Syntheses and Structures of 5-Membered Heterocycles Featuring 1,2-Diphospha-1,3-Butadiene and Its Radical Anion

LGa(P2OC)cAAC 2 features a 1,2-diphospha1,3-butadiene unit with a delocalized p-type HOMO and a p*-type LUMO according to DFT calculations. [LGa(P2OC)cAAC][K(DB-18-c-6)] 3[K(DB-18-c-6] containing the 1,2-diphospha-1,3-butadiene radical anion 3* was isolated from the reaction of 2 with KC8 and dibenzo-18-crown-6. 3 reacted with [Fc][B(C6F5)(4)] (Fc= ferrocenium) to 2 and with TEMPO to [L-HGa-(P2OC)cAAC][K(DB-18-c-6)] 4[K(DB-18-c-6] containing the 1,2-diphospha-1,3-butadiene anion 4-. The solid state structures of 2, 3K(DB-18-c-6], and 4[K(DB-18-c-6] were determined by single crystal X-ray diffraction (sc-XRD).

Automated summary

Based on DFT calculations, LGa(P2OC)cAAC 2 possesses a delocalized p-type HOMO and p*-type LUMO due to the presence of a 1,2-diphospha-1,3-butadiene moiety. Reaction of 2 with KC8 and dibenzo-18-crown-6 led to the isolation of [LGa(P2OC)cAAC][K(DB-18-c-6)] 3[K(DB-18-c-6] containing the 1,2-diphospha-1,3-butadiene radical anion 3*. Further reactions of 3 with [Fc][B(C6F5)(4)] and TEMPO yielded 2 and [L-HGa-(P2OC)cAAC][K(DB-18-c-6)] 4[K(DB-18-c-6] respectively, with the latter containing the 1,2-diphospha-1,3-butadiene anion 4-. The structures of 2, 3[K(DB-18-c-6], and 4[K(DB-18-c-6] were determined using single crystal X-ray diffraction (sc-XRD).