Synthesis of pyrrole-based PSiP pincer ligands and their palladium, rhodium, and platinum complexes

Abstract

Palladium, rhodium and platinum bis(phosphino)silyl pincer complexes featuring pyrrole-based linkers were synthesized and their properties studied.

Dimeric Rh Complexes Supported by a Bridging Phosphido/Bis(Phosphine) PPP Ligand

“…Most tellingly, there were two resonances in each 31 P­{ 1 H} NMR spectrum in a 2:1 ratio, which displayed coupling to each other ( 2 J P–P = 40–44 Hz) as well as to 103 Rh ( 1 J P–Rh = 122–124 and 285–291 Hz). The smaller 1 J P–Rh value belongs to the outer -PPr i 2 arms and is generally in the range observed for (PXP)­Rh pincer complexes with similar substituents on P. ,,− The greater 1 J P–Rh value corresponds to the central P atom, which bears three heteroatoms and is trans to a halide. The chemical shifts of the 31 P NMR resonances of the −PPr i 2 arms in 3a – d fall within the narrow range of 37.7–38.2 ppm.…”

“…We recently became interested in using 1,2-pyrrolediyl as an alternative linker and reported complexes of PBP and PAlP pincer ligands, as well as PSiP ligands jointly with the Johnson group . Here, we report on the synthesis of a pyrrole-derived PPP pincer and its Rh complexes.…”

Tetrelanes versus Tetrylenes as Precursors to Transition Metal Complexes Featuring Tridentate PEP Tetryl Ligands (E=Si, Ge, Sn)

“…Diphenyl‐ and diisopropyl‐2‐pyrrolylphosphane have been recently used to prepare silanes of type E (Scheme 3) (from the corresponding lithium salts and SiCl 2 MeH) together with some rhodium, palladium and platinum derivatives (from reactions with [Rh 2 Cl 2 (cod) 2 ], [RhH(CO)(PPh 3 ) 3 ], [Pd 2 Cl 2 (allyl) 2 ] and [PtCl 2 (cod)], respectively) (Scheme 3). [57] These pyrrolyl‐derived PSiP silyl ligands are sterically similar but weaker donors than their analogues derived from silanes of type C .…”

Comparative Analysis of the Donor Properties of Isomeric Pyrrolyl Phosphine Ligands

“…16,17 2-(Phosphino)pyrroles have also been used as bridging ligands in multimetallic complexes 18−20 and as components of pincer ligands. 21,22 3-(Phosphino)pyrrole-based ligands have received far less attention, but their exceptionally strong donor ability has been recently investigated. Despite the importance of phosphinopyrroles in coordination chemistry and catalysis, to the best of our knowledge, a comprehensive and comparative analysis of the donor properties of 1-and 2-(phosphino)pyrroles and their impact on their metal complexes has yet to be undertaken.…”

“…This class of ligand has been employed in carbonylation, C–H functionalization, hydrogenation, and ethanol upgrading reactions . Perhaps the most notable 2-(phosphino)­pyrroles are the highly modular N -aryl 2-(phosphino)­pyrrole cataCXium ligands ( D ), which enable a variety of efficient cross-coupling reactions. , 2-(Phosphino)­pyrroles have also been used as bridging ligands in multimetallic complexes − and as components of pincer ligands. , 3-(Phosphino)­pyrrole-based ligands have received far less attention, but their exceptionally strong donor ability has been recently investigated …”