[faust]

Hello.

I have a ligand in a publication which is : PPF-P(tBu)2 (same as JOSIPHOS but with 2 t-Bu in place of 2 Cy).

And they write : ent-PPF-P(tBu)2. What does "ent" mean?

Thank you

[Albert]

You know E-Z nomenclature, don't you? E is to trans as Z is to cis.

E comes from German entgegen, which means (more or less) 'contrary to'; Z from zusammen, 'together'.

In my opinion, Ent stands for E.

[faust]

but in this ligand I don't have any double bond...

[Albert]

Could you draw them?

[movies]

Usually that means they are using the enantiomer of whatever is drawn in the picture.  So, if the draw (S)-BINAP and label it as 1, then ent-1 is (R)-BINAP.

[faust]

Thank you very much for your help