Patent ID: 7696349

Claim:
A ligand selected from among compounds of the formulae I.i to I.iii and the tautomers thereof, where b is 0 or 1, Pn is P, As or Sb, and R1 and R2 are bridged so that they form a pnicogen-comprising group of the formula wherein r and s are independently of another 0 or 1, D together with the phosphorus atom and the oxygen atom(s) to which it is bound forms a 4- to 8-membered heterocycle which may be fused with one. two or three cycloalkyl, heterocycloalkyl, aryl and/or hetaryl groups. where the fused-on groups may each independently of one another bear one, two, three or four substituents selected from among alkyl, alkoxy, halogen, sulfonate, NE4E5, alkylene-NE4E5, nitro, cyano and carboxylate, and/or D may bear one, two, three or four substituents selected from among alkyl, hydroxy, alkoxy, optionally substituted cycloalkyl and optionally substituted aryl, and/or D may be interrupted by 1, 2 or 3 optionally substituted heteroatoms, and R 6 to R 9 are each, independently of one another, hydrogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, aryl, heteroaryl, acyl, halogen, C 1 -C 4 -alkoxycarbonyl or carboxylate, where two vicinal radicals R 6 to R 9 may also form a fused ring system, and R a and R h are each hydrogen, alkyl, cycloalkyl or aryl, and R a can also be acyl.