Mn^II Coordination Polymers Based on Bi‑, Tri‑, and Tetranuclear and Polymeric Chain Building Units: Crystal Structures and Magnetic Properties

Five new MnII coordination polymers, namely [Mn2(tbip)2(bix)] (1), [Mn3(tbip)3(bix)2] (2), [Mn3(tbip)2(Htbip)2(bib)2]·4H2O (3), [Mn4(tbip)4(bbp)2(H2O)2] (4), and [Mn4(tbip)4(bip)]·2H2O (5), were prepared by hydrothermal reactions of Mn­(II) acetate with H2tbip (5-tert-butyl isophthalic acid) in the presence of different di-imidazolyl coligands (bix =1,4-bis­(imidazol-1-ylmethyl)­benzene, bib =1,4-bis­(imidazol) butane, bbp =1,3-bis­(benzimidazol)­propane, bip =1,3-bis­(imidazol)­propane). All complexes were characterized by elemental analysis, IR spectra, thermogravimetric analysis, single-crystal X-ray crystallography, and powder X-ray diffraction. Single crystal X-ray studies show that these coordination polymers contain homometallic clusters varying from dimeric, trimeric, and tetrameric motifs to polymeric chains depending upon the coligands used. Complex 1 has a 3D 6-connected polycatenane network with dinuclear [Mn2O2] secondary building units. Complex 2 possesses a 3D 8-connected structure with trinuclear [Mn3(COO)6] units. Complex 3 shows a 3D pcu net based on trinuclear [Mn3(COO)6] clusters as nodes. Complex 4 features a 3D 8-connected structure constructed from the distorted square-grid tetranuclear [Mn4(μ2-COO)8(μ2-H2O)] units. Complex 5 shows a 3D (4,5,6)-connected net containing 1D μ-O/μ-COO alternately bridged chains. Magnetic susceptibility measurements indicate that complexes 1 and 3–5 show weak antiferromagnetic interactions between the adjacent MnII ions, whereas 2 is a three-spin center homometallic ferromagnetic system.