Supramolecular Interactions of Group VI Metal Carbonyl Complexes: The Facilitating Role of 1,3-Bis(p‑isocyanophenyl)urea

An investigation of supramolecular phenomena involving zerovalent transition metal complexes was facilitated by the production of the ditopic isocyanide ligand 1,3-bis­(p-isocyanophenyl)­urea, which was synthesized via substoichiometric phosgenation of 4-isocyanophenylamine and used to coordinate group VI metal carbonyl fragments. The resulting binuclear organometallic complexes were observed to pack into ladder-like anisotropic arrays in the solid state. Crystallographic and computational evidence suggests that this packing motif can be attributed to a combination of intermolecular π–π and urea−π interactions. Similar to other N,N′-diarylureas bearing electron-withdrawing groups, 1,3-bis­(p-isocyanophenyl)­urea and the organometallic complexes prepared therefrom also exhibit an affinity toward anion binding in nonaqueous solution. Equilibrium constants (K) for the formation of host–guest complexes between the organometallic derivatives of 1,3-bis­(p-isocyanophenyl)­urea and chloride, nitrate, and acetate anions exceed 10³, 10⁴, and 10⁵ M^–1, respectively.