A General Pathway to Heterobimetallic Triple‐Decker Complexes. Issue 7 (30th January 2020) - Piesch, Martin
Abstract: A systematic study on the reactivity of the triple‐decker complex [(Cp'''Co)2 (μ, η 4 :η 4 ‐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, η 5 :η 4 ‐P5 )] (1 ) and [(Cp'''Co)(Cp'''Ni)(μ, η 3 :η 3 ‐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, η 5 :η 4 :η 1 ‐P5 ){W(CO)5 }] (2 a ), [(Cp*Fe)(Cp'''Co)(μ4, η 5 :η 4 :η 1 :η 1 ‐P5 ){(W(CO)5 )2 }] (2 b ), and [(Cp'''Co)(Cp'''Ni)(μ3, η 3 :η 2 :η 1 ‐P3 ){W(CO)5 }] (4 ), respectively. The thermolysis of 3 leads to the tetrahedrane complex [(Cp'''Ni)2 (μ, η 2 :η 2 ‐P2 )] (5 ). All compounds were fully characterized using single‐crystal X‐ray structure analysis, NMR spectroscopy, mass spectrometry, and elemental analysis. Abstract : From double to triple : A synthetic route to otherwise inaccessible heterometallic triple‐decker complexes is reported (see scheme). The cobalt complex [(Cp'''Co)2 (toluene)] (Cp'''=1, 2, 4‐tritertbutyl‐cyclopentadienyl) as a source for unsaturated {Cp'''Co} fragments was reacted with the sandwich complexes [Cp*Fe(η 5 ‐P5 )], [Cp'''Co((η 4 ‐P4 )] and [Cp'''Ni(η 3 ‐P3 )] to form novel heterobimetallic triple‐decker complexes.