Abstract
The reactivity of the cyclo-P(4) ligand complex [Cp'''Co(η(4)-P(4))] (1) (Cp''' = 1,2,4-tri-tert-butyl-cyclopentadienyl) towards reduction and main group nucleophiles was investigated. By using K[CpFe(CO)(2)], a selective reduction to the dianionic complex [(Cp'''Co)(2)(μ,η(3):η(3)-P(8))](2-) (2) was achieved. The reaction of 1 with (t) BuLi and LiCH(2)SiMe(3) as carbon-based nucleophiles yielded [Cp'''Co(η(3)-P(4)R)](-) (R = (t) Bu (4), CH(2)SiMe(3) (7)), which, depending on the reaction conditions, undergo subsequent reactions with another equivalent of 1 to form [(Cp'''Co)(2)(μ,η(3):η(3)-P(8)R)](-) (R = (t) Bu (5), CH(2)SiMe(3) (8)). In the case of 4, a different pathway was observed, namely a dimerisation followed by a fragmentation into [Cp'''Co(η(3)-P(5) (t) Bu(2))](-) (6) and [Cp'''Co(η(3)-P(3))](-) (3). With OH(-) as an oxygen-based nucleophile, the synthesis of [Cp'''Co(η(3)-P(4)(O)H)](-) (9) was achieved. All compounds were characterized by X-ray crystal structure analysis, NMR spectroscopy and mass spectrometry. Their electronic structures and reaction behavior were elucidated by DFT calculations.