Structural Rearrangement in Cyclic Cu(II) Pyridyltriazole Complexes: Oxidation of Dabco to Oxalate and CO Conversion to Carbonate.

Structural rearrangements in metal-organic supramolecules constructed from the coordination of Cu(II) with -xpt (-xylylenebis(pyridyltriazole)) are investigated upon their interaction with 1,4-diazabicyclo[2.2.2]octane (dabco) and carbon dioxide-enriched air. The binuclear [Cu(-xpt)] complexes react with dabco to produce a carbonate-bridged trinuclear complex, [Cu(-xpt)(µ-CO)], and an oxalate-bridged binuclear complex, [Cu(-xpt)(µ-CO)], where carbonate and oxalate likely originate from CO and dabco, respectively. The trinuclear complex reassembles the original dimer upon the removal of the carbonate ion. Similarly, polymeric [Cu(-xpt)(PF)], formed from Cu(I) and -xpt (-xylylenebis(pyridyltriazole)) coordination, undergoes oxidation in CO-enriched air to yield a tetranuclear Cu(II) complex, Cu(-xpt)(μ-CO)(μ-OH)(μ-OCOCH). The reaction progress is monitored by UV-Vis spectroscopy, and the major products are characterized by single-crystal X-ray diffraction.