A heteronuclear CuIIGdIII complex [CuIILGdIII(NO3)3] with the hexadentate Shiff-base compartmental ligand N,N′-ethylenebis(3-ethoxysalicylaldiimine) (H2L) has been synthesized and structurally characterized. The intermolecular semicoordination of nitrate oxygen to copper(II) results a one-dimensional zigzag chain, which are linked by H-bonding to form a two-dimensional sheet. Magnetic studies reveal ferromagnetic interaction within the dinuclear core and antiferromagnetic interaction propagated through the extended network (Full-size image (<1 K), where H=−2JSCu·SGd+β(gCu·SCu+gGd·SGd)H−zJ′〈S4Z〉S4Z).