Preparation of an organometallic molecular square by self-assembly of phosphorus-containing building blocks

Molecular squares are among the most common supramolecular architectures, but phospha-organometallic complexes have not been used as building blocks for this type of structure. Herein we describe the formation of the molecular square [Au{Co(P2C2tBu2)2}]4 (1) by the self-assembly of anionic 1,3-diphosphacyclobutadiene cobalt complexes and gold(I) cations. The X-ray crystallographic determination of the molecular structure of 1 is complemented by solid-state (31)P and (13)C NMR investigations. High-level DFT calculations confirm the assignment of the (31)P and (13)C NMR resonances.