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

Cycloaddition reactions of distibene [L(MeN)GaSb] (L = HC[C(Me)NDipp]; Dipp = 2,6--PrCH)[double bond, length as m-dash] with a series of organoazides RN (R = Ph, -CFPh, 1-adamantyl (ada)) yielded azadistibiranes [L(MeN)GaSb]NR (R = Ph 1, -CFPh 2, ada 3), whereas MeSiN reacted with insertion into one Ga-Sb bond and formation of L(MeN)GaSbSb(NSiMe)Ga(NMe)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(NMe) and formation of tetrastibacyclobutane 7, while the reaction of 5 with a second equivalent of PhN gave heteroleptic azadistibirane 9, which isomerized at elevated temperature to distibene 10. Cycloaddition also occurred in reactions of [L(X)GaSb] (X = NMe, OEt, Cl) with MeSi(H)CN, yielding distibiranes [L(X)GaSb]C(H)SiMe (X = NMe11, 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(MeN)GaSb] with PhN and MeSiN and the electronic nature of the resulting compounds were studied by DFT calculations.