Recent developments in the chemistry of non-trigonal pnictogen pincer compounds: from bonding to catalysis

Abstract

The combination of well-established meridionally coordinating, tridentate pincer ligands with group 15 elements affords geometrically constrained non-trigonal pnictogen pincer compounds. These species show remarkable activity in challenging element–hydrogen bond scission...

Contrasting E−H Bond Activation Pathways of a Phosphanyl‐Phosphagallene

“…In the context of main group compounds, N−H bond activation of ammonia is limited to low valent main group species,[ 28 , 29 , 30 , 31 , 32 ] and geometrically constrained T‐shaped phosphorus heterocycles. [ 33 , 34 ] To our knowledge, the only example of FLP‐facilitated NH 3 activation is an intermolecular pair which involves an N‐heterocyclic carbene and tris(pentafluorophenyl)borane. [35] When a solution of A in C 6 D 6 was exposed to 1 bar of ammonia, the solution immediately decolourised and two new signals in the 31 P{ 1 H} NMR spectrum were observed at 62.0 and −252.1 ppm ( 1 J P−P =566 Hz) corresponding to the ammonia activation product 1 c .…”

“…Ammonia is a more challenging substrate than primary amines. In the context of main group compounds, N−H bond activation of ammonia is limited to low valent main group species, [28–32] and geometrically constrained T‐shaped phosphorus heterocycles [33, 34] . To our knowledge, the only example of FLP‐facilitated NH 3 activation is an intermolecular pair which involves an N‐heterocyclic carbene and tris(pentafluorophenyl)borane [35] .…”

Bismuth Redox Catalysis: An Emerging Main-Group Platform for Organic Synthesis

“…Hence, a bidirectional Pn( n )/Pn( n +2) redox couple at group 15 elements should be viable. 15 , 16 Considering the foregoing pnictogen properties, the Radosevich group pioneered phosphorus redox catalysis via a P(III)/P(V) cycle. 17 By virtue of strained tridentate and bidentate ligands around phosphorus, the group overcame the large energetic gap between the frontier orbitals, thereby enabling redox catalysis.…”

“…In addition, by lowering the kinetic barrier of phosphine oxide reduction, numerous deoxygenative transformations via P(III)/P(V)=O cycling have been accomplished. 16 , 18 While the heavier congeners, arsenic and antimony, have a few examples of redox catalysis, 19 , 20 the heaviest stable element in group 15—bismuth—has had limited applications until recently, despite its low cost and low toxicity. 21 Indeed, bismuth has presented its candidacy as a versatile element in redox catalysis, given its rich redox chemistry and labile bonding nature that can enable new organic transformations and small molecule activation through Bi redox cycling.…”

Tris(2,4,6‐trimethylphenyl) phosphine with Aluminum Oxide Incorporated Polyethylene Separator for Lithium‐Ion Batteries

“…In this work, we suggest improving the cycling performance of high energy density‐based cells by incorporating a radical‐responsive functionalized separator. We propose tris(2,4,6‐trimethylphenyl) phosphine (TMPP) as the radical‐scavenging agent because the low oxidation state of phosphorous (P) element readily allows chemical binding with radical species 20,21 . However, a direct embedding of the radical‐scavenging agent onto a polyethylene (PE) separator via chemical modification is unlikely because the PE separator is only composed of hydrocarbon components, which are extremely stable chemical moieties 22,23 .…”