Polynuclear Co(II) and Cu(II) complexes of tetraacetylethane: CuII2(dpa)2(tae)(O2CCF3)2, {[CuII2(dpa)2(tae)(4,4'-bipy)](O2CCF3)2}n, and [CoII2(dpa)4(tae)](O2CCH3)2(H2O)2, dpa = 2,2'-dipyridylamine, tae = tetraacetylethane dianion
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abstract
The syntheses and structures of copper(II) and cobalt(II) complexes employing tetraacetylethane as the bridging ligand have been investigated. The reaction of Cu(O2CCF3)2 with tetraacetylethane (tae) and 2,2'-dipyridylamine (dpa) yielded a dinuclear complex CuII2(dpa)2(tae)(O2CCF3)2 (1), which has an extended hydrogen-bonded chain structure in the solid state. The reaction of 4,4'-dipyridyl (4,4'-bipy) with compound 1 resulted in the formation of a polymeric compound {[CuII2(dpa)2(tae)(4,4'-bipy)](O2CCF3)2}n (2), where the dinuclear unit is cross-linked by the 4,4'-dipyridyl ligand. The reaction of Co(O2CCH3)2 with tetraacetylethane and 2,2'-dipyridylamine yielded a helical dinuclear complex [CoII2(dpa)4(tae)](O2CCH3)2(H2O)2 (3), which forms a hydrogen-bonded band architecture in the solid state. The three-dimensional structure of 3 has molecular sieve-like channels that host methanol molecules reversibly. While only either negligible or weak magnetic exchanges appear to be present in compounds 1 and 2, there appears to be a significant ferromagnetic exchange in 3, which is likely caused by orbital orthogonality of the Co(II) ions, as supported by the crystal structure and EHMO calculations.Key words: cobalt, copper, polynuclear, tetraacetylethane complex, magnetism.
