Date of Award
2018
Document Type
Open Access Dissertation
Department
Chemistry and Biochemistry
First Advisor
Richard D. Adams
Abstract
The background and importance of aromatic C-H bond activation by metal complexes are discussed in Chapter 1 with the help of various examples from the literature. Synthesis of the dirhenium complex Re2(CO)8(-C6H5)(-H) 1.1 is also discussed in detail. It also includes work done on C-H activation on arenes and heteroarenes by previous members of Dr. Adams’ group. The reactions of Re2(CO)8(-C6H5)(-H) with naphthalene and anthracene yielding the first multiply-CH activated arene products by the multiple oxidative-addition processes are presented in Chapter 2. The reaction of Re2(CO)8(-C6H5)(-H) with itself yielded the doubly-Re2-metalated C6H4 bridged compound Re2(CO)8(µ-H)(µ-1,µ-3- C6H4)Re2(CO)8(µ-H), 2.3. The reaction of Re2(CO)8(-C6H5)(-H) with the nonplanar molecule, corannulene, resulting in formation of Re2(CO)8(µ-H)(µ-η2-1,2-C20H9), 3.2 is reported in Chapter 3. Three new isomeric doubly-metalated corannulene products: Re2(CO)8(µ-H)(µ-η2-1,2-µ- η2-10,11-C20H8)Re2(CO)8(µ-H), 3.3, Re2(CO)8(µ-H)(µ-η2-2,1-µ-η2-10,11- C20H8)Re2(CO)8(µ-H), 3.4 and Re2(CO)8(µ-H)(µ-η2-1,2-µ-η2-11,10-C20H8)Re2(CO)8(µ- H), 3.5 were formed when compound 3.2 was allowed to react with a second equivalent of Re2(CO)8(-C6H5)(-H). The products formed from the reactions of Re2(CO)8(μ-C6H5)(μ-H) with furan and 2,5-dimethylfuran are presented in Chapter 4. Two new isomeric dirhenium compounds vii Re2(CO)8(µ-η2-2,3-C4H3O)(µ-H), 4.1 and Re2(CO)8(µ-η2-3,2-C4H3O)(µ-H), 4.2, both of which contain a bridging σ-π coordinated furyl ligand were formed by the activation of CH bonds at the α and β position of furan, respectively. Studies of C-H activations of thiophene on reaction with Re2(CO)8(-C6H5)(-H) are reported in Chapter 5. Also, the dynamic activity of Re2(CO)8(-2-SC4H3)(-H), 5.2 on the NMR timescale involving rearrangements of the bridging thienyl ligand and ring opening of thiophene molecule by C-S bond cleavage is discussed in detail. The activation of formyl C-H bond of N,N-dimethylformamide (DMF) by Re2(CO)8[μ-η2-C(H)=C(H)Bun](μ-H), 6.1 is reported in chapter 6. This reaction yielded three products, Re2(CO)8(µ-2-O=CNMe2)(µ-H), 6.2, Re2(CO)7(NHMe2)(µ-2- O=CNMe2)(µ-H), 6.3 and Re2(CO)9(NHMe2), 6.4. Compounds 6.2 and 6.3 contain a C,O- 2-bridging dimethylformamido (O=CNMe2) ligand and a bridging hydrido ligand formed by the elimination of hexene from 6.1 and the oxidative addition of the formyl C-H bond of the DMF to the dirhenium group of 6.1. Compound 6.3 contains an NHMe2 ligand formed by the decarbonylation of DMF and the transfer of the formyl hydrogen atom to the NMe2 residue. Compound 6.4 contains a similarly formed NHMe2 ligand. The investigations of synthesis and reactivity of electronically unsaturated dirhenium compounds containing bridging gold-carbene groups are described in chapter 7. Re2(CO)8[μ-Au(NHC)](μ-Ph), 7.1 and Re2(CO)8[μ-Au(NHC)]2, 7.2, were obtained from the reaction of Re2(CO)8[μ-η2-C(H)=C(H)Bun](μ-H) with MeAu(NHC), NHC = 1,3- bis(2,6-diisopropylphenyl)imidazol-2-ylidene. Conversion of compound 7.1 to the new compound Re2(CO)8[μ-Au(NHC)](μ-H), 7.3 upon reaction with hydrogen is also discussed. Addition of CO to 3 yielded the new compound Re2(CO)9[Au(NHC)](μ-H), 7.4. viii Compound 7.3 also reacts with C2H2 by an addition with insertion into the Re – H bonds to yield the compound Re2(CO)8[μ-Au(NHC)](μ-C2H3), 7.5 which contains a - coordinated, bridging C2H3 ligand
Rights
© 2018, Poonam Dhull
Recommended Citation
Dhull, P.(2018). Multiple C-H Bond Activations Of Aromatic Compounds By Unsaturated Dirhenium Carbonyl Complexes. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/5010