Phosphinines as ligands in homogeneous catalysis: recent developments, concepts and perspectives

Abstract

Phosphinines belong to an intriguing class of phosphorus-containing heterocycles with interesting steric, electronic and coordinating properties. This article focuses on recent developments, concepts and perspectives in the field of phosphinines and phosphinine-based ligands and their application as ligands in homogeneous catalytic reactions.

PdII and PtII Complexes of 2‐(2′‐Pyridyl)‐4,6‐diphenylphosphinine: Synthesis, Structure, and Reactivity

“…Upon concentrating the dark-red solutions, the products precipitated and were isolated as brightpurple powders in 71 (Pd) and 76 % (Pt) yields, respectively. According to the mechanism of the addition reaction proposed by Venanzi and co-workers [9] for the reaction of CH 3 …”

“…Strikingly, the reaction of [PdCl 2 A C H T U N G T R E N N U N G (1H·OCH 3 )] with the chelating diphosphine DPEphos at room temperature in CH 2 Cl 2 led quantitatively to [PdCl 2 A C H T U N G T R E N N U N G (DPEphos)] and phosphinine 1 by elimination of CH 3 OH and rearomatization of the phosphorus heterocycle.…”

“…[11][12][13] It turned out that 2-(2'-pyridyl)-4,6-diphenylphosphinine (1, Scheme 1) is readily available from the corresponding pyridyl-functionalized pyrylium salt and PA C H T U N G T R E N N U N G (SiMe 3 ) 3 and we have recently investigated its coordination chemistry with Rh I . [14,15] We anticipated that the additional phenyl group at the 6-position of the heterocyclic framework might lead to a kinetic stabilization of the corresponding metal complexes as the P = C double bond is sterically more shielded for addition reactions.…”

“…[1] The replacement of a pyridine unit by a p-accepting l 3 -phosphinine [2,3] entity leads to 2-(2'-pyridyl)phosphinine, a semi-equivalent of bpy containing a low-coordinated "soft" phosphorus and a "hard" nitrogen heteroatom. Such chelates are intriguing bidentate hybrid ligands, which were first described by Mathey and co-workers in 1982 with the synthesis of 2-(2'-pyridyl)-4,5-dimethylphosphinine (NIPHOS, Scheme 1).…”

Crystal Structures of the Gold(I) Phosphinine Complexes [AuCl(C5H2P-2,6-Me2-4-Ph)] and [AuCl(C5H2P-2,4,6-Ph3)]

“…Homologous molybdenum and tungsten pentacarbonyl complexes were structurally characterised by the groups of Ashe [17] and Mathey [18]. This development culminated in the synthesis and structural characterisation of [M(κP-C 5 H 5 P) 6 ] (M = Cr, Mo, W), the phosphinine analogue of the group 6 metal hexacarbonyl complexes, by Elschenbroich and coworkers [19,20]. The first structurally characterised κP-phosphinine complexes with transition metals not belonging to group 6 were published in the early 1990s [21,22].…”