The First Coordination Polymers and Hydrogen Bonded Networks Containing Octahedral Nb6 Clusters and Alkaline Earth Metal Complexes

Three novel coordination polymers built of octahedral niobium cyanochloride clusters [Nb6Cl12(CN)6] and alkaline earth metal complexes have been prepared by reaction of aqueous solutions of (Me4N)4Nb6Cl18 and KCN with solutions of alkaline earth metal salts and 1,10-phenanthroline (phen) (1:2 molar ratio) in H2O/EtOH. The structures of [Ca(phen)2(H2O)3]2[Nb6Cl12(CN)6]·(phen)(EtOH)1.6 (1), [Ca(phen)2(H2O)2]2[Nb6Cl12(CN)6]·(phen)2·4H2O (2), and [Ba(phen)2(H2O)]2[Nb6Cl12(CN)6] (3) were determined by single-crystal X-ray diffraction. The three compounds were found to crystallize in the monoclinic system (space group Pn) with a = 11.5499(6) (angstrom), b = 17.5305(8) (angstrom), c = 21.784(1) (angstrom), (beta)= 100.877(1)° for 1; triclinic system (P1) with a = 12.609(4) (angstrom), b = 13.262(4) (angstrom), c = 16.645(5) (angstrom), (alpha)= 69.933(6)°, (beta)= 64.380(1)°, (gamma)= 67.803(1)° for 3. Compounds 1 and 2 are built of cluster anions [Nb6Cl12(CN)6]4- trans-coordinated by two Ca2+ complexes via CN ligands to form neutral macromolecular units [Ca(phen)2(H2O)3]2[Nb6Cl12(CN)6] in 1 and [Ca(phen)2(H2O)2]2[Nb6Cl12(CN)6] in 2. Water of coordination and cyanide ligands form hydrogen bonded 3D and 2D frameworks for 1 and 2, respectively. The structure of 3 consists of [Nb6Cl12(CN)6]4- cluster anions and [Ba(phen)2(H2O)]2+ complexes linked through bridging cyanide ligands to form a neutral three-dimensional framework in which each barium complex is bound to three neighboring Nb6 clusters and each Nb6 cluster is linked to six Ba complexes.