Mixed‐ligand MnII and CuII complexes with alternating 2,2′‐bipyrimidine and terephthalate bridges

The novel polymeric complexes catena‐polydiaquamanganese(II)]‐μ‐2,2′‐bipyrimidine‐κ⁴N¹,N^1′:N³,N^3′‐diaquamanganese(II)]‐bis(μ‐terephthalato‐κ²O¹:O⁴)], Mn₂(C₈H₄O₄)₂(C₈H₆N₄)(H₂O)₄]_n, (I), and catena‐polyaquacopper(II)]‐μ‐aqua‐μ‐hydroxido‐μ‐terephthalato‐κ²O¹:O^1′‐copper(II)‐μ‐aqua‐μ‐hydroxido‐μ‐terephthalato‐κ²O¹:O^1′‐aquacopper(II)]‐μ‐2,2′‐bipyrimidine‐κ⁴N¹,N^1′:N³,N^3′] 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 (tpht^2?) anions were found. In (I), two tpht^2? anions acting as bis‐monodentate ligands bridge the Mn^II centres in a parallel fashion. In (II), the tpht^2? anions act as endo‐bridges and connect two Cu^II 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 Mn^II 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 Cu^II 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 Mn^II cation in (I) has a trigonally deformed octahedral geometry, whereas the Cu^II cations in (II) are in distorted octahedral environments. The Cu^II polyhedra are inclined relative to each other and share common edges.