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RESEARCH PRODUCT

Synthesis, structure and properties of new heterometallic octanuclear Li2Na2Cu4 and decanuclear Li2Zn8 complexes

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Abstract A carboxylate containing polydentate ligand in combination with exogeneous succinate (suc) has been used to stabilize heterometallic octanuclear [Li2Na2Cu4(cpdp)2(suc)2(CH3OH)2(H2O)4]Cl2·6H2O (1) and decanuclear Na(H3O)2[Li2Zn8(cpdp)4(suc)2(H2O)4]Cl2Br3·6MeOH·19H2O (2) complexes. The reaction of ligand H3cpdp (H3cpdp = N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol) with stoichiometric amounts of CuCl2/sodium succinate, and ZnCl2/sodium succinate, allowed isolation of complexes 1 and 2, respectively. Analyses of single crystal X-ray structures indicate that complex 1 is capped by two [Cu2(cpdp)]+ molecular building units and two succinate linkers, while complex 2 is overlaid by four [Zn2(cpdp)]+ molecular building units and two succinate linkers. Whereas complex 1 shows monodentate terminal and tridentate μ3:η2:η1:η1 bridging coordination of carboxylate, and μ4:η2:η1:η1:η1 bridging mode of succinate, complex 2 displays monodentate terminal and anti-anti μ2:η1:η1 bidentate bridging coordination of carboxylate, and μ4:η1:η1:η1:η1 bridging mode of succinate. To our knowledge, 1 is the first example of copper/lithium/sodium-based hetero-octanuclear complex with any class of bridging or non-bridging ligand showing three different binding modes of carboxylates. Again, 2 is also the first example of a hetero-decanuclear metallomacrocyclic complex with any class of bridging or non-bridging ligand combining both lithium and zinc. Variable temperature magnetic investigation of 1 discloses sensible antiferromagnetic interactions intermediated among the copper centers. Thermal behavior of 1 and 2 has been examined by thermogravimetric analysis indicating that the complexes are stable up to ∼430 °C.