Metal-Ligand Polyhedra
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Metal ions with square planar coordination, when mixed with suitable ligands, can self-assemble into polyhedra of various sizes. Geometrical constraints limit the number of metal ions (vertices) to 6, 12, 24, 30, or 60 for entropically favored regular or semiregular polyhedra[1]. Shown at right () is the "main chain" of a crystallographic model for the largest such structure reported as of May, 2010[2]. form the vertices of a 26-face polyhedron[3]. Three square faces and one triangular face meet at each vertex.
Each palladium ion is coordinated by . The nitrogens are bridged by a ("ligand"). There are two ligand molecules (L) per metal ion (M); hence, this structure is called M24L48.
References and Notes
- ↑ Coxeter, H. S. M., Regular Polytopes, Dover Publications, New York, 3rd ed., 1973.
- ↑ Sun QF, Iwasa J, Ogawa D, Ishido Y, Sato S, Ozeki T, Sei Y, Yamaguchi K, Fujita M. Self-assembled M24L48 polyhedra and their sharp structural switch upon subtle ligand variation. Science. 2010 May 28;328(5982):1144-7. Epub 2010 Apr 29. PMID:20430973 doi:10.1126/science.1188605
- ↑ M24L48 forms a 26-faced rhombicubooctahedron with 18 square faces and 8 triangular faces. In this instance, the rectangular faces are very close to squares 13.35 Ångstroms on a side.
Models
- M24L48 main chain atoms only: Image:M24L48 main chains.pdb
- M24L48 all atoms: Image:M24l48-single-polyhedron.pdb
