A General Pathway to Heterobimetallic Triple-Decker Complexes

Chemistry. 2020 Feb 3;26(7):1518-1524. doi: 10.1002/chem.201905240. Epub 2020 Jan 30.

Abstract

A systematic study on the reactivity of the triple-decker complex [(Cp'''Co)2 (μ,η44 -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,η54 -P5 )] (1) and [(Cp'''Co)(Cp'''Ni)(μ,η33 -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)(μ3541 -P5 ){W(CO)5 }] (2 a), [(Cp*Fe)(Cp'''Co)(μ45411 -P5 ){(W(CO)5 )2 }] (2 b), and [(Cp'''Co)(Cp'''Ni)(μ3321 -P3 ){W(CO)5 }] (4), respectively. The thermolysis of 3 leads to the tetrahedrane complex [(Cp'''Ni)2 (μ,η22 -P2 )] (5). All compounds were fully characterized using single-crystal X-ray structure analysis, NMR spectroscopy, mass spectrometry, and elemental analysis.

Keywords: cobalt; cyclo-Pn ligands; iron; nickel; triple-decker complexes.