Patent ID: 7081536

Claim:
A compound of formula I wherein X is oxygen, sulfur, selenium or NQ, wherein Q is unsubstituted or substituted aryl, or alkyl or substituted alkyl; n is 0, 1, 2, 3or 4; A 1 and A 2 are each an organic radical capable of bonding to phosphorus, selected from the group consisting of unsubstituted or substituted alkyl, unsubstituted or substituted aryl, unsubstituted or substituted heterocyclyl, unsubstituted or substituted cycloalkyl, or —N(D) 2 wherein D 2 is alkyl or substituted alkyl; or A 1 and A 2 together with the bonding phosphorus atom form a ring, which may be unsubstituted or substituted; Y, Y′, Y″ and Y′″ are each independently of the other hydrogen or alkyl, substituted alkyl, aryl-lower alkyl wherein the aryl radical is unsubstituted or substituted, and heterocyclyl-lower alkyl wherein the heterocyclyl radical is unsubstituted or substituted, unsubstituted or substituted aryl, or unsubstituted or substituted heterocyclyl, at least one of the radicals Y, Y′, Y″ or Y′″ being one of the mentioned radicals with the exception of hydrogen; and Z, when present, is a substituent, it being possible when a plurality of substituents Z is present for those substituents to be selected independently of one another; or a mixture of such compounds.