Abstrakt
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 Pd-II 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 [{mu(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-P)2] (7).
Bridge-cleavage reactions of the dipalladium complex [(L-NC)Pd(mu-Cl)]2 {L-NC = 2-[(dimethylamino-N)methyl]phenyl-C-1} with donors 3 and 2 proceeded in a uniform manner to give the corresponding phosphane complexes [(L-NC)PdCl(3-P)] (8) and [(L-NC)PdCl(2-P)] (9). Conversely, removing the Pd-bonded chloride from these complexes with AgClO4 generated the bis(chelate) complex [(L-NC)Pd(3-P-2,S)]ClO4 (10) and the aqua complex [(L-NC)Pd(H2O)(2-P)]ClO4 (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.