Self-assembly, characterisation, and crystal structure of multinuclear metal complexes of the [2X3] and [3X3] grid-type

摘要

The self-assembly of new multimetallic complexes of grid-type architecture is described.The binding of a set of tris-terdentate ligands, 1a-1b, based on terpyridine-like subunits,with different octahedrally coordinated metal ions leads to the formation of species whose structure depends strongly on the ligand, the metal ion, the counterion, the solvent, and the reaction conditions. Under suitable conditions, the [3X3] grid was obtained from the reaction of ligand 1a with zinc tetrafluoroborate and from ligand 1b with mercury triflate. The other ligands led to the formation of mainly one compound of composition [M_6L_5]~(12+),which has the structure of an incomplete [2X3] grid. The crystal structure of such a [2X3] grid, [Co_6(1d)_5]~(12+), has beendetermined.In this complex, the three central pyrimidine-pyridine-pyrimidine non-coordinating sites adopt transoid NC-CN conformations. The muchless stable cisoid conformations, the "pinching" of the coordinationsites in the complex, the weaker donor strength of the central binding site, and the steric demand of the substituents are all factors condtributing to the reluctance to produce the [3X3] structure. A subtle interplay between the nature of the metal, the steric demand of the ligand, the reaction conditions, and the type of counterion determine the product of that by tuning the parameters, complexes containing six or nine octahedrally coordinated metal ions in a well-defined grid-type arrangement are accessible. Both types of arrays, [2X3] and [3X3], are of interest as self-assembled inorganic architectures of well-defined structure and nuclearity that may be suitable prototypes for selective information storage media.