Magneto-Structural Correlation in a Series of Bimetallic Alternating Chain Complexes of [Cr~(III)L(CN)4]n[Mn~(III)(salpn)]n centre dot nSolvents (L = 2,2'-bipy or 9,10-phen,salpn = Substituted Salicyldehyde,Solvents = Water and Methanol)

摘要

Five chain compounds based on the building block of [Cr(L)(CN)4]~- (L = 2,2'-bipy,1-4;L = 9,10-phen,5) and [Mn(salpn)]+ (salpn = substituted salicyldehyde-type Schiff base in Scheme 1) have been prepared and characterized structurally and magnetically.The four compounds (1-4) consisting of [Cr(bipy)(CN)4]~- units possess straight bimetallic chains as the [Cr(bpy)(CN)4]~- unit links the two neighbor [Mn(salpn)]+ units with the two trans-cyanide ligands,while in 5 the chain is zigzag because the [Cr(phen)(CN)4]_ unit connects the [Mn(salpn)]+ units with its two cis-cyanide ligands.The bond angles of Mn-N-C-Cr are adjusted by different coligands of salpn and bipy/phen.The chains are stacking via mainly the aromatic jr-jr-type interactions.All compounds show 3D antiferromagnetic ordering with Neel temperatures ranging from 3.7 to 8.1 K,and they are metamagnets displaying antiferromagnetic to ferrimagnetic transition at critical fields of 4.0-13.1 kOe at 1.9 K.This is due to weak interchain antiferromagnetic interactions between the ferrimagnetic bimetallic chains in the materials.The intrachain couplings (J,in cm~(-1)) in the materials,between cyanide-bridged Cr~(III) and Mn~(III) ions,from -1.84 to -5.35 cm~(-1),follow a linear relationship (J - -33 + 0.18a) to the Mn-N-C angles (a,in deg).In addition,the weak interchain antiferromagnetic interactions and critical fields for antiferromagnetic-ferrimagnetic transition are closely related to some of their structural factors,which were studied very superficially only referring to the separations of nearest chains in each material.