Crystal structures and magnetic properties of two new phosphate-metal complexes: [Cu2(bpy)2(μ,η2-HPO4)(μ, η1-H2PO4)(μ,η2-H2PO4)]n and [Cu4(phen)4(μ3,η2-HPO4)2(μ,η2-H2PO4)2(H2PO4)2](H2O)4

Two novel dinuclear-based polynuclear and tetranuclear Cu(II) compounds with mixed HxPO4(3-x)- bridges (x = 1, 2), [Cu2(bpy)2(μ,η2-HPO4)(μ,η1-H2PO4)(μ,η2-H2PO4)]n (1) and [Cu4(phen)4(μ3,η2-HPO4)2(μ,η2-H2PO4)2(H2PO4)2](H2O)4 (2) (in which bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline) have been synthesized and characterized structurally and magnetically. Both Cu(II) ions in a dimeric unit in 1 are in a distorted square pyramidal environment and linked by μ,η2-HPO4 and μ,η1-H2PO4 ligands. Complex 1 is a dinuclear-based polymeric Cu(II) derivative of [Cu2(bpy)2(μ,η2-HPO4)(μ,η1-H2PO4)(μ,η2-H2PO4)] units linked by μ,η2-H2PO4 ligand. Consequently, the Cu(II) ions are alternatively doubly-bridged and singly-bridged along the polymeric chain. In case of 2, each Cu(II) ion displays a distorted square-pyramidal geometry, with two μ3,η2-HPO4 groups and two μ,η2-H2PO4 groups bridging, and two non-bridging H2PO4 groups, involving four copper atoms in a rather unique variety of coordination modes.The magnetic susceptibility measurements reveal a weak antiferromagnetic interaction for both compounds. Magneto-structural trends are discussed, along with their EPR and electronic reflectance spectra and compared with those of related complexes.

Graphical abstractTwo novel dinuclear-based polynuclear and tetranuclear Cu(II) compounds with mixed HxPO4(3-x)- bridges (x = 1, 2), [Cu2(bpy)2(μ,η2-HPO4)(μ,η1-H2PO4)(μ,η2-H2PO4)]n (1) and [Cu4(phen)4(μ3,η2-HPO4)2(μ,η2-H2PO4)2(H2PO4)2](H2O)4 (2) have been synthesized and characterized as well as the magnetic properties discussed. Both Cu(II) ions in a dimeric unit in 1 are in a distorted square pyramidal environment and linked by μ,η2-HPO4 and μ,η1-H2PO4 ligands. In case of 2, each Cu(II) ion displays a distorted square-pyramidal geometry, with two μ3,η2-HPO4 groups and two μ,η2-H2PO4 groups bridging, and two non-bridging H2PO4 groups.Figure optionsDownload full-size imageDownload as PowerPoint slide