Mixed-ligand MnII and CuII complexes with alternating 2,2'-bipyrimidine and terephthalate bridges

摘要

The novel polymeric complexes catena-poly[[diaquamanganese(II)]-μ-2,2'-bipyrimidine-κ4 N1,N1':N3,N3'-[diaquamanganese(II)]-bis(μ-terephthalato-κ2 O1:O4)], [Mn2(C8H4O4)2(C8H6N4)(H2O)4] n , (I), and catena-poly[[[aquacopper(II)]-μ-aqua-μ-hydroxido-μ-terephthalato-κ2 O1:O1'-copper(II)-μ-aqua-μ-hydroxido-μ-terephthalato-κ2 O1:O1'-[aquacopper(II)]-μ-2,2'-bipyrimidine-κ4 N1,N1':N3,N3'] tetrahydrate], {[Cu3(C8H4O4)2(OH)2(C8H6N4)(H2O)4]·4H2O}n , (II), containing bridging 2,2'-bipyrimidine (bpym) ligands coordinated as bis-chelates, have been prepared via a ligand-exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht2-) anions were found. In (I), two tpht2- anions acting as bis-monodentate ligands bridge the MnII centres in a parallel fashion. In (II), the tpht2- anions act as endo-bridges and connect two CuII centres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn2(tpht)2(bpym)(H2O)4] entity in (I) and the trinuclear [Cu3(tpht)2(OH)2(bpym)(H2O)4]·4H2O coordination entity in (II) build up one-dimensional polymeric chains along the b axis. In (I), the MnII cation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central CuII cation is also on a special position (site symmetry ). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face-to-face π-π interactions [in (I)], forming three-dimensional metal-organic frameworks. The MnII cation in (I) has a trigonally deformed octahedral geometry, whereas the CuII cations in (II) are in distorted octahedral environments. The CuII polyhedra are inclined relative to each other and share common edges.