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1,3-Diphospha-2-silaallylic Lithium Complexes and Anions:  Synthesis, Crystal Structures, Reactivity, and Bonding Properties

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journal contribution
posted on 13.05.1998, 00:00 by Dirk Lange, Elke Klein, Holger Bender, Edgar Niecke, Martin Nieger, Rudolf Pietschnig, Wolfgang W. Schoeller, Henri Ranaivonjatovo
Trichlorosilanes RSiCl3 (R = t-Bu, Mes, Cp*, Is, OAr) reacted with a 4-fold excess of lithium phosphanide ArPHLi (Ar = 2,4,6-tBu3C6H2) to form 1,3-diphospha-2-silaallylic complexes 3af. From the latter, the corresponding free allylic anions could be liberated by complexation of the lithium cation with [15]-crown-[5], as could be established on the basis of NMR spectra and X-ray structures. In addition, the bonding in the Li complexes was further investigated using ab initio calculations of double-ξ quality. The influence of cation solvation on the complex geometry was explored as well. The chemical reactivity of 1,3-diphospha-2-silaallylic anions with electrophiles (E = H+, ClPR‘R‘‘) was investigated. 1,3-Diphospha-2-silapropenes 4ad and 1,3,4-triphospha-2-silabutenes-(1) 5ae and 6a were prepared.