A series of cyanide-bridged chain mixed Fe(III)/Ln(III) (Ln = Pr, Nd, Sm, Eu, Gd, Tb) complexes with the tridentate ligand 2,4,6-tri(2-pyridyl)-1,3,5-triazine (tptz) used as a capping group has been prepared. Reactions of tptz and LnCl3 with K3Fe(CN)6 yield a family of air-stable 1-D compounds {[Pr(tptz)(H2O)4Fe(CN)6]·8H2O}∞ (1), {[Nd(tptz)(H2O)4Fe(CN)6]·8H2O}∞ (2), {[Sm(tptz)(H2O)4Fe(CN)6]·8H2O}∞ (3), {[Eu(tptz)(H2O)4Fe(CN)6]·6H2O}∞ (4), {[Gd(tptz)(H2O)4Fe(CN)6]·6H2O}∞ (5), and {[Tb(tptz)(H2O)4Fe(CN)6]·8H2O}∞ (6). Temperature dependent magnetic susceptibility studies of 1–6 reveal that in 3, the Sm(III) and Fe(III) ions are ferromagnetically coupled with 3-D ordering occurring below 3.5 K. The appearance of the frequency dependent out-of-phase signal is explained in terms of an ordering with a spin glass-like behavior. To compare the magnetic behavior of 3 with related compounds, {[Sm(tptz)(H2O)4Co(CN)6]·8H2O}∞ (7) and {[La(tptz)(DMF)(H2O)3Fe(CN)6]·5H2O}∞ (8), {[Sm(tmphen)(DMF)3(H2O)Fe(CN)6]·2H2O}∞ (9), {[Sm(tmphen)2(H2O)2Fe(CN)6]·MeOH·13H2O}∞ (10) and {[Sm(tmphen)2(H2O)2Cr(CN)6]·MeOH·9H2O}∞ (11) with 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) were also prepared.