Bisphosphines as bidentate ligands

A ligand represented by formula (I),

• wherein R3 and R4 are independently selected from the group consisting of (C1-C8)-alkyl, (C2-C8)-alkoxyalkyl, (C6-C18)-aryl, (C7-C19)-aralkyl, (C3-C18)-heteroaryl, (C4-C19)-heteroaralkyl, (C1-C8)-alkyl-(C6-C18)-aryl, (C1-C8)-alkyl-(C3-C18)-heteroaryl, (C3-C8)-cycloalkyl, (C1-C8)-alkyl-(C3-C8)-cycloalkyl, and (C3-C8)-cycloalkyl-(C1-C8)-alkyl, and
• R1 and R2 represent a (C3-C5)-alkylene bridge mono or polysubstituted with (C1-C8)-alkyl, HO—(C1-C8)-alkyl, (C1-C8)-alkoxy, (C2-C8)-alkoxyalkyl, (C6-C18)-aryl, (C7-C19)-aralkyl, (C1-C8)-alkyl-(C6-C18)-aryl, (C3-C8)-cycloalkyl, (C1-C8)-alkyl-(C3-C8)-cycloalkyl or (C3-C8)-cycloalkyl-(C1-C8)-alkyl, optionally linked to a polymer enlargement, or
• R1, R2, R3 and R4 represent a (C3-C5)-alkylene bridge mono or polysubstituted with (C1-C8)-alkyl, HO—(C1-C8)-alkyl, (C1-C8)-alkoxy, (C2-C8)-alkoxyalkyl, (C6-C18)-aryl, (C7-C19)-aralkyl, (C1-C8)-alkyl-(C6-C18)-aryl, (C3-C8)-cycloalkyl, (C1-C8)-alkyl-(C3-C8)-cycloalkyl or (C3-C8)-cycloalkyl-(C1-C8)-alkyl, optionally linked to a polymer enlargement;
• A is represented by
• wherein
• Q is selected from the group consisting of O, NH and NR*;
• and
• R* is selected from the group consisting of H, (C1-C8)-alkyl, (C6-C8)-aryl, (C7-C19)-aralkyl, (C1-C8)-alkyl-(C6-C18)-aryl, (C3-C8)-cycloalkyl, (C1-C8)-alkyl-(C3-C8)-cycloalkyl, (C3-C8)-cycloalkyl-(C1-C8)-alkyl, and a link to a polymer enlargement.