Chelating and bridging diphosphinoamine (PPh 2) 2N( i Pr) complexes of copper(I)

• Published in: Journal of organometallic chemistry Vol. 694; no. 7; pp. 1144 - 1152
• Main Authors: Ahuja, Ritu, Nethaji, Munirathinam, Samuelson, Ashoka G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2009
• Subjects: Binding mode; Copper(I); Diphosphinoamine; Nuclearity; Short bite ligand; Binding mode; Copper(I); Nuclearity; Diphosphinoamine; Short bite ligand
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2008.11.028

Bis(diphenylphosphino)isopropylamine is quite flexible as a ligand and adopts either a chelating or bridging mode to facilitate the formation of a wide variety of complexes with copper(I). The ligand bis(diphenylphosphino)isopropylamine (dppipa) has been shown to be a versatile ligand sporting different coordination modes and geometries dictated by copper(I). Most of the molecular structures were confirmed by X-ray crystallography. It is found in a chelating mode, in a monomeric complex when the ligand to copper ratio is 2:1. A tetrameric complex is formed when low ratios of ligand to metal (1:2) were used. But with increasing ratios of ligand to metal (1:1 and 2:1), a trimer or a dimer was obtained depending on the crystallization conditions. Variable temperature 31P{ 1H} NMR spectra of these complexes in solution showed that the Cu–P bond was labile and the highly strained 4-membered structure chelate found in the solid state readily converted to a bridged structures. On the other hand, complexes with the ligand in a bridging mode in the solid state did not form chelated structures in solution. The effect of adding tetra-alkylammonium salts to solutions of various complexes of dppipa were probed by 31P{ 1H} NMR and revealed the effect of counter ions on the stability of complexes in solution.