SYNTHESIS OF SUBSTITUTED CALCIUM-BIS(DISI LYLAMIDES) BY TRANSMETALATION OF TIN(II) AND TIN(IV) AMIDES

Stannylenes as well as stannanes with substituted disilylamino groups are valuable synthons for the synthesis of alkaline earth metal bis(di silylamides) via the transmetallation reaction. Whereas bis -tetrameth yl-2,5-disilaaza-cyclo-pentyl]stannylene 1 is a suitable reagent for t his type of reaction, hylsilyl-tris(trimethylsilyl)silylamino]stannyle ne 2 (monoclinic, P2(1)/c, a = 1492.6(2), b = 1705.2(2), c = 1865.3(3) pm, beta = 109.03(2)degrees, Z = 4) is not only attacked at the Sn-N- bond but also the N-Si-bond is cleaved by calcium metal. Similar light sensitivity as for 2 is observed for the mercury bis [trimethylsilyl- tris(trimethylsilyl)silylamide] 3, the homolytic M-N-bond cleavage lea ds to the formation of the trimethylsilyl-tris(trimethylsilyl)silylami no radical (g = 2.00485; a(N) = 16.2 G). The calcium tin exchange reac tion of 1 in THF yields ahydrofuran-O)calcium-bis[2,2,5,5-tetramethyl- 2,5- disilaaza-cyclo-pentanide] 4 (monoclinic, P2(1)/n, a = 1060.9(2), b = 1919.3(5), c = 1686.0(3) pm, beta = 90.30(2)degrees, Z = 4). The stannanes Me(n-4)Sn[N(SiMe(3))(2)](n) with n = 1 or 2 are also valuabl e materials for the synthesis of ydrofuran-O)calcium-bis[bis(trimethyl silyl)amide].