A General Pathway for the Synthesis of Gallastibenes containing Ga=Sb Double Bonds

Reactions of three equivalents of LGa {L=HC[C(Me)N(2,6-iPr₂ C₆ H₃ )]₂ } with SbX₃ (X=F, Cl, Br, I) proceed with insertion into the Sb-X bond, elimination of LGaX₂ , and formation of LGaSbGa(X)L (X=F 1, Cl 2, Br 3, I 4) containing a Ga=Sb double bond. In contrast, the 2:1 molar ratio reaction of LGa and SbCl₃ initially gives the twofold insertion product [L(Cl)Ga]₂ SbCl 7, which could not be isolated due to its strong tendency toward elimination of LGaCl₂ and formation of distibene [L(Cl)GaSb]₂ 5 at 25 °C or cyclotristibine [L(Cl)GaSb]₃ 6 at 8 °C. The formation of 1-6 can be rationalized by formation of the Ga-substituted stibinidene L(X)GaSb as reaction intermediate.