Synthesis, Metallation and Complexes of Annulated 1H-1,3-Azaphospholes

Abstract

We studied the complex chemical behavior of neutral and anionic annulated 1 H-1,3-azaphospholes. 2-PhosphaindoIizines, synthesized from pyridinium salts and PCl₃ /Et₃N, reacted with (CO)₅M (THF) (M ˭ Cr, Mo, W) yielding (η-phosphaindolizine)M(CO)₅ complexes. Comparison of ³¹P, H and ³¹C-NMR data of free ligands and complexes allows to characterize donor and acceptor properties of this ligand type. According to ³C coordination shifts, π-back donation has a rather local effect. An X-ray structure analysis of a LCr(CO)₅ complex and of the respective ligand L shows a more effective delocalization with nearly

equal P-C bond lengths in the complex-bound ligand.