New μ-hydroxido-bridged copper nitrate dimer and μ4-oxido-bridged copper phenylacetate quasi-tetrahedron: Direct synthesis and uphill conversion

Dinuclear [Cu2(μ-OH)] fragment and its self-assembled tetranuclear part [Cu2(μ4-O)Cu2] are found in two copper(II) complexes of ligand H3bpmp: [Cu2(μ2-OH)(μ-H2bpmp)(μ1,3-NO3)][Cu2(μ2-OH)(μ-H2bpmp)(NO3)(H2O)](NO3)2·2H2O (1·2H2O) and [Cu4(μ4-O)(μ-H2bpmp)2(μ1,3-O2CCH2Ph)4] (2) [H3bpmp = 2,6-bis-[(3-hydroxy-propylimino)-methyl]-4-methylphenol]. These complexes have been synthesized and characterized by single crystal X-ray crystallography. Complex 1 showed unique reactivity with phenylacetate anions to provide 2 in which two [Cu2(μ2-OH)] units available within same crystal lattice collapsed to give [Cu4(μ4-O)] hub. Formation of the [Cu4] compound is also achieved from individual components and phenylacetate ligands, which allows an effective tuning of the self-assembly of two ligand bound [Cu2] fragments and removal of H+ from hydroxido bridges to provide oxido nucleus.

Selective coordination of four ancillary ligands PhCH2CO2− in a complementary fasion dictate the self-assembly process of phenoxido ligand bound four CuII ions around a central oxido group. Hydroxido to oxido bridge conversion is fulfilled during ligand exchange reaction by PhCH2CO2− groups.Figure optionsDownload as PowerPoint slide