Cyanide-bridged bimetallic assemblies [Ni(pn)(2)](2)[Fe(CN)(6)]X . catnH(2)O (X = ClO4- and n = 2 (1); X = BF4- and n = 2 (2); X = PF6- and n = 2 (3)) and [Ni(1,1-dmen)(2)](2)[Fe(CN)(6)]X . nH(2)O (X = ClO4- and n = 2 (4); x = BF4- and n = 3 (5); X = PF6- and n = 2 (6); X = CF3SO3- and n = 2 (7); X = BzO(-) and n = 6 (8); X = I- and n = 4 (9); X = N-3(-) and n = 4 (10); X = NCS- and n = 1 (11); X = NO3- and n = 4 (12)) have been prepared (pn = 1,2-propanediamine, 1,1-dmen = 1,1-dimethylethylenediamine). 7 crystallizes in a monoclinic space group P2(1)/m (no. 11), with a = 10.300(6), b = 20.632(4), c = 10.352(7) Angstrom, beta = 109.45(4)degrees, V = 2074(1) Angstrom(3) for Z = 4. 8 crystallizes in a triclinic space group P (1) over bar (no. 2), a = 10.413(6), b = 22.060(6), c = 10.377(3) Angstrom, alpha = 101.78(2), beta = 95.71(4), gamma = 77.29(3)degrees, V = 2272(1) Angstrom(3) for Z = 2. 10 crystallizes in triclinic space group P (1) over bar (no. 2), a = 10.314(1), b = 10.374(1), c = 10.233(1) Angstrom, alpha = 93.23(1), beta = 106.15(1), gamma = 86.37(1)degrees, V = 1045.0(2) Angstrom(3) for Z = 2. In each compounds [Fe(CN)(6)](3-) coordinates to four [Ni(1,1-dmen)(2)](2+) cations through four cyano nitrogens on a plane, providing a 2-D sheet of a square structure extended by Fe-CN-Ni linkages. The square with four Fe(III) ions at the corners and four trans Ni(II) on the edges shows a slight distortion to a rhombus. A ferromagnetic interaction operates within the sheet in all the compounds. The overall magnetic property is governed by the intersheet separation : a small intersheet separation provides metamagnets (1, 2, 3, 4, 6, 11) owing to intersheet antiferromagnetic interaction, whereas a large intersheet separation (>10 Angstrom) provides ferromagnets (5, 7, 8, 9, 10, 12). The ferromagnets became metamagnets on dehydration owing to shortening of the intersheet separation.