Mixed-ligand MnIIand CuIIcomplexes with alternating 2,2′-bipyrimidine and terephthalate bridges

Abstract

The novel polymeric complexescatena-poly[[diaquamanganese(II)]-μ-2,2′-bipyrimidine-κ4N1,N1′:N3,N3′-[diaquamanganese(II)]-bis(μ-terephthalato-κ2O1:O4)], [Mn2(C8H4O4)2(C8H6N4)(H2O)4]n, (I), andcatena-poly[[[aquacopper(II)]-μ-aqua-μ-hydroxido-μ-terephthalato-κ2O1:O1′-copper(II)-μ-aqua-μ-hydroxido-μ-terephthalato-κ2O1:O1′-[aquacopper(II)]-μ-2,2′-bipyrimidine-κ4N1,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 preparedviaa 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 MnIIcentres in a parallel fashion. In (II), the tpht2−anions act asendo-bridges and connect two CuIIcentres 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 thebaxis. In (I), the MnIIcation 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 CuIIcation is also on a special position (site symmetry \overline{1}). 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 MnIIcation in (I) has a trigonally deformed octahedral geometry, whereas the CuIIcations in (II) are in distorted octahedral environments. The CuIIpolyhedra are inclined relative to each other and share common edges.