Stereochemical study of the sterically crowded phenylselanylalkenes by means of ⁷⁷Se¹H spin–spin coupling constants

Abstract

Stereochemical study of five sterically crowded phenylselanylalkenes obtained via the hydroselenation of either terminal or internal alkynes with benzeneselenol catalyzed by the nanosized Ni complexes has been carried out based on the experimental HMBC measurements and theoretical second order palarization propagator approach (SOPPA) calculations of their (77)Se-(1)H spin-spin coupling constants across double bond in combination with the energy-based theoretical conformational analysis performed at the MP2/6-311G** level. It has been found that studied phenylselanylalkenes adopt mainly skewed s-cis conformation with the noticeable out-of-plane deviations of the phenylselanyl and phenyl groups.

Stereochemical behavior of 77Se‐1H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane

“…As an example, 2 J (Se,H 4a ) ≈ −1 Hz and 2 J (Se,H 4e ) ≈ +30 Hz in 1 , or 3 J (Se,H 4a ) ≈ 1 Hz, whereas 3 J (Se,H 4e ) ≈ 13 Hz in 6 . With our previous results as basis, we expected that these differences were to be accounted for the selenium lone pair effect for geminal couplings and the Karplus‐type relationship for vicinal coupling constants.…”

“…In a number of our recent publications dealing with a combined theoretical and experimental study of 77 Se‐ 1 H spin‐spin coupling constants in divinyl selenide, selenophenes, selenosugars, derivatives of thiaselenetane, selenasilole, thiaselenole, thiaselenolane and dihydrothiaselenine, as well as in sterically crowded phenylselanylalkenes, a remarkable stereochemical behavior of 77 Se‐ 1 H geminal and vicinal couplings has been found, which is of major importance for stereochemical studies of organoselenium compounds. In the present paper, we continue these studies in the series of five derivatives of 2‐(pyrazol‐4‐yl)‐1,3‐diselenane 1–5 together with related 1,2‐diselenolane ( 6 ) being of particular synthetic interest as well as of potential practical application .…”

Computational 1H NMR: Part 1. Theoretical background

“…In the earlier publications, the LDBS scheme was successfully applied for the calculation of chemical shieldings (chemical shifts) at the Hartree–Fock and DFT levels in a number of simple benchmark molecules, in relatively large molecular systems, and even in the model forms of biological molecules such as simple dipeptides . Different LDBS schemes were also systematically used for the calculation of NMR parameters at the DFT and nonempirical levels of theory in a number of more recent publications by Rusakov and coworkers together with numerous related publications not cited herewith in view of their multiplicity.…”

Quantum chemical calculations of77Se and125Te nuclear magnetic resonance spectral parameters and their structural applications

“…Stereochemical study of five sterically crowded phenylselanylalkenes 29 – 33 (see Chart 4) has been carried out based on the experimental HMBC measurements and theoretical SOPPA calculations of their 77 Se– 1 H SSCCs across double bond in combination with the energy‐based theoretical conformational analysis performed at the MP2/6‐311G** level. [ 327 ]…”