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Heterotapes: A Persistent, Dual-Synthon Hydrogen-Bonding Motif



The small dinitrile anion carbamoyldicyanomethanide, [C(CN)2-(CONH2)] (cdm), reproducibly forms a hydrogen-bonded tape containing two different supramolecular synthons: a “heterotape”. The tape incorporates both an amide dimer and a nitrile-containing ring. The robustness of the motif is confirmed by its persistence from an isolated tape in a separated ion-pair structure, [K(15c5)2](cdm)⋅ H2O, to its incorporation into coordination complexes of octahedral metals, thus facilitating the formation of 2D sheets. Complexes containing coligands that occupy the equatorial coordination sites, [Cu(2,2′-py2NH)2(cdm)2]⋅ 2MeOH, [Ni(cyclam)(cdm)2], and [Cu(cyclam)(cdm)2]⋅2MeOH (cyclam=1,4,8,11-tetraazacyclotetradecane, 2,2′-py2NH=di(2-pyridyl)amine), show retention of the heterotape motif, whilst the ethylene diamine complex [Cu-(en)2(cdm)2] (en=ethylene diamine) displays an alternative hydrogen-bonding motif due to interference from the diamine ligands.