Construction of Metal−Organic Oxides from Molybdophosphonate Clusters and Copper-Bipyrimidine Building Blocks

Abstract

A series of organic-inorganic hybrid materials of the copper(II)-molybdophosphonate family have been prepared using conventional hydrothermal conditions. The reactions of MoO(3), copper(II) acetate, bipyrimidine (bpyr), a phosphonic acid, and water at temperatures below 160 degrees C and in the presence of a mineralizer such as acetic acid or HF provided crystalline samples of materials of the general class {Cu(2)(bpyr)}(4+)/Mo(x)O(y)-phosphonate. The recurrent themes of the structures are the presence of the binuclear {Cu(2)(bpyr)}(4+) and pentanuclear {Mo(5)O(15)(O(3)PR)(2)}(4-) building blocks. For the alkylphosphonate-containing materials, [{Cu(2)(bpyr)(2)}Mo(5)O(15)(O(3)PCH(3))(2)].2.5H(2)O (1.2.5H(2)O) is two-dimensional and exhibits {Cu(bpyr)}(n)(2n+) chains, while [{Cu(2)(bpyr)(H(2)O)}Mo(5)O(15)(O(3)PCH(2)CH(3))(2)] (2) is three-dimensional. The diphosphonate series of materials {{Cu(2)(bpyr)}(4+)[Mo(5)O(15){O(3)P(CH(2))(n)PO(3)}](4-) with n = 2-6 (4, 5, 7-9) in all cases contain the characteristic [Mo(5)O(15){O(3)P(CH(2))(n)PO(3)}](n)(2n+) chains, linked through {Cu(2)(bpyr)}(4+) rods into three-dimensional frameworks. When n = 1, the three-dimensional phase [{Cu(2)(bpyr)}MoO(2)(HO(3)PCH(2)PO(3))(2)].2H(2)O (3.2H(2)O) is obtained, the exclusive example of a structure constructed from isolated {MoO(6)} polyhedra rather than pentamolybdate clusters. The Ni(II)-containing phase [{Ni(2)(bpyr)(H(2)O)(4)}Mo(5)O(15){O(3)P(CH(2))(3)PO(3)}].9H(2)O (6.9H(2)O) was also prepared and compared to the structure of the Cu(II) analogue, [{Cu(2)(bpyr)(H(2)O)(4)}Mo(5)O(15){O(3)P(CH(2))(3)PO(3)}].3H(2)O (5.3H(2)O). Magnetic susceptibility studies of the compounds revealed that the magnetic behavior was consistent in all cases with antiferromagnetically coupled dimers. However, the magnitude of the exchange coupling was clearly dependent on the orientation of the M(II) mean equatorial or basal planes relative to the bipyrimidine plane. Thus, when the metal and bipyrimidine planes are nearly coplanar, the J values are in the -77 to -87 cm(-1) range, while J values of -2 to -5 cm(-1) are observed for the compounds with out-of-plane orientations.

Metal-organodiphosphonates: Structural consequences of introducing aromatic tethering groups. The structures of [Cu(phen){HO3P(C12H8)PO3H}], [{Cu(phen)}2{HO3P(C12H8)PO3H}] and [Cu(terpy){HO3P(C12H8)PO3H}] and of the bimetallic materials [{Cu(LL)}2MoO2{HO3P(C12H8)PO3H}3] (LL=2,2-bipyridine, o-phenanthroline)

“…The water molecule is hydrogen bound to the O10 sites of the pendant phosphonate groups. The most unusual feature of the structures of 4 and 5 is the absence of the nearly ubiquitous {Mo 5 O 15 (O 3 PR) 2 } 4À cluster that appears in both molecular and polymeric structures of oxomolybdates with organophosphonate ligands [33]. This observation supports our previous studies that suggest that the organic tether in diphosphonate structures serves not only as a simple spacer but as a structural determinant whose steric and electronic properties contribute intimately to the overall structure.…”

“…Three-dimensional ''pillared layers" and other threedimensional frameworks are the rule for these materials, although the detailed connectivities within the Cu-P-O inorganic layers may exhibit considerable variability. The structural chemistry of copper-organodiphosphonates can be expanded by introducing nitrogen-donor coligands [27][28][29][30][31][32] or by exploiting the copperdiphosphonate moiety in the construction of bimetallic oxide hybrid materials [33][34][35][36][37][38]. Encouraged by the often unique structural chemistry of the parent copper-aromatic-diphosphonates, we have begun to study the chemistry of the Cu/ligand/(aromatic diphosphonate) and Cu/ligand/Mo x O y /(aromatic diphosphonate) systems (where ligand = 2,2-bipyridine (bpy), o-phenanthroline (phen) and 2,2 0 :6;2 00 -terpyridine (terpy)).…”

Hydrothermal synthesis and structural characterization of an organically-templated open-framework trimolybdates

“…It has been demonstrated that the hydrothermal chemistry of polyoxomolybdates involves many interrelated reaction variables, including the pH, the molybdenum source, and the identities of other reaction species, the temperature, and time (Wu et al, 2002;Xu et al, 2000;Zhang et al, 2007;Zhang et al, 2015;Hubbard et al, 2008). Molybdophosphonates as building blocks or subunits in extended structures have been studied (Hubbard et al, 2008;Armatas et al, 2008;Jones et al, 2010;Armatas et al, 2009). A molybdenum diphosphonate network structure exhibiting reversible dehydration and selective uptake of methanol have also been reported and it is the first molybdenum diphosphonates in the absence of coligands (Ayi et al, 2013).…”

Coordination of the carboxylate of the functionalized Strandberg anion in a three dimensional covalence framework

“…Generally, in constructing organic-inorganic hybrids based on [(RPO 3 ) 2 Mo 5 O 15 ] 4− polyoxoanion, the pending R group in the organophosphonate derivatives [(RPO 3 ) 2 Mo 5 O 15 ] 4− does not participate in coordination to the transition metal center [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]20]. However, when R = −R'PO 3 the R group may take part in coordination to other M atoms, forming polyoxoanion chain in Zubieta's materials [22][23][24][25][26][27][28][29][30][31][32]. The presence of terminal carboxylate groups on each side of the polyanion [(HO 2 CCH 2 PO 3 ) 2 Mo 5 O 15 ] 4− renders this species highly attractive for the further decoration with organic molecules or coordination to metal ions and for construction of multidimensional structure.…”