Role of Phosphine Sterics in Strained Aminophosphine Chelate Formation

Abstract

The preparation of four-membered aminophosphine (PN) chelates from common metal precursors has largely evaded realization because of the ring strain associated with these species. We report a straightforward approach to the synthesis of such PN metallacycles using simple α-PN ligands analogous to the popular class of small-bite-angle diphosphinomethane ligands. It is demonstrated that bulky phosphine substituents are important to the formation of these chelates.

The underappreciated influence of ancillary halide on metal–ligand proton tautomerism

“…56 Additionally, work from both Grotjahn and Love has shown that larger phosphine substituents favor the formation of "strained" 4-membered PNchelates. 57,58 The bulky R-groups on phosphine are proposed to lower the ring strain through the Thorpe-Ingold effect compensating for the steric repulsion offered by the same Rgroups. Thus, overall, the sterics of the t Bu groups and the Thorpe-Ingold effect both favor the ionic [ LH Ir][X] species over the neutral [ LH Ir-X] species in these Ir-complexes.…”

Photochemical transformation of chlorobenzenes and white phosphorus into arylphosphines and phosphonium salts

“…3 , completely consumed within one hour under in situ NMR conditions, see also ESI, † S3 and Table S6) and the formation of Ph 3 P, [Ph 4 P]Cl and another intermediate (Int1). The structure of Int1 could be assigned based on a combination of its 31 P chemical shift, 1 H– 31 P HMQC experiments and comparison with literature data, 28 which suggest a TDAE skeleton that is coordinated to a Ph 2 P moiety via a methylene group ( Fig. 3 and see also ESI, † S6 and Fig.…”

Palladium Complexes of Methylene-Bridged P-Stereogenic, Unsymmetrical Diphosphines

“…The situation is different with the methylene-bridged diphosphine dppm, despite the fact that both ddpe and dppm were reported at the same time . Dppm and derivatives have also been widely used in coordination chemistry, and many complexes acting as bidentate species are known . In spite of this, the four-membered rings they form are quite strained and for this reason, unlike dppe, dppm shows a strong tendency to act as a bridging ligand between two metal centers, which are in close proximity .…”