The magnetic measurements of polymeric complexes [L . Cu(hfac)(2)](n), (L = pyrimidine, 4-methylpyrimidine, and quinazoline) revealed the presence of ferromagnetic interactions among the copper spins. The X-ray crystal-structure analysis of the pyrimidine and quinazoline complexes showed a copper-ligand alternating chain. The ferromagnetic transition of the quinazoline complex was observed at about 0.12 K. Pyrimidine(2)-Cu(ClO4)(2) complex was found to be a ferromagnet with a transition temperature of about 10 K.