The Cyanurate Ribbon in Structural Coordination Chemistry: An Aggregate Structure That Persists across Different Coordination Environments and Structural Types
journal contributionposted on 1997-12-10, 00:00 authored by Larry R. Falvello, Isabel Pascual, Milagros Tomás, Esteban P. Urriolabeitia
A series of nine coordination compounds is described, in which a common supramolecular structure, a ribbon of cyanurates, persists across variations in the metal center, coordination geometry, coordination environment, and crystal type. The syntheses and solid-state structures, as determined by single-crystal X-ray diffraction, are described for six of the complexes, trans-[Cu(cyan-κN)2(H2O)2]·2Na(cyan)·4H2O (1), trans-[Cu(cyan-κN)2(NH3)2] (5), trans-[Cu(cyan-κN)2(NH3)2]trans-[Cu(cyan-κO2)2(NH3)4] (6), trans-[Ni(cyan-κN)2(NH3)4] (7), (OC-6-33)-[Ni(cyan-κN)2(NH3)2(H2O)2] (8), and [Cu(cyan-κN)(PPh3)2]·2CDCl3 (9). The results are discussed together with the previously reported structures of the other three complexes, [M(cyan-κN)(H2O)5](cyan)·2H2O (M = Mn (2), Co (3), Ni (4)). In all cases, the ribbon of cyanurates is propagated through a recognition interaction involving a pair of hydrogen bonds between adjacent cyanurates, with a topological pattern of the type (8). In eight of the nine cases, the ribbon is linear, but for compound 5, which is the first product of the reaction from which compound 6 is derived, the ribbon is crenelled. An unsuccessful attempt to synthesize a product without the cyanurate ribbon in the solid state is described. The possibility that the cyanurate ribbon represents a traditional self-assembly in some of these systems but not in others is discussed. It is concluded that the formation of the cyanurate ribbon is a determinative factor in the solid-state structural coordination chemistry of the cyanurates of metals of the first transition series.