Stabilization of a Diphosphagermylene through pπ–pπ Interactions with a Trigonal‐Planar Phosphorus Center

Abstract

Abstract N‐Heterocyclic carbenes and their heavier homologues are, in part, stabilized by delocalization of the N lone pairs into the vacant p‐orbital at carbon (or a heavier Group 14 element center). These interactions are usually absent in the corresponding P‐substituted species, owing to the large barrier to planarization of phosphorus. However, judicious selection of the substituents at phosphorus has enabled the synthesis of a diphosphagermylene, [(Dipp) 2 P] 2 Ge, in which one of the P centers is planar (Dipp=2,6‐diisopropylphenyl). The planar nature of this P center and the correspondingly short PGe distance suggest a significant degree of PGe multiple bond character that is due to delocalization of the phosphorus lone pair into the vacant p‐orbital at germanium. DFT calculations support this proposition and NBO and AIM analyses are consistent with a GeP bond order greater than unity.