Structural consequences of complexing of polybutadienyl lithium and its analogues with different electron donors

• Published in: Polymer science USSR 1987, Vol.29 (12), p.2774-2781
• Main Authors: Dolinskaya, E.R., Yerusalimskii, G.B., Rozinova, O.A., Kormer, V.A.
• Format: Article
• Language: English
• ISSN: 0032-3950; 1878-268X
• DOI: 10.1016/0032-3950(87)90193-6

The paper analyses the 1H NMR spectra of 1,1,4,4,4-pentadeuterocrotyllithium, the 1 : 1 adduct of perdeuteroisopropyl lithium and 1,1,4,4-tetradeuterobutadiene lithium and oligo(1,1,4,4-tetradeuterobutadien)yl lithium in toluene-d 8 and also in presence of small amounts of electron donors in a non-polar solvent. At the early stages of solvation of the lithium alkenyls only the signals of their syn-isomers undergo appreciable changes, the resonance of the H γ proton shifting to a weak field. In the case of crotyl lithium and oligobutadienyl lithium there is parallel partial anti-syn-isomerization of the terminal allyl group. Increase in the electron donor: alkenyl lithium ratio causes a heavy high field shift of the H γ signal accompanied by increase in the fraction of the anti-isomer of the compound studied. These effects are interpreted on the basis of quantum-chemical calculations of corresponding models.