Three-Coordinate Pd(0) with Rare-Earth Metalloligands: Synergetic CO Activation and Double P-C Bond Cleavage-Formation Reactions.

Abstract

Metalation of β-diketiminato rare-earth metal complexes LnacnacLn(PhNCH2PPh2)2 (Ln = Y, Yb, Lu) with (COD)Pd(CH2SiMe3)2 afforded three-coordinate Pd(0) complexes supported by two sterically less bulky phosphines and a Pd → Ln dative interaction. The Pd(0) center is prone to ligation with isonitrile and CO; in the latter case, the insertion of a second CO with the Y-N bond was assisted via a precoordination of CO on the Pd(0) center, which led to the formation of an anionic Pd(0) carbamoyl. The reaction of the Pd-Y complex with iodobenzene showed a remarkable double P-C bond cleavage-formation pathway within the heterobimetallic Pd-Y core to afford (Ph3P)2PdI(Ph), imine PhNCH2, and a β-diketiminato yttrium diiodide. In the related reaction of LnacnacY(PhNCH2PPh2)2 with (Ph3P)2PdI(Ph), the P-C bond cleavage following with a N-C bond formation was observed. Computational studies revealed a synergetic bimetallic mechanism for these reactions.