A General Pathway to Heterobimetallic Triple-Decker Complexes.

A systematic study on the reactivity of the triple-decker complex [(Cp'''Co)2 (μ,η4 :η4 -C7 H8 )] (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.