Phosphinooxazolines as assembling ligands in heterometallic complexes

It is shown that phosphinooxazolines such as (2-oxazoline-2-ylmethyl)diphenylphosphine 1 can be used as P,N assembling ligands for the synthesis of heterometallic complexes. These were obtained in a stepwise manner from the iron carbonyl complexes containing one, [Fe(CO)(4)PCH2-oxazoline-P)] 2, or two, trans-[Fe(CO)(3)(PCH2-oxazoline-P)(2)] 6, P-bound phosphin ooxazo line ligands. These metalloligands were then reacted with metal complexes. With 2, complete ligand transfer from Fe to the second metal (Pd) was sometimes observed. The metal-metal bonded complex [(OC)(4)Fe(mu-PCH2-oxazoline-P,N)PdCl2] 3 was of limited stability, whereas the trinuclear complex trans-(OC)(4)Fe(mu-PCH2-oxazoline-P,N)}(2)CoCl2] 4, in which 2 functions as a N-donor metalloligand toward the tetrahedral Co(II) centre, was stable and could be fully characterised by X-ray diffraction. This complex catalyses the oligomerization of ethylene to give linear alpha-olefins in the range C-4-C-26, with a maximum of the Schulz-Flory distribution around C-6. The complex [{(OC)(4)Fe(mu-PCH2-oxazoline-P,N)}(2)HgI2]5 was also prepared from 6. With the metalloligand 6, the Fe-->Pd and Fe-->Co metal-metal bonded compounds trans-[(OC)(3)Fe(mu-PCH2-oxazoline-P,N)(2)Pd(NCMe)](BF4)(2) 8 and trans-[(OC)(3)Fe(mu-PCH2-oxazoline-P,N)(2)CoCl2]9 were obtained.