Formation of 1D and 3D Coordination Polymers in the Solid State Induced by Mechanochemical and Annealing Treatments: Bis(3-cyano-pentane-2,4-dionato) Metal Complexes

Bis(3-cyano-pentane-2,4-dionato) (CNacac) metal complex. [M(CNacac)2]. which acts as both a metal-ion-like and a ligand-like building unit. forms supramolecular structures by self-assembly. Co-grinding of the metal acetates of Mn-II, Co-II, Ni-II, Cu-II and Zn-II with CNacacH formed a CNacac complex ill all cases: mononuclear complex Was formed in the cases of Mn-II, Cu-II and Zn-II, whereas polymeric ones were formed in the cases of Fe-II, Coll and Ni-II. Subsequent annealing converted the mononuclear complexes of Mn-II, Cu-II and Zn-II to their corresponding polymers as a result of dehydration of the mononuclear complexes. The resultant Mn-II, Fe-II, Co-II, N-II and Zn-II polymeric complexes had a common 3D structure With high thermal Stability. In the case of Cu-II, a 1D polymer was obtained. The Mn-II, Cu-II and Zn-II polymeric complexes returned to their original mononuclear complexes on exposure to water vapour but they reverted to the polymeric complexes by re-annealing. Co-grinding of metal chlorides with CNacacH and annealing of the mononuclear CNacac complexes prepared from solution reactions Were also examined for comparison. [Mn(CNacac)(2)(H2O)(2)], [M(CNacac)(2)(H2O)(2)(H2O)] (M = Cu-II and Zn-II) and [M(CNacac)(2)] (M=Mn-II, Fe-II and Zn-II) are new compounds which clearly indicated the power of the combined mechanochemical/annealing method for the synthesis of varied metal coordination complexes.