TY  - JOUR
AU  - Déniz, M.
AU  - Pasán, J.
AU  - Fabelo, O.
AU  - Cañadillas-Delgado, L.
AU  - Lloret, F.
AU  - Julve, M.
AU  - Ruiz-Pérez, C.
T1  - Metal-organic coordination frameworks based on mixed methylmalonate and 4,4′-bipiridine ligands: Synthesis, crystal structure and magnetic properties
LA  - eng
PY  - 2010
SP  - 2515
EP  - 2527
T2  - New Journal of Chemistry
SN  - 1144-0546
VL  - 34
IS  - 11
AB  - Five new complexes of formulae [M2(4,4′-bpy)(Memal) 2X2]n [M = Fe(iii) (2), Mn(ii) (3), Co(ii) (4), Ni(ii) (5) and Zn(ii) (6), and X = Cl-/OH- (2) and H 2O (3-6); 4,4′-bpy = 4,4′-bipyridine and Memal = methylmalonate dianion] have been synthesized by following the previously reported procedure for [Cu2(4,4′-bpy)(Memal)2(H 2O)2]n (1). Moreover, two new phases of the Cu(ii)/Memal/4,4′-bpy system, namely {[Cu(4,4′-bpy) 2][Cu(4,4′-bpy)2(Memal)(NO3)(H 2O)]}n·nNO3·3.5nH2O (7) and [Cu(4,4′-bpy)2(Memal)(H2O)] n·nH2O (8), were obtained by varying the synthetic conditions. They were all structurally characterized by single crystal X-ray diffraction, and the magnetic properties of 2-5, 7 and 8 were investigated in the temperature range 1.9-295 K. 1-6 are isomorphous compounds whose structure consists of square grids of metal ions linked through anti-syn carboxylate bridges that grow in the crystallographic ac plane. These layers are pillared along the b axis by bis-monodentate 4,4′-bpy ligands to afford a [4 466]-sqp three-dimensional net. Ferro- (1 and 5) and antiferromagnetic (2-4) interactions between the metal ions are mediated by the carboxylate bridge in the anti-syn conformation, the bis-monodentate 4,4′-bpy ligand being unable to transmit a significant magnetic coupling. The values of the magnetic coupling (J) for 2-5 are -0.269(3), -0.225(2), -0.05 and +0.272(3) cm-1 respectively, the isotropic spin Hamiltonian being. Complexes 7 and 8 exhibit quite a different structure, as driven by the 4,4′-bpy groups. A square-grid of [Cu(4,4′-bpy)2] 2n+n occurs in 7, which grows in the ab plane and is pillared through anti-syn carboxylate bridges from [Cu(Memal)(4,4′-bpy) 2(NO3)(H2O)] units along the c axis to build up a [41263]-pcu net. Analysis of the magnetic data for this compound shows an overall antiferromagnetic behaviour with the coexistence of ferro- and antiferromagnetic interactions. The structure of 8 consists of linear chains of copper(ii) running along the c axis, where aquabis(4,4′- bipyridine)copper(ii) units are connected by bis(monodentate) methylmalonate ligands. A significant intrachain antiferromagnetic interaction is observed in 8 through the extended Cu-OCCCO-Cu exchange pathway [J = -1.38(1) cm -1]. The assembling role of the 4,4′-bpy coligand in 1-8 and in previous malonate-containing complexes is analyzed and discussed. © 2010 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
DO  - 10.1039/c0nj00436g
UR  - https://portalciencia.ull.es/documentos/5e3c35a529995246bbf5d7b9
DP  - Dialnet - Portal de la Investigación
ER  -