Bromo‐ and Polybromoantimonates(V): Structural and Theoretical Studies of Hybrid Halogen‐Rich Halometalate Frameworks
作者:Sergey A. Adonin、Mikhail A. Bondarenko、Pavel A. Abramov、Alexander S. Novikov、Pavel E. Plyusnin、Maxim N. Sokolov、Vladimir P. Fedin
DOI:10.1002/chem.201801338
日期:2018.7.17
Cation‐dependent reactions “[SbBr6]3−+Br2+HBr+CationBrx” result in the formation of bromide/polybromide complexes with zero‐, one‐, two‐, or three‐dimensional supramolecular frameworks and different Br/Sb ratios (up to 11). Seven new compounds representing six structural types were characterized by XRD and thermogravimetric analysis and DFT calculations enabled estimation of the energies of the Br⋅⋅⋅Br
The deprotonation rate constants and kinetic isotope effects of the cation radicals have been determined by combined use of direct electrochemical techniques at micro- and ultramicroelectrodes, redox catalysis, and laser flash photolysis, over a extended series of opposing bases. Significant steric hindrance to deprotonation results from encumbering of the opposing base and of the functional carbon in the cation radical by alkyl groups. Kinetic isotope effects, ranging from 2 to 12 in terms of k(H)/k(D), appear upon substituting H to D at the functional carbon of the cation radical. The modest magnitude of the kinetic isotope effects and the fact that they are insensitive to steric hindrance show that proton (or H-atom) tunneling does not interfere significantly in the deprotonation reaction. All the cation radicals in the methylacridan series are strong acids, with pK(a)'s ranging from 0.8 to 1.7, as determined from thermodynamic cycles involving measured standard potentials and hydride-transfer equilibrium constants.