Abstract
The accurate S-H bond dissociation enthalpies [BDE(S-H)] for a series of meta and para substituted thiophenols (X-C 6 H 4 -SH, X = H, F, Cl, CH 3 , OCH 3 , NH 2 , CF 3 , CN, and NO 2 ) have been estimated by using the (RO)B3LYP procedure with 6-311++G(2df,2p) basis set. The proton affinities [PA(S - )] at the sulfur site of the corresponding thiophenoxide ions (X-C 6 H 4 -S - ) and adiabatic electron affinities (EA a ) of thiophenoxy radicals have also been evaluated at the same level of calculations. The BDE(S-H) of the parent thiophenol has been evaluated to be 332.6 ′ 4.0 kJ/mol, which is in agreement rather with the earlier experimental value of 331.0 kJ/mol (Bordwell et al., J. Am. Chem. Soc. 1994, 116, 6605) than the more recent value of 349.4 kJ/mol (Santos et al., J. Phys. Chem. A 2002, 106, 9883). The effects of para and meta substituents on the BDE(S-H) and PA(S - ) have been critically analyzed considering the change in stabilities of the neutral molecule, radical and anions with the change in substituent, and its position. The correlations of Hammett's substituent constants with the BDE(S-H) and PA(S - ) values have also been explored.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.