title: C-H activation of terminal alkynes by tris-(3,5-dimethylpyrazolyl)boraterhodiumneopentylisocyanide: new metal-carbon bond strengths.
abstract: C-H bond activation of terminal alkynes by [Tp'Rh(CNneopentyl)] (Tp' = hydridotris-(3,5-dimethylpyrazolyl)borate) resulted in the formation of terminal C-H bond activation products Tp'Rh(CNneopentyl)(C≡CR)H (R = t-Bu, SiMe(3), hexyl, CF(3), p-MeOC(6)H(4), Ph, and p-CF(3)C(6)H(4)). A combination of kinetic selectivity determined in competition reactions and activation energy for reductive elimination has allowed for the calculation of relative Rh-C(alkynyl) bond strengths. The bond strengths of Rh-C(alkynyl) products are noticeably higher than those of Rh-C(aryl) and Rh-C(alkyl) analogues. The relationship between M-C and C-H bond strengths showed a linear correlation (slope R(M-C/H-C) = 1.32), and follows energy correlations previously established for unsubstituted sp(2) and sp(3) C-H bonds in aliphatic and aromatic hydrocarbons.
authors.affiliation: Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Japan.
authors.forename: Gyeongshin
authors.initials: G
authors.lastname: Choi
authors.forename: James
authors.initials: J
authors.lastname: Morris
authors.forename: William W
authors.initials: WW
authors.lastname: Brennessel
authors.forename: William D
authors.initials: WD
authors.lastname: Jones