Cyclopalladated compounds derived from ferrocenylimines. Crystal strcuture of [Pd{(η5-C5H5)Fe[η5-C5H3CHN(CH2)2Ph]}Cl(PEt3)]

Abstract

Reactions of ferrocenylimines of general formula [Fe(η⁵-C₅H₅){η⁵-C₅H₄CHN(CH₂)_nPh}](n= 1 1a or 2 1b) with palladium(II) salts have been studied. The dimeric cyclopalladated complexes [{[graphic omitted](CH₂)_nPh}]Cl}₂]2a and 2b were obtained when the reactions were carried out in the presence of sodium acetate and using Na₂[PdCl₄] as starting material. Addition of phosphine ligands PR₃(R = Ph or Et) or 1,2-bis(diphenylphosphino)ethane (dppe) to acetone suspensions of these dinuclear compounds produced the more soluble mononuclear complexes [[graphic omitted](CH₂)_nPh]}Cl(PR₃)] with R = Ph (3a and 3b) and Et (4a and 4b) and [[graphic omitted](CH₂)_nPh]}(dppe)]Cl (5a and 5b). Proton and ³¹P NMR spectroscopic studies on these compounds confirm the formations of endo five-membered metallocycles. Mössbauer spectra of compounds 1b–5b have also been recorded. The first crystal structure of a cyclopalladated complex derived from ferrocenylimines has been determined. The compound [[graphic omitted]CH₂CH₂Ph)}Cl(PEt₃)]4b is monoclinic, space group P2₁/a, with a= 15.944(3), b= 12.425(2), c= 12.682(2)Å, β= 100.19(2)° and Z= 4. The structure confirms the formation of an endo five-membered metallocycle on the ferrocene moiety.