MOLECULAR AND CRYSTAL-STRUCTURE OF THE DIMERIC STRONTIUM BIS[BIS(TRIMETHYLSILYL)AMIDE] AND STRONTIUM BIS[BIS(TRIMETHYLSILYL)AMIDE].2DME

The dimeric strontium bis[bis(trimethylsilyl)amide] 1 crystallizes from toluene in the triclinic space group P1BAR {a = 983,5(6); b = 1238,1(7); c = 2890(2) pm; alpha = 99,65(1)-degrees; beta = 91,67(1)-degrees; gamma = 96,03(2); Z = 3 dimers}. The characteristic moiety of this base-free strontium diamide is the planar, four-membered Sr2N2-ring with SrN-bond lengths of 264 pm and a NSrN-angle of 84-degrees. The bond distance between the strontium and the terminal, planar nitrogen atom is approximately 20 pm shorter. The strontium bis[bis(trimethylsilyl)amide] . 2DME 2 crystallizes in the monoclinic space group C2/c {a = 1333,5(3); b = 1715,0(3); c = 1490,8(3) pm; beta = 93,64(1)-degrees; Z = 4}. This molecule includes the crystallographic C2-symmetry. The six-coordinate strontium shows bond distances to the nitrogen atoms of 254 pm and to the ether oxygen atoms of approximately 265 pm with a NSrN-angle of 136-degrees.