Diphosphinine Derivatives of Terpyridine: A New Class of Neutral π‐Accepting PNP‐Pincer Ligands

Abstract

The first diphosphinine analogue of terpyridine has been developed, which represents a new class of π‐accepting neutral PNP‐pincer ligands. Its electronic properties were evaluated by means of DFT calculations and the corresponding CuIBr complex was characterized crystallographically. The molecular structure revealed a distorted tetrahedral coordination geometry of the CuI center, due to an unusual coordination mode of the two phosphinine ligands (see graphic).

Synthesis, structure and π-delocalization of a phosphaalkenyl based neutral PNP-pincer

“…For this sequence the specific substitution pattern at the ketone and the phosphanide seem to be essential and for substituent combinations other than in I and II failure of this route has been reported [8]. In an alternative approach the phosphaalkene units are part of a phosphinine rings and the pincer III is obtained using the Märkl route to phosphinines via the corresponding bispyrylium salts [14].…”

Neutral Tridentate PNP Ligands and Their Hybrid Analogues: Versatile Non‐Innocent Scaffolds for Homogeneous Catalysis

“…We will not discuss these in detail here and refer the reader to the appropriate references. [42][43][44][45] Furthermore, Scheme 1. Formation of PNP ligands 12 R from readily available starting materials.…”

Recent Developments in the Chemistry of Pyridyl-functionalized, Low-coordinate Phosphorus Heterocycles

“…The modular approach for the synthesis of 2,4,6-triarylphosphinines has also been extended to the tridentate pyridyl-bridged diphosphinine 34, starting from commercially available 2,6-diacetylpyridine (Scheme 10). 47 This compound not only resembles a diphosphinine analogue of the well-known 2,2¤:6¤,2¤¤-terpyridine (tpy), but also represents a new class of neutral π-accepting PNP pincer ligands. Structural information on discrete terpyridineCu I X complexes (X = halide) have not been reported to date in the literature, although these species have been postulated in atom- transfer radical polymerization reactions.…”