 5. The reaction of 5.1 with the salt complex [PPN][HOs3(CO)11], 5.2 yielded the new osmium-copper heterometallic complex Os3(CO)11(H)[µ-Cu(IPr)], 5.3, the first example of Cu – Os carbonyl cluster complex containing a N-heterocyclic carbene ligand.

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© 2021, Nutan Damodhar Wakdikar

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