Structures and CO₂ Reactivity of Zinc Complexes of Bis(diisopropyl‑) and Bis(diphenylphosphino)amines

The bis­(phosphino)­amines (R₂P)­NH­(PR′₂) (R = R′ = isopropyl; R = R′ = phenyl; R = isopropyl, R′ = phenyl) react with ZnEt₂ to form complexes with two different structural motifs, either the homoleptic monomeric P,P-chelates Zn­[N­(<i>i</i>-Pr₂P)₂]₂ and Zn­[N­(<i>i</i>-Pr₂P)­(Ph₂P)]₂ or the heteroleptic dimeric Zn₂N₂P₂ heterocycles {EtZn­[N­(PPh₂)₂]}₂ and {EtZn­[N­(PPh₂)­(<i>i</i>-Pr₂P)]}₂. In two cases, CO₂ reacts with these complexes to give adducts Zn­[O₂CP­(<i>i</i>-Pr₂)­NP­(<i>i</i>-Pr₂)]₂ and Zn­[O₂CP­(<i>i</i>-Pr₂)­NPPh₂]­[Ph₂PN­(<i>i</i>-Pr₂P)]­ZnEt₂, similar to adducts formed from the reaction of CO₂ with frustrated Lewis pairs (FLPs). In the other two cases, reaction with CO₂ results in cleavage and rearrangement of the N–P bonds to give either N­(PPh₂)₃ or Ph₂P­(<i>i</i>Pr₂P)­NPPh₂. The zinc complexes and their CO₂ products were characterized with a combination of single crystal X-ray diffraction and multinuclear NMR spectroscopy