Liang Zhao

The coordination-driven self-assembly of two metal−carbonyl-cluster-coordinated dipyridyl donors, (4-C₅H₄N)₂C≡CCo₂(CO)₆ (1) and (4-C₅H₄N)₂C≡CMo₂Cp₂(CO)₄ (2), with a linear diplatinum(II) acceptor ligand was investigated. The structures of the resulting self-assembled polygons were found to be controlled by the steric bulk of the metal−carbonyl cluster adduct. The use of a sterically less imposing ligand 1 resulted in a pentagon−hexagon mixture, which was characterized by electrospray ionization time-of-flight mass spectroscopy. The exclusive formation of a [5 + 5] pentagon was achieved by the self-assembly of the bulkier molybdenum donor ligand 2 with a linear organoplatinum(II) acceptor ligand. Molecular force field modeling was used to study the structural details of the pentagonal and hexagonal architectures. The first Fe₃−Co₆−Pt₆ trimetal [3 + 3] hexagon was also synthesized via the combination of 1 with a 120° ferrocenyldiplatinum(II) acceptor.

Two types of supramolecular transformations, wherein a self-assembled Pt(II)-pyridyl metal−organic polygon is controllably converted into an alternative polygon, have been achieved through the reaction between cobalt carbonyl and the acetylene moiety of a dipyridyl donor ligand. A [6 + 6] hexagon is transformed into two [3 + 3] hexagons, and a triangle−square mixture is converted into [2 + 2] rhomboids. ¹H and ³¹P NMR spectra are used to track the transformation process and evaluate the yield of new self-assembled polygons. Such transformed species are identified by electrospray ionization (ESI) mass spectrometry. This new kind of supramolecule-to-supramolecule transformations provides a viable means for constructing, and then converting, new self-assembled polygons.