Palladium(II) Complexes of Homologated Ferrocene Phosphanylether and Thioether Ligands

Abstract

The reaction of [1′‐(diphenylphosphanyl)ferrocenyl]methanol/borane (1:1) with in situ formed N,N,N′,N′,S‐pentamethylisothiouronium iodide and sodium hydride, followed by removal of the borane protecting group with 1,4‐diazabicyclo[2.2.2]octane, afforded 1‐(diphenylphosphanyl)‐1′‐[(methylthio)methyl]ferrocene (3) as a new, homologated, hybrid phosphanylferrocene ligand. Compound 3 and the congeneric phosphanyl ether 2 were studied as ligands in PdII complexes. When treated with [PdCl2(MeCN)2] in a Pd/ligand ratio of 1:1, compound 3 furnished a mixture of two Pd complexes, including the ligand‐bridged dimer [{µ(P,S)‐3}PdCl2]2 (6), which was structurally characterized. Upon increasing the amount of ligand to 2 equiv., a similar reaction produced the bis(phosphane) complex [PdCl2(3‐κP)2] (7). Bridge‐cleavage reactions of the dipalladium complex [(LNC)Pd(µ‐Cl)]2 {LNC = 2‐[(dimethylamino‐κN)methyl]phenyl‐κC1} with donors 3 and 2 proceeded in a uniform manner to give the corresponding phosphane complexes [(LNC)PdCl(3‐κP)] (8) and [(LNC)PdCl(2‐κP)] (9). Conversely, removing the Pd‐bonded chloride from these complexes with AgClO4 generated the bis(chelate) complex [(LNC)Pd(3‐κ2P,S)] (10) and the aqua complex [(LNC)Pd(H2O)(2‐κP)] (11), respectively, both of which could be converted back into their precursors by adding Bu4NCl. The structures of the complexes 6–11 (some in solvated form) were determined by single‐crystal X‐ray diffraction analysis.