A new chiral metalladiphosphine for early–late chemistry. Crystal structure of a D-camphor-based zirconium enolato phosphine and rearrangement of heterobimetallic Zr/Pd complexes

Abstract

The bis(phosphinoenolato) zirconocene 2, prepared from the phosphino camphor derivative 3-exo-PPh₂C₁₀H₁₅O 1, represents the first C₂-symmetric chiral diphosphine containing an early transition metal centre tethered to the phosphino groups via an enolato linkage. It allows the selective assembly of Lewis-acid early–late bimetallic combinations, as exemplified with the Zr/Cu and Zr/Ag complexes 4 and 5. The monophosphinoenolato titanocene 3 was also prepared. Reactions of 2 or 3 with [Pd(dmba)(μ-Cl)]₂ (dmba = o-C₆H₄CH₂NMe₂) or [PdCl₂(SEt₂)₂] led to complete transfer of the functional ligand to the Pd(II) centre, with formation of [(dmba)Pd(PPh₂C₁₀H₁₄O)] 6 or cis-[Pd(PPh₂C₁₀H₁₄O)₂] 8 and [Cp₂ZrCl₂]/[Cp₂TiCl₂], respectively. A heterobimetallic Zr/Pd intermediate complex 10 of this rearrangement could be detected. Complexes 6 and 8 were prepared independently by reaction of 1 with [Pd(dmba)(μ-Cl)]₂ or [Pd(SEt₂)₂Cl₂], respectively, which first afforded complexes 7 and 9 which were then treated with KH. The crystal structures of 2, 6 and 8·THF·H₂O have been determined by X-ray diffraction.