Reversible and Irreversible [2+2] Cycloaddition Reactions of Heteroallenes to a Gallaphosphene
Mahendra K. Sharma, Christoph Wölper, Gebhard Haberhauer, Stephan Schulz
Abstract
Abstract [2+2] Cycloaddition reactions of gallaphosphene L(Cl)GaPGaL 1 (L=HC[C(Me)N(2,6‐i‐Pr 2 C 6 H 3 )] 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[μ‐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 CO 2 via [2+2] cycloaddition at ambient temperature to the six‐membered metallaheterocycles LGa(Cl)P[μ‐C(O)O]‐μ‐C(O)N(R)GaL (R=Et 7 , i‐Pr 8 , Cy 9 ). Compounds 2 – 9 were characterized by IR and heteronuclear ( 1 H, 13 C{ 1 H}, 31 P{ 1 H}) NMR spectroscopy and elemental analysis, while quantum chemical calculations provided a deeper understanding on the energetics of the reactions.