An unusual 3D-topology and dominant ferromagnetic couplings in two Cu(II)-azide coordination polymers

The coordination polymers [(Cu(N-3)(2))(2)Cu(N-3)(2)(methylpyrazine)(2)](n) 1 and [Cu(4-bromopyridine)(N-3)(2)](n) 2, were prepared from NaN3, Cu(NO3)(2)center dot 3H(2)O and nitrogen-containing heterocycles. 1 contains a three- and four-connected 3D (4.10(2))(2)(4(2).10(4))-dmd-net based on tetrahedral and trigonal planar nodes, whereas 2 is a sheet-structure formed by a uninodal three-connected 8(2).4 2D-net with additional Br center dot center dot center dot Br (mean 3.903(2) angstrom) and Br center dot center dot center dot N(azide) (3.035(5) angstrom) contacts. Both compounds contain end-on-type azide bridges, and 2 has in addition one end-to-end bridge as well. The corresponding magnetic interactions are J(1,2) = +14.9(6) cm(-1) for the end-on azido interactions in 1 with an additional -1.7 cm(-1) coupling through the pyrazine, and J(1) = 36(6) cm(-1) for the end-on azido interactions and J(2) = 2.5(1) cm(-1) for the orthogonal end-to-end azido interactions found in 2.