Chiral Cyanide-Bridged CrIII–MnIII Heterobimetallic Chains Based on [(Tp)Cr(CN)3]−: Synthesis, Structures, and Magnetic Properties

By the reactions of MnIII Schiff-base complexes with the tricyanometalate building block, [(Tp)­Cr­(CN)3]− (Tp = Tris­(pyrazolyl) hydroborate), two couples of enantiomerically pure chiral cyano-bridged heterobimetallic one-dimensional (1D) chain complexes, [Mn­((R,R)-Salcy)­Cr­(Tp)­(CN)3·1/4H2O·1/2CH2Cl2]n (1) and [Mn­((S,S)-Salcy)­Cr­(Tp)­(CN)3·1/4H2O·1/2CH2Cl2]n (2) (Salcy = N,N′-(1,2-cyclohexanediylethylene)­bis­(salicylideneiminato) dianion), [Mn­((R,R)-Salphen)­Cr­(Tp)­(CN)3]n (3) and [Mn­((S,S)-Salphen)­Cr­(Tp)­(CN)3]n (4) (Salphen = N,N′-1,2-diphenylethylene-bis­(salicylideneiminato) dianion), have been successfully synthesized. Circular dichroism (CD) spectra confirm the enantiomeric nature of the optically active complexes. Structural analyses reveal the formation of neutral cyano-bridged zigzag single chains in 1 and 2, and neutral cyano-bridged zigzag double chains in 3 and 4. Magnetic studies show that antiferromagnetic couplings are operative between CrIII and MnIII centers bridged by cyanide. Complexes 1 and 2 are the rare examples of chiral ferrimagnets; while complexes 3 and 4 exhibit a coexistence of chirality and spin-glass behavior in a 1D chain.