Metal-Free Activation of Hydrogen, Carbon Dioxide, and Ammonia by the Open-Shell Singlet Biradicaloid [P(μ-NTer)]2.

The Group 15 open-shell singlet biradicaloid [P(μ-NTer)]2 (Ter=2,6-bis(2,4,6-trimethylphenyl)phenyl) was utilized in the activation of stable small molecules. Fast reactions with H2 , CO2 , and NH3 were observed. Dihydrogen easily added to [P(μ-NTer)]2  , yielding [HP(μ-NTer)]2 under ambient conditions whereas reversible release of molecular hydrogen was observed at slightly elevated temperatures (T>60 °C). As [P(μ-NTer)]2 is a species with phosphorus in the unusual formal oxidation state +II, it is capable of reducing carbon dioxide to afford a zwitterionic compound, [OP(μ-NTer)2 P], and carbon monoxide. The reaction of [P(μ-NTer)]2 with ammonia led to the formation of an azadiphosphiridine after rearrangements of the central P2 N2 heterocycle.