Methylene-bridged calixarenes have emerged as excellent ligands for polynuclear cluster formation. In this contribution methylene- and oxa-bridged calixarenes have been examined as candidates for cluster formation with cobalt(II) nitrate, affording two markedly different structures. The nature of the structures is highly dependent on the bridging atoms. Reaction of p-tert-butylcalixarene with cobalt(II) nitrate in DMF results in the formation of a coordination polymer in which the calixarene adopts a 'double-partial' cone conformation. A similar reaction with p-tert- butyltetrahomodioxacalixarene affords a discrete complex in which a central heteroatom also coordinates to the metal centre, with the calixarene in a 'double-cone' conformation. The synthesis and structure of both compounds is presented.
- Coordination chemistry
- Coordination polymer