Small Molecule Activation by Dirhenium Carbonyl Complexes

Author

Meenal Kaushal

Date of Award

Summer 2022

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Richard D. Adams

Abstract

The background of small molecule activation is discussed in Chapter 1. Carbon-hydrogen (C-H) bond activation and carbon-carbon (C-C) bond formation using transition metal complexes are explained using examples from the literature. It also includes the previous work done by Dr. Adams’ lab on C-H bond activation and zwitterions in metal carbonyl complexes.

The reaction of Re₂(CO)₈(µ-C₆H₅)(µ-H) with vinyl acetate yielding three new products has been discussed in Chapter 2. One of the products Re₃(CO)₁₃(µ-η² -C₂H₃), 2.3 further reacts with I₂ resulting in the cleavage of Re(CO)₅ group to yield the known compound Re(CO)₅I and the new dirhenium complex Re₂(CO)₈I(µ-η² -C₂H₃), 2.6 containing a µ-η² -(σ+π) coordinated vinyl group.

The reaction of Re₂(CO)₁₀ with acetylene and Me₃NO, yielding dirhenium complex Re₂(CO)₉(NMe₃), 3.6 and the new zwitterionic complex Re₂(CO)₉[η ¹ -Ε-2- CH=CH(NMe₃)], 3.7 has been presented in chapter 3. Reactions of 3.7 with PMePh₂ and PPh₃ has yielded the zwitterionic 2-arylphosphonioethenyl-coordinated dirhenium carbonyl complexes, Re2(CO)9[η 1 -E-2-CH=CH(PPh2Me)], 3.9a and Re2(CO)9[η 1 -E-2- CH=CH(PPh3)], 3.9b and the zwitterionic 1-phosphonioethenyl ligand in the dirhenium carbonyl complexes, Re2(CO)9[η 1 -1-C(PPh2Me)(=CH2)], 3.10a, Re₂(CO)8[µ- η 2 -1- C(PPh₂Me)(=CH2)], 3.11a and Re₂(CO)8[[µ- η 2 -1-C(PPh₃)(CH₂)], 3.11b, respectively. Compound 3.10a was converted to 3.11a and the new compound Re₂(CO)7(µ-H)[ µ-η2 -1- (CH₂C)P(Ph)(Me)(o-C₆H₄)], 3.12 by decarbonylations using Me3NO.

Chapter 4 explains the reactions of the zwitterionic dirhenium complex Re₂(CO)₈[µ- η 2 -1-C(CH2)(PMePh₂)], 4.3 with the terminal alkynes, HC≡COEt and HC≡CPh. They yielded two new isomeric ethoxy-substituted dirhenium complexes, Re₂(CO)₇[µ- η ³ -C(H)C(OCH₂CH₃)CH₂C(PMePh₂)], 4.5 and Re₂(CO)7[µ- η ³ - C(OCH₂CH₃)C(H)CH₂C(PMePh₂)], 4.6 and one phenyl-substituted dirhenium complex Re2(CO)7[µ- η 3 -C(H)CPhCH2C(PMePh2)], 4.7, respectively, with each containing a bridging, substituted 1-phosphonio-3,4-butenyl ligand formed by loss of CO and the addition and coupling of one alkyne to the CH2 group of the 1-phosphonioethenyl ligand in 4.3. On heating, compound 4.5 was converted to two new compounds: Re₂(CO)₆(µ-H)[ µ- η ⁴ -C(H)C(OCH₂CH₃)CHC(PMePh₂)], 4.8, by loss of a CO ligand and a CH activation at the CH2 group in its C(H)C(OCH₂CH₃)CH2C(+PMePh₂) ligand and an isomer Re₂(CO)₆(PMePh₂)[ µ- η ⁴ -C(H)C(OCH₂CH₃)CHCH], 4.9.

Rights

© 2022, Meenal Kaushal

Recommended Citation

Kaushal, M.(2022). Small Molecule Activation by Dirhenium Carbonyl Complexes. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/6962