Ferrocenylalkynes as ligands in transition metal complexes

Abstract

Several ferrocenylalkynes have been prepared and their reaction with dicobalt octacarbonyl led to the formation of [Co2(CO)6(μ-η2 ∶ η2-ethynylferrocene)] 1, [Co2(CO)6(μ-η2 ∶ η2-1,4-bis(ferrocenyl)butadiyne)] 2, [(Co2(CO)6)2(μ-η2 ∶ η2,μ-η2 ∶ η2-1,4-bis(ferrocenyl)butadiyne)] 3, [Co2(CO)6(μ-η2 ∶ η2-1-ferrocenylethynyl-2-hydro-1,2-dihydro-[60]fullerene)] 4, [Co2(CO)6(μ-η2 ∶ η2-1,1’-bis(phenylethynyl)ferrocene)] 5 and [(Co2(CO)6)2(μ-η2 ∶ η2,μ-η2 ∶ η2-1,1′-bis(phenylethynyl)ferrocene)] 6. The [Mo–Co]-alkyne adducts [MoCo(CO)5(η5-C5H5)(μ-η2 ∶ η2-ethynylferrocene)] 7 and [MoCo(CO)5(η5-C5H5)(μ-η2 ∶ η2-1,4-bis(ferrocenyl)butadiyne)] 8 were obtained from complexes 1, 2 and 3. The molecular structures of compounds 2, 3, 6 and 7 were determined by X-ray diffraction, only 6 has the cyclopentadienyl rings of the ferrocene unit eclipsed. The reaction of 1 with bis(diphenylphosphino)methane (dppm) and 1,1′-bis(diphenylphosphino)ferrocene (dppf) resulted in the formation of [Co2(CO)4(μ-η1 ∶ η1-dppm)(μ-η2 ∶ η2-ethynylferrocene)] 9 and [(Co2(CO)4)2(μ-η1 ∶ η1-dppf)2(η1-μ-η1-dppf)(μ-η2 ∶ η2-ethynylferrocene)2] 10, respectively. The reaction of HPPh2 with 7 gave the monosubstituted product [MoCo(CO)4(η5-C5H5)(PHPh2)(μ-η2,η2-ethynylferrocene)] 11. The bis(phosphido)-bridged complex [Co2(CO)6(μ-PPh2)2] undergoes regiospecific insertion with ethynylferrocene to give [Co2(CO)4{(μ-η4-PPh2CHCRC(O)}(μ-PPh2)] (R = ferrocene) 12, which was characterized by X-Ray diffraction and contains a five-membered metallacyclic ring.