Amidinium-Containing 2D [MnCr] Dimetallic Oxalate-Based Networks - The Influence on Structure and Magnetism Explored by Combining Experience and Theory

Identifier:  imarina:5131635

Handle: https://hdl.handle.net/20.500.11797/imarina5131635

Authors:  Maxim, Catalin; Saureu, Sergi; de Graaf, Coen; Ferlay, Sylvie; Hosseini, Mir Wais; Robert, Vincent; Train, Cyrille

Abstract:
Three X2+bisamidinium dications are inserted into oxalate-based dimetallic [MnCr] compounds of formula X[MnII(CH3OH)CrIII(ox)3]2·nS [X2+= C14N4H20 2+(cation A2+, compound 1), C14O2N4H20 2+(cation B2+, compound 2), C16N4H24 2+(cation C2+, compound 3); n = 4 (1-2), 2 (3); S = CH3OH (1-2), CH3CN (3); ox = oxalate]. Single-crystal X-ray analysis of 1-3 reveals that Mn-Cr oxalate-bridged dimetallic coordination networks form corrugated two-dimensional (2D) layers based on heptacoordinate MnIIions surrounded by six oxygen atoms from three bis-bidentate oxalate ions and one oxygen atom from a coordinated methanol molecule. In 1-3, the observed coordination environments of the MnIIions are close to capped trigonal prismatic (CTPR-7) according to continuous shape measurements (CSM). Curie-Weiss temperatures of 0.62, 0.42, and 0.54 K for 1-3, respectively, were deduced from the magnetic susceptibility measurements and reveal dominant ferromagnetic exchange interactions. Ab initio calculations up to the DDCI-2 level were performed on [MnCr] dimeric units and allowed the evaluation of the exchange interactions in 1-3.