Abstract
Cocrystallization of di(4-fluorobenzenesulfonyl)amine, (4-F-C6H4SO2)2NH (= FAH), with 1,3,3- trimethylurea (TrMU) from dichloromethane/petroleum ether afforded the molecular cocrystal FAH・TrMU (1, monoclinic, P21/n, Z′ = 1) and the salt cocrystal FAH・TrMU・Me2NH2 +・FA− (2, monoclinic, P21, Z′ = 1). The minor product 2 resulted from a hydrolysis reaction of TrMU and was obtained by serendipity. The salt component of 2, Me2NH2 +・FA− (3, monoclinic, C2, Z′ = 6), was prepared by metathesis of [Me2NH2]Cl with Ag[FA] and is not isomorphous to its previously reported congeners Me2NH2 +・(4-X-C6H4SO2)2N− (4 - 7 for X = Cl, Br, I or Me, all monoclinic, Cc, Z′ = 1). The three new structures display one-dimensional arrays (catemers) based upon classical two- or three-centre hydrogen bonds that use N-H or N+-H groups as donors and S=O, C=O or N− groups as acceptors. In 1, the catemers consist of alternating FAH and TrMU molecules, in 3 of alternating Me2NH2 + and FA− ions (six independent formula units), in 2 of alternating Me2NH2 + and FA− ions (one independent unit) and FAH・ ・ ・ TrMU・ ・ ・ heterodimers acting as side-groups to the ionic polymer. The packings of 1 - 3 are completely devoid of short fluorine-oxygen contacts below the van derWaals limit, as are all the known crystal structures containing FAH or FA− entities (“oxophobia” of the C-F groups). The Z′ = 6 structure of 3 may be interpreted as a stratagem to avoid short F・ ・ ・O contacts, in contrast to the Z′ = 1 structures of 4 - 6, which exhibit hydrogen-bonded ion catemers similar to the catemer of 3, and two halogen bonds C-X・ ・ ・O=S per formula unit
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