Self-Assembly of Neutral Platinum-Based Supramolecular Ensembles Incorporating Oxocarbon Dianions and Oxalate

Five neutral platinum-based macrocycles incorporating cyclic oxocarbondianions, squarate and croconate and their
acyclic analogue, oxalate, have been synthesized in 90−95% yield via self-assembly. The combination of the
diplatinum molecular clip with all three dianions afforded molecular rectangles, whereas a platinum-based 60°
acceptor unit produced a supramolecular rhomboid with croconate ion but a triangle with squarate ion. In all cases,
multinuclear NMR spectra were consistent with the formation of single highly symmetrical species. The three
rectanglular and the rhomboid assemblies were characterized by single-crystal X-ray crystallography. The triangular
species was characterized by FAB mass spectrometry.