Acyclic sulfur-nitrogen compounds. Syntheses and crystal and molecular structures of bis((trifluoromethyl)sulfonyl)amine ((CF3SO2)(2)NH), magnesium hexaaquo bis((trifluoromethyl)sulfonyl)amide dihydrate ([Mg(H2O)(6)][(CF3SO2)(2)N](2)center dot 2H(2)O), and bis(bis(fluorosulfonyl)amino)sulfur ((FSO2)(2)NSN(SO2F)(2))

The syntheses of three acyclic (fluorosulfonyl)- or ((trifluoromethyl)sulfonyl)-nitrogen derivatives and their crystal and molecular structures are reported. The structures of bis((trifluoromethyl)sulfonyl)amine (1; (CF3SO2)(2)NH) and the corresponding anion in magnesium hexaaquo bis((trifluoromethyl)sulfonyl)amide dihydrate (2; [Mg(H2O)(6)][(CF3SO2)(2)N](2) . 2H(2O)) shed some light on the observed high gas-phase acidity of (CF3SO2)(2)NH. Extensive electron delocalization in the anion [(CF3SO)(2)N](-) from planar, sp(2)-hybridized nitrogen into 3d orbitals of sulfur results in a noticeable shortening of the S-N bond on deprotonation. Similar electron delocalization is observed for the third compound, bis(bis(fluorosulfonyl)amino)sulfur (3; (FSO2)(2)NSN(SO2F)(2)), which features planar nitrogens with nearly six equidistant S-N bonds and extremely short S-O and S-F bonds. Compounds 2 and 3 have not been reported previously. Their unexpected, accidental formation and their characterization will be discussed. Compound 1 crystallizes in the space group Peen (No. 56) with a = 16.404(3) Angstrom, b = 5.535(1) Angstrom, c = 9.557(2) Angstrom, and Z = 4. Compound 2 crystallizes in the space group P2(1)/n (No. 14) with a = 6.400(1) Angstrom, b = 14.300(1) Angstrom, c = 14.421(1) Angstrom, beta = 97.45(1)degrees, and Z = 2, Compound 3 crystallizes in the space group P2(1)/c (No. 14) with a = 12.762(1) Angstrom, b = 6.744(1) Angstrom, c = 13.627(1) Angstrom, beta = 91.42(1)degrees, and Z = 4.