Inclusion of unique four-clawed crown-like nitrate-water cluster [(NO3)6(H2O)6]6- anions into the inter-spaces of a 3D H-bonded cationic net formed by a cationic calix[4]arene

Reaction of 5,11,17,23-tetramino-25,26,27,28-tetrahydroxy-calix[4]arene (1) with MeI and NaOAc center dot 3H(2)O in DMF produced a tetracationic calix[4]arene [H4L]I-4 (2) {H4L = [5,11,17,23-tetrakis (trimethylammonium)-25,26,27,28-tetrahydroxycalix[4]arene]} in 90% yield. Anion exchange of 2 with [Ag(MeCN)(4)](PF6) in MeCN afforded [H4L](PF6)(4) (3). Treatment of 3 with Na2CO3 or NaNO3 in MeCN afforded two mono-deprotonated complexes [H3L](PF6)(3)center dot MeCN (4.MeCN) and [(H3L)(2){(NO3)(6)(H2O)(6)}]center dot 4MeCN (5.4MeCN). Compounds 4.MeCN and 5.4MeCN have been characterized by elemental analysis, IR spectra, H-1 NMR, and single-crystal X-ray crystallography. 4.MeCN contains a 3D cationic H-bonded [H3L](n)(3n+) net in which PF6- anions are embedded into its 1D channels. 5.4MeCN consists of another 3D cationic H-bonded [H3L](n)(3n+) net in which the unique four-clawed crown-like nitrate-water cluster [(NO3)(6)(H2O)(6)](6-) anions are included into the inter-spaces between the layers of [H3L](3+) trications. The formation of this nitrate-water cluster anion may demonstrate interesting information about the hydration of nitrate in water-related systems.