Guest Exchange Reactions in Isostructural 3D Porous Coordination Polymers of Ni(II), Co(II), and Mn(II)

A series of isostructural compounds, {[Ni-2(DBIBA)(3)]center dot(BF4)Q center dot 6H(2)O}(n) (1), {[Ni-2(DBIBA)(3)]center dot(ClO4)center dot 3H(2)O}(n) (2), {[Ni2(DBIBA)(3)]center dot(NO3)center dot 3H(2)O}(n) (3), {[Ni-2(DBIBA)(3)]center dot Cl center dot C2H5OH}(n) (4) {[Co-2(DBIBA)(3)]center dot(ClO4)center dot 3H(2)O}(n) (5), {[Co-2(DBIBA)(3)]center dot Cl center dot 3C(2)H(5)OH}(n) (7), {[Co-2(DBIBA)(3)]center dot Cl center dot 3DMF}(n) (8), {[Co-2(DBIBA)(3)]center dot Cl center dot 3CH(3)COCH(3)center dot 7H(2)O}(n) (9), and {[Mn-2(DBIBA)(3)]center dot Cl center dot 3DMF center dot 3H(2)O}(n) (10), have been afforded via anion and solvent exchanges of previously reported coordination polymers {[Ni-2(DBIBA)(3)]center dot Cl center dot 18H(2)O}(n), {[Co-2(DBIBA)(3)]center dot Cl center dot 9H(2)O}(n), and {[Mn-2(DBIBA)(3)]center dot Cl center dot 3H(2)O}(n) (DBIBA = 5-di(1H-benzo[d]imidazol-1-yl)benzoate). Anion-exchanged compounds including {[Co-2(DBIBA)(3)]center dot(NO3)center dot 3H(2)O}(n) (6) have also been synthesized under solvothermal conditions by employing metal salts and the corresponding acid hydrolysis of the cyanide functional group of 5-di(1H-benzo[d]imidazol-1-yl) benzonitrile (DBIBN). These structures are obtained with retaining crystallinity, and only insignificant changes are observed in bond lengths and bond angles involving the metal ion. However, noncovalent supramolecular interactions (anion-pi, pi pi, and hydrogen bonding) are utterly affected or changed. Interestingly, in complex 9, the chloride ion moves from the node of the parent complex to the center of the cavity, where it is surrounded by a hexameric water cluster revealing strong H-bonding, which is very rare to be seen. Exchange of solvent molecules leaves the size of the voids unaltered, but anion exchanges are accompanied by shrinking of the voids, except in the case of NO3 exchange, where there is no change in volume. All are isoreticular structures with a binodal 4,6-connected stp net topology. These compounds have been characterized by single-crystal X-ray crystallography, IR spectroscopy, TGA, PXRD, and elemental analysis.