_P.-Powell-auth.-Principles-of-Organometallic-Chemistry-Springer-Netherlands-1988

The main Groups IV and V
fu- +
( + )[MePrPhAsCH 2 Ph] + (+)A- ~ ( + )[MePrPhAsCH 2 Ph] Br-
LiAIH 4
------> ( + )[MePrPhAs]
Optically active phosphines have been used as ligands in transition metal
complexes to induce asymmetric hydrogenation of suitable organic compounds
(p. 184).
The alkyl derivatives R 3 M (M = P, As, Sb, Bi) are all extremely susceptible to
oxidation. Me 3 P inflames in the air and even under more controlled conditions
gives a complex mixture of products with oxygen via radical chain reactions. The
triaryls, however, are air stable. Careful oxidation with aqueous hydrogen
peroxide or a suspension of mercury(II) oxide affords the oxides R,MO (not
M =Bi).
+ - RMgX
R 3 PX.X
Hzoz
R3 PO
+ ' -
R3 PR.X
R3 PS
Ct3PO
R3PF2
SF 4
R3PSe
The phosphorus-oxygen bond in R,P=O is conventionally written as a double
bond, implying pentavalent phosphorus (contrast R,N--> O in amine oxides; octet
expansion in nitrogen is forbidden). This implies that 3d orbitals of phosphorus
accept electron density from the oxygen lone pairs. This (2p-3d)n bonding can
involve both of the oxygen lone pairs and two orthogonal 3d orbitals of
phosphorus, leading to a cylindrically symmetrical n cloud about the P=O bond.
The bond energy E(P=O) in phosphine oxides in about 580 kJ mol- 1 ,
compared with E(P-0) in phosphites of 385 kJmol- 1 • The formation ofthis very
strong bond provides the driving force for many reactions of trivalent phosphorus
compounds. The tendency to form formal double bonds M =O decreases from P to
As to Sb. While arsine oxides are monomeric and may be written R 3 As=O,
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