Synthesis, Structure, and Magnetic Properties of Heterometallic Dicyanamide-Bridged Cu−Na and Cu−Gd One-Dimensional Polymers

The monometallic precursors L1Cu and L2Cu (L1H2 standing for 1,3-bis((3-ethoxysalicylidene)amino) propane and
L2H2 standing for 1,2-bis((3-methoxysalicylidene)amino) ethane) react with sodium dicyanamide (dca) (NaN3C2), a
mixture of gadolinium nitrate, and sodium dicyanamide to yield heterodinuclear L2CuNa(NCNCN) and L1CuGd(NO3)(NCNCN)2 entities. The structural determination shows that two Cu−Na entities are linked by dca with an
original μ1,1 coordination mode, evidenced here for the first time, to yield tetranuclear complexes. Two hydrogen
bonds operate between the water molecule coordinated to one of the sodium ions and the free nitrogen atoms of
two dca ligands, yielding infinite zigzag chains. The structural determination of the Cu−Gd entities indicates that
they are held together by two dca ligands, bridging alternately Cu to Gd and Gd to Gd cations, in the more
common μ1,5 mode to yield a one-dimensional (1D) network. The dca ligands are not able to transmit interaction
between the magnetically active centers in these chains, which are the unique example of structurally characterized
Cu−Gd complexes involving dca ligands.