Structural and Magnetic Properties of Two Carboxylato‐Bridged Manganese(II) Complexes with N‐Donor Coligands

Abstract

AbstractTwo polymeric MnII complexes, [(m‐phth)(Mn)(bpp)2]·0.5H2O (1) and [(mal)2(Mn)2(H2O)2(hmt)] (2) [mal = malonate; hmt = hexamethylenetetramine; bpp = 1,3‐bis(4‐pyridyl)propane; m‐phth = 1,3‐benzenedicarboxylate] have been synthesized. Complex 1 consists of 1D chains (with monocoordinated bpp) that are held together to form a 2D extended network of hydrogen bonding between lattice water molecules and uncoordinated bpp donors. Variable‐temperature magnetic susceptibility data of the complex have been fitted applying the formula used for dinuclear complexes of MnII ions, considering interdimer interactions (J′). The following parameters were obtained from the best fit: J = −0.88 ± 0.02 cm−1, J′ = −0.1 cm−1 and g = 1.99 ± 0.01. The agreement factor R = Σ(χmTobsd. − χmTcalcd.)2/Σ(χmTcalcd.)2 is 1.110−5. Complex 2 is a 3D polymeric network where syn/anti‐bridging malonate ligands and MnII centers are assembled in the form of [Mn(H2O)(mal)]n layers, which are further connected by hexamethylenetetramine. The magnetic data have been fitted considering the complex as a pseudo‐two‐dimensional sheet of MnII cations and malonate anions since the coupling through the hexamethylenetetramine ligand is almost zero. We have followed two approaches for fitting the data, (a) through the expansion series of Line’s equation for the S = 5/2 antiferromagnetic quadratic layer and (b) by using the equation based on an infinite 2D square lattice composed of isotropically coupled classical spin S = 5/2. Both approaches result in excellent theoretical fits and similar J values of −0.24 cm−1 and −0.21 cm−1 for the Line’s and Curély equations, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)