文摘
Three X2+ bisamidinium dications are inserted into oxalate-based dimetallic [MnCr] compounds of formula X[MnII(CH3OH)CrIII(ox)3]2·nS [X2+ = C14N4H202+ (cation A2+, compound 1), C14O2N4H202+ (cation B2+, compound 2), C16N4H242+ (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 MnII ions 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 MnII ions 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.