Tris(tetramethylguanidinyl)phosphine: The Simplest Non‐ionic Phosphorus Superbase and Strongly Donating Phosphine Ligand

Abstract

We report the synthesis and properties of the much sought-after tris(1,1,3,3-tetramethylguanidinyl) phosphine P(tmg) 3 , a crystalline, superbasic phosphine accessible through a short and scalable procedure from the cheap and commercially available bulk chemicals 1,1,3,3-tetramethylguanidine, tris(dimethylamino)-phosphine and phosphorus trichloride. The new phosphine exhibits exceptional electron donor properties and readily forms transition metal complexes with gold(I), palladium(II) and rhodium(I) precursors. The formation of zwitterionic Lewis base adducts with carbon dioxide and sulfur dioxide was explored. In addition, the complete series of phosphine chalcogenides was prepared from the reaction of P(tmg) 3 with N 2 O and the elemental chalcogens.

Free Metallophosphines: Extremely Electron‐Rich Phosphorus Superbases That Are Electronically and Sterically Tunable**

“…are early representatives of rare examples of strong donor phosphines [10] . In 2017, the Dielmann group described the isolation of imidazolin‐2‐ylidenaminophosphines (IAPs) C with high basicity, [11] and more recently they reported a tris(tetramethylguanidinyl)phosphine [12] . In 2018, Gessner et al.…”

“…[10] In 2017, the Dielmann group described the isolation of imidazolin-2-ylidenaminophosphines (IAPs) C with high basicity, [11] and more recently they reported a tris(tetramethylguanidinyl)phosphine. [12] In 2018, Gessner et al disclosed a series of ylide-functionalized phosphines (YPhos) D [13] and their superior performance in TM catalysis. [13a, 14] In 2019, Sundermeyer and co-workers showcased a fascinating class of electron-rich phosphazenyl phosphines (PAPs), [15] one of which (E) represents the most electron-rich uncharged phosphorus Brønsted and Lewis base to date.…”

Tri(N-carbazolyl)phosphine Gold(I) Complexes: Structural and Catalytic Activity Studies

“…In 2017, Clavier et al reported phosphorous triamide-coordinated gold­(I) complexes bearing Verkade′s superbase as a ligand (Figure A2), and recently, Dielmann et al. reported gold­(I) complexes bearing highly electron-rich pyridinylidenaminophosphines and tris­(tetramethylguanidinyl)­phosphine as ligands (Figure A3,A4) . These examples testify that phosphorous triamide-coordinated gold­(I) complexes are convenient to prepare, stable at ambient conditions, and have tunable stereoelectronic properties with varying N -substituents.…”

Phosphine Modulation for Enhanced CO2 Capture: Quantum Mechanics Predictions of New Materials

“…Additionally, 2.2a has already been synthesized and characterized, making its use for CO 2 transformation quite feasible. 28 The TMG ligand (1,1,3,3-tetramethylguanidinium) features four methyl groups bound through two sp 2 nitrogens. A natural extension of the TMG ligand is to swap out the methyl moieties for functional groups capable of hydrogen bond donation to the oxygens of the incoming CO 2 .…”

“…The P­( i Pr)­(NI i Pr) 2 complex has exceptional binding to CO 2 ; however, 2.2 binds CO 2 −1.5 kcal/mol more strongly. Additionally, 2.2a has already been synthesized and characterized, making its use for CO 2 transformation quite feasible …”