Phospha‐Organic Chemistry: Panorama and Perspectives

Abstract

Since the beginning of the seventies, organophosphorus chemistry has been completely rejuvenated by the discovery of stable derivatives in which phosphorus has the coordination numbers one or two. The chemistry of these compounds mimics the chemistry of their all-carbon analogues. In this Review article this analogy is discussed for the phosphorus counterparts of alkenes, alkynes, and carbenes. In each case, the synthesis, reactivity, and coordination modes are briefly examined. Some special electronic configurations are also discussed, which include one-electron Pbond;P bonds, strained bonds, and aromatic systems. To conclude, some potential applications of this chemistry in the areas of molecular materials and homogeneous catalysis are presented.

Making the True “CP” Ligand

“…Potential applications arising from the use of C P as a bridging ligand between two metals, the incorporation of CP into coordination polymers and new materials, and the basic synthetic challenges of making C P have provided inspiration for decades. While phosphaalkynes (R À C P) have been known for some time, [1][2][3] the terminal MÀCP has only been reported as a transient species. [4,5] Other C-functionalized XÀCP compounds (X = R 3 Si, [6] R 2 N, [7,8] RO, [8] F, [9] Cl, [10] ), anionic species [XÀCP] À (X = R 3 B, [11] RN, [8] O, [12] S [13] ), and the cationic phosphonio phosphaalkyne [R 3 P À C P] + , [14] have been synthesized, but the vast majority of reports deal with tert-butyl, [15] adamantyl, [16] 2,4,6-trimethylphenyl [17] and 2,4,6-tri-tert-butylphenyl [18] phosphaalkynes.…”

Hydride Abstraction and Deprotonation – an Efficient Route to Low Coordinate Phosphorus and Arsenic Species

“…Transition metal stabilised phosphanylidene-σ 4 -phosphoranes (R 3 P=P(R)→ML n ) were first synthesised by Mathey and co-workers in 1990 [1] and have received attention as "phosphaWittig" reagents for the generation of P=C bonds, in which they act as phosphinidene (R-P) transfer reagents. [2][3][4][5][6] Free phosphanylidene-σ 4 -phosphoranes are rather reactive species, with only a handful of published examples where the compound is stabilised by extremely electron withdrawing substituents, [7,8] steric shielding, [9][10][11] or the combination of a rigid backbone and steric shielding. [12] Low co-ordinate arsenic chemistry is significantly less studied than that of phosphorus, with most attention being focused on arsaalkenes (R 2 C=AsR'), diarsenes (RAs=AsR), [13][14][15][16] and phosphine-and carbene-stabilised cationic species.…”

The CO/PC analogy in coordination chemistry and catalysis

“…[1] Though, this analogy is limited, it clearly appears that molecules which feature doubly and triply bonded carbon-phosphorus systems behave as their carbon 5 , Cr(CO) 5 , Fe(CO) 4 , lone pair 2: M = W(CO) 5 , Cr(CO) 5 ,…”