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(?-?2 ? ?2-ethynylferrocene)] 1, [Co2(CO)6(?-?2 ? ?2-1,4-bis(ferrocenyl)butadiyne)] 2, [(Co2(CO)6)2(?-?2 ? ?2,?-?2 ? ?2-1,4-bis(ferrocenyl)butadiyne)] 3, [Co2(CO)6(?-?2 ? ?2-1-ferrocenylethynyl-2-hydro-1,2-dihydro-[60]fullerene)] 4, [Co2(CO)6(?-?2 ? ?2-1,1?-bis(phenylethynyl)ferrocene)] 5 and [(Co2(CO)6)2(?-?2 ? ?2,?-?2 ? ?2-1,1?-bis(phenylethynyl)ferrocene)] 6. The [Mo?Co]-alkyne adducts [MoCo(CO)5(?5-C5H5)(?-?2 ? ?2-ethynylferrocene)] 7 and [MoCo(CO)5(?5-C5H5)(?-?2 ? ?2-1,4-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(?-?1 ? ?1-dppm)(?-?2 ? ?2-ethynylferrocene)] 9 and [(Co2(CO)4)2(?-?1 ? ?1-dppf )2(?1-?-?1-dppf )(?-?2 ? ?2-ethynylferrocene)2] 10, respectively. The reaction of HPPh2 with 7 gave the monosubstituted product [MoCo(CO)4(?5-C5H5)(PHPh2)(?-?2,?2-ethynylferrocene)] 11. The bis(phosphido)-bridged complex [Co2(CO)6(?-PPh2)2] undergoes regiospecific insertion with ethynylferrocene to give [Co2(CO)4{(?-?4-PPh2CHCRC(O)}(?-PPh2)] (R = ferrocene) 12, which was characterized by X-Ray diffraction and contains a five-membered metallacyclic ring.