2‐Chloro‐1,3,2‐diazaphospholenes – A Crystal Structural Study

Abstract

Abstract A series of 2‐chloro‐1,3,2‐diazaphospholenes with different substitution patterns has been prepared from 1,4‐diazabutadienes according to a general synthetic methodology. Subsequent chloride abstraction with Lewis acids affords the corresponding 1,3,2‐diazaphospholenium salts. All products have been characterised spectroscopically and by single‐crystal X‐ray diffraction studies. A detailed analysis of trends in the structural parameters supports the interpretation that the unusual P–Cl bond lengthening in the diazaphospholenes is attributable to n(N)/σ*(P‐Cl) hyperconjugation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)