New yttrium(III) and copper(II) coordination polymers with partially protonated cyclohexane-1,2,3,4,5,6-hexacarboxylato ligands: Synthesis, crystal structures and properties

Two coordination polymers, [Y(H 2 O) 4 (H 3 chhc)]·6H 2 O ( 1 ) and [Cu 5 (H 2 O) 10 (Hchhc) 2 ]·4H 2 O ( 2 ) with H 6 chhc = cyclohexane-1,2,3,4,5,6-hexacarboxylic acid) represent rare examples of metal complexes with partially protonated cyclohexane-1,2,3,4,5,6-hexacarboxylato ligands. The [Y(H 2 O) 4 ] 3+ units in 1 are interlinked by the triprotonated (H 3 chhc) 3− anions in a η 5 μ 4 bridging mode to form 2D (4 3 ) 2 (4 6 ·6 6 ·8 3 ) topological networks, which are stacked along [0 1 0] direction in ···ABAB··· fashion with the lattice H 2 O molecules sandwiched between layers. The pentameric [Cu 5 (H 2 O) 10 ] 10+ units in 2 are bridged by monoprotonated (Hchhc) 5− anions in a η 8 μ 6 fashion to generate a 3D MOF of an unprecendented (4 3 )(4 5 ·6 7 ·8 3 ) topology with the lattice H 2 O molecules in channels. The temperature-dependent magnetic susceptibility data of 2 could be modeled to a combination of a linear chain of equally-spaced Cu(II) ions ( J 1 = 1.86 cm −1 ) with an isosceles triangular Cu 3 unit ( J 2 = 5.86 cm −1 ).