Gallaphosphaketene 1b reacts with silylenes either to silaphosphenes (2a/b, 4) or gallaphosphene 3. The nucleophilic character of the P atoms in 3 and 4 is proven in reactions with HCl, BnOH, MeI, MeOTf, and MeLi, respectively, demonstrating the promising potential of heavy π-bonded p-block element compounds for small molecule activation reactions.

Heavy main group element compounds with heteronuclear double bonds are of interest due to their fascinating reactivity. Herein, the synthesis of silaphosphenes L¹Ga(X)PSiL² (X = Cl 2a, Me 2b, L¹ = [N(Dipp)C(Me)]₂CH, Dipp = 2,6- ⁱ Pr₂C₆H₃; L² = PhC(N ^t Bu)₂) and L¹Ga(Cl)PSiL⁴ 4 (L⁴ = [N(Dipp)C(Me)]₂) is reported, which are obtained from reactions of gallaphosphaketenes L¹Ga(X)PCO (X = Cl 1a, Me 1b) with silylenes L²SiCl and the N-heterocyclic silylene L⁴Si, respectively. In contrast, gallaphosphene L¹GaPSi(Cl)L³ 3 (L³ = DippNC(CH₃)CHC(CH₂)NDipp) formed in the reaction of 1a with the β-diketiminate-substituted silylene L³Si. Silaphosphenes 2a and 4 and gallaphosphene 3 are promising reagents for reactions with nucleophiles and electrophiles as is exemplarily demonstrated with HCl, MeI, MeOTf, MeLi, BnOH, BnNC, and CO₂, respectively.