A General Pathway to Heterobimetallic Triple-Decker Complexes

Abstract

A systematic study on the reactivity of the triple-decker complex [(Cp’’’Co)2(μ,η4:η4-C7H8)] (A) (Cp’’’=1,2,4-tritertbutyl-cyclopentadienyl) towards sandwich complexes containing cyclo-P3, cyclo-P4, and cyclo-P5 ligands under mild conditions is presented. The heterobimetallic triple-decker sandwich complexes [(Cp*Fe)(Cp’’’Co)(μ,η5:η4-P5)] (1) and [(Cp’’’Co)(Cp’’’Ni)(μ,η3:η3-P3)] (3) (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) were synthesized and fully characterized. In solution, these complexes exhibit a unique fluxional behavior, which was investigated by variable temperature NMR spectroscopy. The dynamic processes can be blocked by coordination to {W(CO)5} fragments, leading to the complexes [(Cp*Fe)(Cp’’’Co)(μ3,η5:η4:η1-P5){W(CO)5}] (2 a), [(Cp*Fe)(Cp’’’Co)(μ4,η5:η4:η1:η1-P5){(W(CO)5)2}] (2 b), and [(Cp’’’Co)(Cp’’’Ni)(μ3,η3:η2:η1-P3){W(CO)5}] (4), respectively. The thermolysis of 3 leads to the tetrahedrane complex [(Cp’’’Ni)2(μ,η2:η2-P2)] (5). All compounds were fully characterized using single-crystal X-ray structure analysis, NMR spectroscopy, mass spectrometry, and elemental analysis.