Synthesis of distibiranes and azadistibiranes by cycloaddition reactions of distibenes with diazomethanes and azides

Abstract

Cycloaddition reactions of distibene [L(Me₂N)GaSb]₂ (L = HC[C(Me)NDipp]₂; Dipp = 2,6-i-Pr₂C₆H₃) with a series of organoazides RN₃ (R = Ph, p-CF₃Ph, 1-adamantyl (ada)) yielded azadistibiranes [L(Me₂N)GaSb]₂NR (R = Ph 1, p-CF₃Ph 2, ada 3), whereas Me₃SiN₃ reacted with insertion into one Ga–Sb bond and formation of L(Me₂N)GaSbSb(NSiMe₃)Ga(NMe₂)L (4). Analogous compounds 5 and 6 formed after heating of 1 and 2 above 60 °C. Prolonged heating of 5 resulted in a [2 + 2] cycloaddition accompanied by elimination of LGa(NMe₂)₂ and formation of tetrastibacyclobutane 7, while the reaction of 5 with a second equivalent of PhN₃ gave heteroleptic azadistibirane 9, which isomerized at elevated temperature to distibene 10. Cycloaddition also occurred in reactions of [L(X)GaSb]₂ (X = NMe₂, OEt, Cl) with Me₃Si(H)CN₂, yielding distibiranes [L(X)GaSb]₂C(H)SiMe₃ (X = NMe₂11, OEt 12, Cl 13). Compounds 1–13 were characterized by IR, UV-Vis and NMR spectroscopy and sc-XRD. The mechanism of the reaction of [L(Me₂N)GaSb]₂ with PhN₃ and Me₃SiN₃ and the electronic nature of the resulting compounds were studied by DFT calculations.