Cyanide-Bridged Fe^III−Mn^III Bimetallic Complexes with Dimeric and Chain Structures Constructed from a Newly Made <i>mer</i>-Fe Tricyanide: Structures and Magnetic Properties

Four cyanide-linked FeIII−MnIII complexes were prepared by reacting Mn Schiff bases with a new molecular precursor (PPh4)[Fe(qcq)(CN)3] [1; qcq = 8-(2-quinolinecarboxamido)quinoline anion]. They include a dimeric molecule, [Fe(qcq)(CN)3][Mn(3-MeOsalen)(H2O)]·2H2O [2·2H2O; 3-MeOsalen = N,N′-ethylenebis(3-methoxysalicylideneiminato) dianion], and three 1D zigzag chains, [Fe(qcq)(CN)3][Mn(5-Clsalen)]·3H2O [3·2MeOH; 5-Clsalen = N,N′-ethylenebis(5-chlorosalicylideneiminato) dianion], [Fe(qcq)(CN)3][Mn(5-Brsalen)]·2MeOH [4·2MeOH; 5-Brsalen = N,N′-ethylenebis(5-bromosalicylideneiminato) dianion], and Fe(qcq)(CN)3][Mn(salen)]·MeCN·H2O [5·MeCN; salen = N,N′-ethylenebis(salicylideneiminato) dianion]. The complexes consist of extensive hydrogen bonding and π−π stacking interactions, generating multidimensional structures. Magnetic studies demonstrate that antiferromagnetic couplings are operative between FeIII and MnIII centers bridged by cyanide ligands. On the basis of an infinite chain model, magnetic coupling parameters of 2−5 range from −9.3 to −14.1 cm−1. A long-range order is observed at 2.3 K for 3 and 2.2 K for 4, while compound 5 shows spin glass behavior possibly coupled with magnetic ordering.