Transformation of the cyclo‐P₅ Middle Deck in [(Cp*Fe)(Cp’’’Co)(μ,η⁵:η⁴‐P₅)] upon Functionalization – A Comprehensive Study of Reactivity

Abstract

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 P5R 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 P5R'R’’ (6: R’=tBu, R’=Me) in a 1,3‐disubstitution pattern or P6R'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 P5R 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 P10R2 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.