Heterometallic Clusters with Cerium-Transition-Metal Bonding Supported by Nitrogen-Phosphorus Ligands.

Ligands are known to play a crucial role in the construction of complexes with metal-metal bonds. Compared with metal-metal bonds involving d-block transition metals, knowledge of the metal-metal bonds involving f-block rare-earth metals still lags far behind. Herein, we report a series of complexes with cerium-transition-metal bonds, which are supported by two kinds of nitrogen-phosphorus ligands N[CH 2 CH 2 NHP i Pr 2 ] 3 ( VI ) and PyNHCH 2 PPh 2 ( VII ). The reactions of zerovalent group 10 metal precursors, Pd(PPh 3 ) 4 and Pt(PPh 3 ) 4 , with the cerium complex supported by VI generate heterometallic clusters [N{CH 2 CH 2 NP i Pr 2 } 3 Ce(μ-M)] 2 (M = Pd, 2 and M = Pt, 3 ) featuring four Ce-M bonds; meanwhile, the bimetallic species [(PyNCH 2 PPh 2 ) 3 Ce-M] (M = Ni, 5 ; M = Pd, 6 ; and M = Pt, 7 ) with a single Ce-M bond were isolated from the reactions of the cerium precursor 4 supported by VII with Ni(COD) 2 , Pd(PPh 3 ) 4 , or Pt(PPh 3 ) 4 , respectively. These complexes represent the first example of species with an RE-M bond between Ce and group 10 metals, and 2 and 3 contain the largest number of RE-M donor/acceptor interactions ever to have been observed in a molecule.