Transformation of the cyclo-P₅ Middle Deck in [(Cp*Fe)(Cp'''Co)(μ,η⁵ :η⁴ -P₅ )] upon Functionalization - A...

The heterobimetallic triple-decker complex [(Cp*Fe)(Cp'''Co)(μ,η⁵  : η⁴ -P₅ )] (1) was functionalized by main group nucleophiles and subsequently electrophilically quenched or oxidized. Reacting 1 with group 14 nucleophiles revealed different organo-substituted P₅ R middle-decks depending on the steric and electronic effects of the used alkali metal organyls (2: R=tBu; 3: R=Me). Further, with group 15 nucleophiles, the first structural characterized monosubstituted complexes with phosphanides could be obtained as P₅ ligands containing exocyclic {PR₂ } units (4: R=Cy, H; 5: R=Ph). These monoanionic complexes 2-5 were isolated and subsequent electrophilic quenching revealed novel types of neutral functionalized polyphosphorus complexes. These complexes bear formal chains of P₅ R'R'' (6: R'=tBu, R'=Me) in a 1,3-disubstitution pattern or P₆ R'R''R''' units (7: R'=Cy, R''=H, R'''=Me; 8: R'=Me, R''=Ph, R'''=Me) in a 1,1,3-substitution as middle-decks stabilized by one {Cp'''Co} and one {Cp*Fe} fragment. One-electron oxidation of 2, 3 or 5 by AgBF₄ gave access to paramagnetic triple-decker complexes bearing P₅ R middle-decks in various coordination fashions (R=tBu (10), R=PPh₂ (12)). Interestingly, for R=Me (11), a dimerization is observed revealing a diamagnetic tetranuclear cluster containing a unique dihydrofulvalene-type P₁₀ R₂ ligand. All complexes were characterized by crystallographic and spectroscopic methods (EPR, multinuclear NMR and mass spectrometry) and their electronic structures were elucidated by DFT calculations.