Solid state coordination chemistry: One-, two-, and three-dimensional materials constructed from molybdophosphonate subunits linked through binuclear copper tetra-2-pyridylpyrazine groups

The hydrothermal reactions of MoO3, an appropriate Cu(II) source, tetra-2-pyridylpyrazine (tpypyz), and phosphoric acid and/or an organophosphonate yielded a series of organic-inorganic hybrid materials of the copper-molybdophosphonate family. A common feature of the structures is the entrainment within the extended architectures of chemically robust {Mo 5O15(O3PR)2}4- clusters as molecular building blocks. The cluster is a characteristic feature of the one-dimensional materials [{Cu2(tpypyz)(H2O) 3}Mo5O15(HPO4)(O3PCH 2CO2H)]·H2O (1·H2O) and [{Cu2(tpypyz)-(H2O)}Mo5O 15(O3PC6H5)2]· 2H2O (2·2H2O), the two-dimensional network [{Cu2(tpypyz)(H2O)3}Mo5O 15(HPO4)2]·2H2O (5·2H2O) and the three-dimensional frameworks [{Cu 2(tpypyz)(H2O)2}Mo5O 15{O3P(CH2)nPO3}]· xH2O [n = 3, x = 2.25 (6·2.25H2O); n = 4, x = 0.33 (7·0.33H2O)]. In the case of methylenediphosphonate as the phosphorus component, the unique chelating nature of the ligand precludes formation of the pentamolybdate core, resulting in the chain structures [{Cu2(tpypyz)(H2O)}Mo3O8 (HO 3PCH2PO3)2]·8H2O (3·8H2O) and [{Cu2(tpypyz)(H2O)} 2(Mo3O8)2(O3PCH 2PO3)3]·16.9H2O (4·16.9H2O). For structures 1-7, the secondary metal-ligand building block is the binuclear {Cu2(tpypyz)(H2O) x}4+ cluster. There is considerable structural versatility as a result of the variability in the number of attachment sites at the phosphomolybdate clusters, the coordination geometry of the Cu(II), which may be four-, five-, or six-coordinate, the extent of aqua ligation, and the participation of phosphate oxygen atoms as well as molybdate oxo groups in bonding to the copper sites. Crystal data: 1·H2O, C 26H28N6Cu2Mo5O 28P2, monoclinic C2/c, a = 42.497(2) Å, b = 10.7421(4) Å, c = 20.5617(8) Å, β = 117.178(1)°, V = 8350.1(5) Å3, Z = 8; 2·2H2O, C 36H32N6Cu2Mo5O 24P2, monoclinic P21/c, a = 11.2478(7) Å, b = 19.513(1) Å, c = 21.063(1) Å, β = 93.608(1)°, V = 4613.7(5) Å3, Z = 4; 3·8H2O, C 26H40N6Cu2Mo3O 29P4, monoclinic C2/c, a = 32.580(2) Å, b = 17.8676(9) Å, c = 15.9612(8) Å, β = 104.430(1)°, V = 8993.3(8) Å3, z = 8; 4·16.9H2O, C 51 H71.75Cu4Mo6N12O 21P6, monoclinic P21/c, a = 27.929(3) Å, b = 12.892(2) Å, c = 22.763(3) Å, β = 90.367(2)°, V = 8195.7(2) Å3, Z = 4; 5·2H2O, C 24H28N6Cu2Mo5O 28P2, monoclinic P21/n, a = 11.3222(4) Å, b = 18.7673(7) Å, c = 19.4124(7) Å, β = 98.819(1)°, V = 4076.1(3) Å3, Z = 4; 6·2.25H2O, C 27H28.5N6Cu2Mo5O 24.25P2, monoclinic C2/c, a = 12.8366(5) Å, b = 18.4221(8) Å, c = 34.326(1) Å, β = 100.546(1)°, V = 7980.1(6) Å3, Z = 8; 7·1/3H2O, C 28H28.7N6Cu2Mo5O 23.3P2, monoclinic C2/c, a = 12.577(1) Å, b = 18.336(1) Å, c = 36.476(3) Å, β = 91.929(2)°, V = 8407.3 Å3, Z = 8.