Tetraaza analogues of lithium and sodium alums: Synthesis and X-ray structures of the single strand polymer [Li(THF)(2){Al[SO2((NBu)-Bu-t)(2)](2)}](infinity) and the contact ion pairs [Na(15-crown-5)][Al{SO2((NBu)-Bu-t)(2)}(2)] and {[Na(15-crown-5)][O2S(mu-NBn)(2)Al(mu-NBnSO2NBn)]}(2)

The reaction of an alkali metal aluminohydride MAlH4 (M = Li, Na) with N,N- bis-(tert-butyl)sulfamide or N,N'-bis-(benzyl)sulfamide in THF produces the complex ions {Al[SO2(NR)(2)](2)}(-) (R = Bu-t, Bn). The X-ray structures o f [Li(THF)(2){Al[SO2((NBu)-Bu-t)(2)](2)}](infinity) (1), [Na(15-crown-5)][A l{SO2((NBu)-Bu-t)(2)}(2)], (2) and {[Na(15-crown-5)][O2S(mu -NBn)(2)Al(mu - NBnSO2NBn)]}(2) (3.3THF) are reported. The two diazasulfate ligands [SO2((N Bu)-Bu-t)(2)](2-) are N,N' chelated to Al3+ in both 1 and 2. In the lithium derivative 1 the spirocyclic {Al[SO2((NBu)-Bu-t)(2)](2)}(-) anions are bri dged by the bis-solvated cations Li(THF)(2)+ to give a polymeric strand. In the sodium salt 2 the complex anion is O,O' chelated to Na+, which is furt her encapsulated by a 15-crown-5 ligand to give a monomeric ion-pair comple x. By contrast, the benzyl derivative 3 forms a dimer in which the terminal [SO2(NBn)(2)](2-) ligands are (N,N'),(O,O') bis-chelated to Al3+ and Na+, respectively, and the bridging ligands adopt a novel N,O-chelate, N'-monode ntate bonding mode. The central core of 3 consists of two four-membered AlO SN rings bridged by two (NBu)-Bu-t groups. Crystal data: 1, orthorhombic, P na2(1), a = 20.159(5)degrees, b = 10.354(3)degrees, c = 15.833(4)degrees, a lpha = beta = gamma = 90 degrees, V = 3304.7(15) Angstrom (3), Z = 4; 2, mo noclinic, P2(1)/n, a = 16.031(2) Angstrom, b = 9.907(2) Angstrom, c = 23.96 3(4) Angstrom, beta = 103.326(2)degrees, Z = 4; 3, triclinic, P (1) over ba r, a = 12.7237(11) Angstrom, b = 14.0108(13) Angstrom, c = 16.2050(14) Angs trom, alpha = 110.351(2)degrees, beta = 111.538(2)degrees, gamma = 97.350(2 )degrees, Z = 1.