No abstract

While research on lanthanide (Ln) complexes with silyl ligands is receiving growing attention, significantly unbalanced efforts have been devoted to different Ln elements. In comparison with the intense investigations on Ln elements such as Sm and Yb, the chemistry of silyl lanthanum and cerium complexes is much slower to develop, and no solid-state structure of a silyl lanthanum complex has been reported so far. In this research, four types of ate complexes, including [(DME)3Li]­[Cp3LnSi­(H)­Mes2], [(18-crown-6)­K]­[Cp3LnSi­(CH3)­Ph2], [(DME)3Li]­[Cp3LnSiPh3], and [(12-crown-4)2Na] [Cp3LnSi­(Ph)2Si­(H)­Ph2] (Ln = La, Ce), were synthesized by reacting [(DME)3Na]­[Cp3La­(μ-Cl)­LaCp3] or Cp3Ce­(THF) with alkali metal silanides. All of the synthesized silyl Ln ate complexes were structurally characterized. La–Si bond lengths are in a range of 3.1733(4)–3.1897(10) Å, and the calculated formal shortness ratios of the La–Si bonds (1.071.08) are comparable to those in the reported silyl complexes having other Ln metal centers. The Ce–Si bond lengths (3.1415(6)–3.1705(9) Å) are within the typical range of reported silyl cerium ate complexes. 29Si solid-state NMR measurements on the diamagnetic silyl lanthanum complexes were conducted, and large one-bond hyperfine splitting constants arising from = 7/2) were resolved. Computational studies on these silyl lanthanum and cerium complexes suggested the polarized covalent feature of the Ln–Si bonds, which is in line with the measured large 1 J 139La–Si splitting constants.

Metalation of β-diketiminato rare-earth metal complexes L nacnac Ln(PhNCH 2 PPh 2 ) 2 (Ln = Y, Yb, Lu) with (COD)Pd(CH 2 SiMe 3 ) 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 (Ph 3 P) 2 PdI(Ph), imine PhNCH 2 , and a β-diketiminato yttrium diiodide. In the related reaction of L nacnac Y(PhNCH 2 PPh 2 ) 2 with (Ph 3 P) 2 PdI(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.

No abstract

No abstract