Reversible and Irreversible [2+2] Cycloaddition Reactions of Heteroallenes to a Gallaphosphene

[2+2] Cycloaddition reactions of gallaphosphene L(Cl)GaPGaL 1 (L=HC[C(Me)N(2,6-i-Pr2C6H3)](2)) with carbodiimides [C(NR)(2); R=i-Pr, Cy] and isocyanates [RNCO; R=Et, i-Pr, Cy] yielded four-membered metallaheterocycles LGa(Cl)P[mu-C(X)NR]GaL (X=NR, R=i-Pr 2, Cy 3; X=O, R=Et 4, i-Pr 5, Cy 6). Compounds 4-6 reversibly react with CO2 via [2+2] cycloaddition at ambient temperature to the six-membered metallaheterocycles LGa(Cl)P[mu-C(O)O]-mu-C(O)N(R)GaL (R=Et 7, i-Pr 8, Cy 9). Compounds 2-9 were characterized by IR and heteronuclear (H-1, C-13{H-1}, P-31{H-1}) NMR spectroscopy and elemental analysis, while quantum chemical calculations provided a deeper understanding on the energetics of the reactions.

Automated summary

The study involved cycloaddition reactions of gallaphosphene with carbodiimides and isocyanates to synthesize four-membered and six-membered metallaheterocycles, with reversible reactions confirmed. Characterization of the compounds was carried out using IR and heteronuclear NMR spectroscopy, along with elemental analysis, while quantum chemical calculations provided insights into the energetics of the reactions.