Ion Chemistry of Cyanides and Isocyanides. 1. The Carbon Lone Pair as Proton Acceptor: Proton Affinities of Isocyanides. Alkyl Cation Affinities of N, O, and C Lone-Pair Donors

摘要

The present paper consists of three parts. The first part presents the experimental results and a qualitative discussion of some aspects of the results and a qualitative discussion of some aspects of the results. The second part deals with alkyl ion affinities. For this purpose we note that protonated isocyanides may be considered alkylated hydrogen cyanides, i.e., HCN-R(+). We, therefore,use the present data to derive the alkyl cation affinities of HCN, i.e., the bond-dissociation energies D (R-NCH(+)). These results are compared with the alkyl cation affinities of other lone-pair donors, specifically, H2O), NH3, and HNC. The point of interest here is whether the alkyl cation affinities correlate with stabilities of the ions as measured by the hydride affinities of R+. The last part presents a theoretical examination of the trends observed in the experimental data. Specifically, we look into the following questions; (1) Why is the proton affinity of RNC higher than that of the corresponding RCN isomer and why are these differences independent of R. (2) What bond length changes occur in RNC upon protonation and what are the origins of these changes. (3) What is the source of the alkyl substituent effect on the observed proton affinities: Keywords: Protons; Affinities; Cyanides; Isocyanides; Alkyl compounds; Effects.