Synthesis, Crystal Structure, and Magnetic Properties of a Ferrimagnetic Layered Compound [NEt₄][Mn(5-Cl-salen)]₂[Fe(CN)₆] (NEt₄ = Tetraethylammonium, 5-Cl-salen = N,N′-Ethylenebis((5-chlorosalicylidene)aminato))

The discrete trinuclear complex [(NEt₄){Mn(H₂O)(5-Cl-salen)}₂{Fe(CN) ₆}]·H₂O, 3, and a two-dimensional heterometal assembly [(NEt₄){Mn(5-Cl-salen)}₂{Fe(CN)₆}]_n, 4, have been prepared (NEt₄ = tetraethylammonium, 5-Cl-salen = N,N′-ethylenebis(5-chlorosalicylidene)aminato) dianion). Compound 4 crystallizes in the monoclinic space group P2₁/c with cell dimensions of a = 13.104(3) Å, b = 12.861(3) Å, c = 15.526(2) Å, β = 105.98(1)°, Z = 2 and is isostructural to the previously synthesized metamagnetic compound, [K{Mn(3-MeOsalen}₂{Fe-(CN)₆}·2DMF]_n, 5. The structure assumes a two-dimensional network consisting of the cyclic tetramer (-Mn-NC-Fe-CN-)₄ as a net unit [with dimensions of Fe-Cl = 1.947(8) Å, Fe-C2 = 1.951(8) Å, Mn-N1 = 2.286(7) Å, Mn-N2 = 2.266(7) Å, Mn-N-C = 154.4(7)°, Mn-N-C = 146.1(7)°]. The magnetic study (magnetic susceptibility vs T, field-cooled magnetization and zero-field cooled magnetization vs T, hysteresis loop and saturation magnetization vs H up to 55 kOe) shows that the compound is a metamagnet with ferrimagnetic layers and antiferromagnetic interlayer interactions, and with a Neel temperature T_N = 4.0 K. The distinctly different magnetic properties of 4 and 5 are discussed and correlated with the structural parameters. The magnetic behavior of 3 was represented by the fitting parameters: g_Mn = 1-98, g_Fe = 2.01, J = +5.9 cm^-1, D = -6.4 cm^-1, zJ′ = -0.38 cm^-1 on the basis of a trinuclear spin system (S_Mn hs, S_Fe, S_Mn hs) = (2, 1/2, 2) and includes a zero-field splitting term D and an intermolecular interaction term zJ′ within the molecular field approach. The dehydration reaction of 3 in the solid state also leads to 4.