The synthesis of heteroleptic phosphines

Abstract

Heteroleptic phosphines (R2PR(1)) are a class of essential ligands for inorganic and organometallic chemistry. However, the syntheses of these phosphines are often fraught with laborious synthetic hurdles. Consequently, a renewed interest in innovative synthetic methods to access heteroleptic phosphines is emerging. This Perspective presents an overview of modern synthetic approaches to heteroleptic phosphines as well as a discussion of the strengths and limitations of these synthetic methods. A major emphasis is placed on simple and direct routes to phosphines and significant synthetic innovations for P-C bond-forming reactions.

Tris(imidazolin‐2‐ylidenamino)phosphine: A Crystalline Phosphorus(III) Superbase That Splits Carbon Dioxide

“…In homogeneous transition‐metal catalysis, the optimization of the catalytic center by varying the ligand properties is a powerful tool to tune activity and selectivity . Among the various ligand types phosphines are one of the most utilized ancillary ligands, as their steric and electronic properties can be easily adjusted in a predictable manner by modification of the substituents attached to the phosphorus atom . A quantitative description of the phosphine's stereoelectronic properties is most commonly provided by the Tolman electronic parameter (TEP) and cone angle .…”

“…[3] Aq uantitative description of the phosphine's stereoelectronicp roperties is most commonly provided by the Tolman electronic parameter (TEP) and cone angle. [4] The classical boundaries of the electron-releasing character of organophosphinesh ave been recently expanded by Alcarazo's cationic phosphines that act as very strong p-acceptor ligands, [5] while Carrow et al showed that tri(1-adamantyl)phosphine is significantly more donating than P(tBu) 3 (Figure 1). [6] Yang recently showed that proazaphosphatranes (also knowna sV erkade'ss uperbases) [7] have comparable TEP values to P(tBu) 3 (Figure 1).…”

“…[1] Among thev arious ligand types phosphines are one of the most utilized ancillary ligands, [2] as their steric and electronic properties can be easily adjusted in ap redictable manner by modification of the substituents attachedt ot he phosphorusa tom. [3] Aq uantitative description of the phosphine's stereoelectronicp roperties is most commonly provided by the Tolman electronic parameter (TEP) and cone angle. [4] The classical boundaries of the electron-releasing character of organophosphinesh ave been recently expanded by Alcarazo's cationic phosphines that act as very strong p-acceptor ligands, [5] while Carrow et al showed that tri(1-adamantyl)phosphine is significantly more donating than P(tBu) 3 (Figure 1).…”

“…[4] The classical boundaries of the electron-releasing character of organophosphinesh ave been recently expanded by Alcarazo's cationic phosphines that act as very strong p-acceptor ligands, [5] while Carrow et al showed that tri(1-adamantyl)phosphine is significantly more donating than P(tBu) 3 (Figure 1). [6] Yang recently showed that proazaphosphatranes (also knowna sV erkade'ss uperbases) [7] have comparable TEP values to P(tBu) 3 (Figure 1). [8] Amongt he varioust ypes of nonionic superbases, [9] proazaphosphatranes are unique because they become protonated at the phosphorus atom.…”

Synthesis, Structure and Nickel Carbonyl Complexes of Dialkylterphenyl Phosphines

“…By and large, during the second half of the past century, studies on transition metal complexes focused on alkyl and aryl phosphines such as PMe 3 , P i Pr 3 , P( c ‐C 6 H 11 ) 3 , PPh 3 and others. Notwithstanding the versatility of these ligands, relatively little progress was made on the synthesis of monodentate phosphines until fairly recently . Some twenty years ago, Buchwald and co‐workers demonstrated that when bound to palladium, dialkylbiaryl phosphines were able to catalyse with high proficiency C−C and C−N coupling reactions of aryl halides, including unactivated aryl chlorides .…”