Synthesis and structure of the two-dimensional bimetallic oxide [H4tphz]3[{Zn2(tphz)(H2O)4}{Mo5O15(O3PCH2CH2PO3)}4] • 14H2O:: the hydrothermal conversion of tetra-2-pyridylpyrazine to tetrapyrido [2,3-a:3′,2′-c:2",3"-h:3"′,2"′-j]phenazine (tphz)

The hydrothermal reaction of (NH4)(6)Mo7O24.4H(2)O, ZnSO4.7H(2)O, tetra-2-pyridylpyrazine, ethylenediphosphonic acid, H2O and HF at 170 degreesC for 96 h yields yellow crystals of [H(4)tphz](3)[{Zn-2(tphz)(H2O)(4)} {Mo5O15(O3PCH2CH2PO3)}(4)].14H(2)O (1.14H(2)O) (tphz = tetrapyrido[2,3-a:3',2'-c:2",13"-h:3"',2"' j]phenazine (tphz)). The structure of 1 consists of two-dimensional networks constructed from chains of {Mo5O15(O3PR)(2)}(4-) clusters tethered through the ethylene bridges of the diphosphonate ligands, which are in turn crosslinked through the {Zn-2(tphz)(H2O)(4)}(4divided by) subunits. This connectivity generates intralamellar cavities which are occupied by the tetraprotonated H(4)tphz(4divided by) cations. A curious feature of the chemistry is the hydrothermal conversion of the tetra-2-pyridylpyrazine starting material to tphz. (C) 2003 Elsevier B.V. All rights reserved.