[a student]

hi all
 As you know Nu can not attack the posphore for example imagine you have a P insted of a carbone in a carbonyl group, I know that the  nucleophiles won't attack the posphore atom but what is the reason?

[KritikalMass]

I don't think that there is even a functional group with those characteristics, is there 

[a student]

Sorry, I should insert the reaction before

[KritikalMass]

The chemical in your document is called phosphine oxide. You can search for it on the net. I think the reason the nucleophiles don't add to it the same way as to the carbonyl carbon is because phosphorous doesn't follow the octet rule. Also, some people, according to Wikipedia, describe it as existing in an ionic state as

(R)₃P⁺-O^-

Hope that helped!