Ligand influences on copper molybdate networks:: The structures and magnetism of [Cu(3,4′-bpy)MoO4], [Cu(3,3′-bpy)0.5MoO4], and [Cu(4,4′-bpy)0.5MoO4]•1.5H2O

The reactions of a Cu(II) salt, MoO3, and the appropriate bipyridine ligand yield a series of bimetallic oxides, [Cu(3,4'-bpy)MoO4] (1), [Cu(3,3'-bpy)(0.5)MoO4] (2), and [Cu(4,4'-bpy)(0.5)MoO4](.)1.5H(2)O (3(.)1.5H(2)O). The structures of 1-3 exhibit three-dimensional covalent frameworks, constructed from bimetallic oxide layers tethered by the dipodal organoimine ligands, However, the {CuMoO4} networks are quite distinct, For structure 1, the layer consists of corner-sharing {MoO4} tetrehedra and {CuN2O3} square pyramids, while the layer of 2 is constructed from (MoO4} tetrehedra and binuclear {Cu2O6N2} units of edge-sharing copper square pyramids. The oxide substructure of 3 consists of {MoO4} tetrahedra corner-sharing with tetranuclear clusters of edge-sharing {CuO5N} octahedra. Crystal data: C10H8N2O4CuMo (1), orthorhombic Pbca, a = 12.4823(6) Angstrom, b = 9.1699(4) Angstrom, c = 19,5647(9) Angstrom, V = 2239.4(l) Angstrom(3), Z = 8; C5H4NO4CuMo (2), triclinic P1(-), a = 5.439(l) Angstrom, b = 6.814(1) Angstrom, c = 10.727(2) Angstrom, alpha = 73.909(4)degrees, beta = 78.839(4)degrees; gamma = 70.389(4)degrees; V = 357.6(l) Angstrom(3), Z = 2; C(10)H(8)N(2)O(8)Cu(2)Mo(2)(.)3H(2)O 3(.)1.5H(2)O, triclinic P1(-), a = 7.4273(7) Angstrom, b = 9.2314(8) Angstrom, c = 13.880(1) Angstrom, alpha 71.411(2)degrees, beta = 88.528(2)degrees, gamma = 73.650(2)degrees, V = 863.4(1) Angstrom(3), Z = 2. The magnetic properties of 1-3 arise solely from the presence of the Cu(II) sites, but reflect the structural differences within the bimetallic oxide layers. Compound 1 exhibits magnetic behavior consistent with ferromagnetic chains which couple antiferromagnetically at low temperature, Compound 2 exhibits strong antiferromagnetic dimeric interactions, with the magnetic susceptibility data consistent with the Bleaney-Bowers equation. Similarly, the magnetic susceptibility of 3 is dominated by antiferromagnetic interactions, which may be modeled as a linear S = 1/2 Heisenberg tetramer.