Template effects of lithium salts on the crystallization of diazasulfates:: X-ray structures of {THF•Li2[O2S(NtBu)2]}8•2LiOH•2LiCl and {(THF•Li)2[O2S(NtBu)2]•(THF)LiCl}2

The addition of 2 equiv of (BuLi)-Bu-n to solutions of O2S[N(H)R](2) (R = Pr-i,Bu-t) produces the dilithium diazasulfates {Li-2[O2S((NPr)-Pr-i)(2)]}(n) (2) and {THF.Li-2[O2S((NBu)-Bu-t)(2)]}(n) (3), which were characterized by solid-state Li-7 and C-13 NMR spectroscopy. Crystals were obtained from a THF/n-hexane solution of 3 and determined by X-ray crystallography to be {THF.Li-2[O2S((NBu)-Bu-t)(2)]}(8).2LiOH.2LiCl (4), which consists of a 64-atom (Li20S8N16O18Cl2) cluster composed of two Li4O4 cubes and a central Li4O4 step-shaped ladder. The eight [O2S((NBu)-Bu-t)(2)](2-) dianions in 4 exhibit three distinct modes of bonding to the Li+ cations: (a) bis-(N,O),(N', O')-chelate, (b) N,O-chelate, bis-N',O'-monodentate, and (c) bis-(N, O),(N,N')-chelate, O'-monodentate. The synthesis of 3 in the presence of 1 equiv of LiCl produces the dimer {(THF.Li)(2)[O2S((NBu)-Bu-t)(2)].(THF)LiCl}(2) (5). The structure of 5 incorporates an 18-atom (Li6S2N4O4Cl2) quinary cluster in which two {[THF.Li(mu-O)(mu-O)(mu-(NBu)-Bu-t)](2)S} molecules are held together by two (THF.LiCl) units. The mean Li-Cl distance (2.348 Angstrom) linking the {[THF.Li(mu-O)(mu-O)(u-(NBu)-Bu-t)](2)S} molecules to the (THF.LiCl) units is significantly shorter than the corresponding value of 2.483 Angstrom within these units. Crystal data: 4, monoclinic, P2(1)/n, a = 18.557(1) Angstrom, b = 15.731(1) Angstrom, c = 28.063(2) Angstrom, beta = 107.381(1)degrees, V = 7817.9(9) Angstrom(3), and Z = 2; 5, monoclinic, P2(1)/n, a = 11.583(3) Angstrom, b = 17.126(5) Angstrom, c = 13.891(4) Angstrom, beta = 94.613(4)degrees, V = 2747(1) Angstrom(3), and Z = 2.