The Synthesis and Characterization of Two-Dimensional Ferromagnetic Extended Structures Containing High-Spin (S = ⁵/₂) and Low-Spin (S = ¹/₂) Iron(III) Bridged by Cyanide Groups

The reaction of [Fe(salen)](+) and {A(3)[Fe(CN)(6)]} (A = NEt(4), K), depending on the countercation A(+) and on the reaction solvent, led to [(NEt(4)){Fe(salen)}(2){Fe(CN)(6)}](n)(), 4, and [{Fe(salen)}(3){Fe(CN)(6)}(MeOH)(2)](n)().3nH(2)O, 5 [NEt(4) = tetraethylammonium cation, salen = N, N'-ethylenebis(salicylideneiminato) dianion], displaying a similar extended 2D structure. Complex 5 crystallizes in the monoclinic, space group P2(1)/n, a = 13.495(7) Å, b = 14.220(9) Å, c = 33.137(5) Å, beta = 96.74(2) degrees, and Z = 4. It assumes a two-dimensional network layer structure consisting of cyclic octanuclear [-Fe(h.s.)-NC-Fe(l.s.)-CN-](4) units with [Fe(salen)(MeOH)(2)](+) located between the interlayer as a countercation. Complex 4 exhibits a metamagnetic behavior with a field-induced transition from an antiferromagnetic to a ferromagnetic-like state and a Neel temperature of ca. 6 K.