Template Effects of Lithium Salts on the Crystallization of Diazasulfates: X-ray Structures of {THF.Li(2)[O(2)S(N(t)Bu)(2)]}(8).2LiOH.2LiCl and {(THF.Li)(2)[O(2)S(N(t)Bu)(2)].(THF)LiCl}(2).
The addition of 2 equiv of (n)BuLi to solutions of O(2)S[N(H)R](2) (R = (i)Pr, (t)Bu) produces the dilithium diazasulfates {Li(2)[O(2)S(N(i)Pr)(2)]}(n)() (2) and {THF.Li(2)[O(2)S(N(t)Bu)(2)]}(n)() (3), which were characterized by solid-state (7)Li and (13)C NMR spectroscopy. Crystals were obtained from a THF/n-hexane solution of 3 and determined by X-ray crystallography to be {THF.Li(2)[O(2)S(N(t)Bu)(2)]}(8).2LiOH.2LiCl (4), which consists of a 64-atom (Li(20)S(8)N(16)O(18)Cl(2)) cluster composed of two Li(4)O(4) cubes and a central Li(4)O(4) step-shaped ladder. The eight [O(2)S(N(t)Bu)(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)[O(2)S(N(t)Bu)(2)].(THF)LiCl}(2) (5). The structure of 5 incorporates an 18-atom (Li(6)S(2)N(4)O(4)Cl(2)) quinary cluster in which two {[THF.Li(&mgr;-O)(&mgr;-N(t)Bu)](2)S} molecules are held together by two (THF.LiCl) units. The mean Li-Cl distance (2.348 Å) linking the {[THF.Li(&mgr;-O)(&mgr;-N(t)Bu)](2)S} molecules to the (THF.LiCl) units is significantly shorter than the corresponding value of 2.483 Å within these units. Crystal data: 4, monoclinic, P2(1)/n, a = 18.557(1) Å, b = 15.731(1) Å, c = 28.063(2) Å, beta = 107.381(1) degrees, V = 7817.9(9) Å(3), and Z = 2; 5, monoclinic, P2(1)/n, a = 11.583(3) Å, b = 17.126(5) Å, c = 13.891(4) Å, beta = 94.613(4) degrees, V = 2747(1) Å(3), and Z = 2.
Brask
Justin K.
JK
Departments of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4, and University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
Chivers
Tristram
T
Yap
Glenn P. A.
GP