Unusual Ligand Transformation Mediated by Chromium(III): Hydrolytic Disintegration of a [PNP] Hybrid Ligand with CH₃CN Insertion

Concomitant reaction among coordinated CH3CN and a bidentate [P(N)P] aminodiphosphine ligand in [Ph2PN(R)PPh2]CrCl3(CH3CN) (R = Cy, Ph) with H2O results in a tridentate [ONO] amino-α-diphosphoryl ligand in [Ph2P(O)C(CH3)(NH2)P(O)Ph2]CrCl3. The latter releases the free ligand upon treatment with excess water or gives a cationic complex, {[Ph2P(O)C(CH3)(NH2)P(O)Ph2]CrCl2[P(O)(H)Ph2]}+SbF6−, when treated with AgSbF6. All the new compounds have been crystallographically established. The catalytic activities of these complexes toward ethylene oligomerization and polymerization are described and compared.