Manganese(II) Trimeric Systems Derived from Pyridyldioximato Ligands: Synthesis, Crystal Structure, and Magnetic Characterization

Abstract

Three new manganese compounds have been obtained by reaction of the 2,6‐diacetylpyridine dioxime (dapdoH2) ligand with several MnII salts. By using a variety of manganese(II) carboxylates, three MnII derivatives with general formula [Mn3(RCOO)6(dapdoH2)2], where RCOO– = formate (1), acetate (2), and benzoate (3), were obtained. Structural analysis reveals chains of trinuclear units for 1 and isolated trinuclear molecules for 2. Compound 1 provides an example of a new topology for the [Mn3(RCOO)6(L)2] general formula. Magnetic susceptibility studies reveal topological ferrimagnetism for 1 and conventional antiferromagnetic response for 2 and 3, with coupling constants of –3.1, –3.2, and –1.4 cm–1 inside the trimeric units of 1, 2, and 3, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Two new carboxylate–oxygen bridged trinuclear M(II) (MMn and Co) compounds with zwitterionic dicarboxylate ligands: crystal structures and magnetism

“…In the previous related reports, we note that although a dozen of compounds with similar bridges were characterized structurally and magnetically, no unambiguous correlations were found between the structural parameters (such as Mn-O bridge -Mn angles and the bond parameters of the syn-syn carboxyalte bridges) and the J values due to the complexity arising from the coexistence of mixed oxygen and carboxylate bridges, the presence of unpaired five electrons per Mn(II) and the effects of the terminal ligands. Compound 1 shows a relatively weaker interaction than the previous compounds which may be accounted for the longer Mn-O bridge distance (2.37 Å, 2.49 Å) and the Mn⋯Mn distance (3.69 Å, 3.76 Å) spanned by the mixed bridges than those (2.18-2.33 Å for Mn-O bridge and 3.43-3.69 Å for Mn⋯Mn distance) for the previous reported compounds [23][24][25][26][36][37][38][39].…”

A Single‐Chain Magnet Tape Based on Hexacyanomanganate(III)

“…Crystal data for 1:C 48 H 42 Mn 3 N 12 O 12 , M w = 1143.76 gmol À1 ,t riclinic,space group P1 , a = 8.4873 (17), b = 11.710(2), c = 13.099 (3) , a = 98.891 (12), b = 104.418 (11), g = 104.768 (11) 8 8, V = 1185.7(4) 3 , Z = 1, m = 7.073 mm À1 , 1 calcd = 1.602 Mg m À3 , R 1 = 0.0456, wR 2 = 0.1131.…”

“…[9,7c] This anion is quite intriguing because of the presence of unquenched orbital angular momentum originating from first-order spinorbit coupling of the low-spin (LS) t 2g 4 Mn III ion, which endows it with significant single-ion anisotropy.T his anionic building block is ap romising candidate for both SMMs and SCMs,provided the chemistry can be controlled. [12] We postulated that the labile acetate bridging ligands could be replaced with [Mn(CN) 6 ] 3À anions,a nd that the chelating tptz ligands would serve to prevent the extension of the structure to atwo-dimensional layered motif (Scheme 1). [10] Theoretical studies based on this compound led to the prediction that al inear trinuclear molecule containing the Mn II ÀNCÀ Mn III ÀCNÀMn II unit should exhibit an SMM barrier height larger than 100 K, ah ypothesis that has yet to be tested.…”

A Single‐Chain Magnet Tape Based on Hexacyanomanganate(III)

“…Crystal data for 1:C 48 H 42 Mn 3 N 12 O 12 , M w = 1143.76 gmol À1 ,t riclinic,space group P1 , a = 8.4873 (17), b = 11.710 (2), c = 13.099 (3) , a = 98.891 (12), b = 104.418 (11), g = 104.768(11)8 8, V = 1185.7(4) 3 , Z = 1, m = 7.073 mm À1 , 1 calcd = 1.602 Mg m À3 , R 1 = 0.0456, wR 2 = 0.1131.…”

“…We initiated this work by targeting the use of the centrosymmetric linear trinuclear compound [(tptz) 2 Mn II 3 (OAc) 6 ](1,tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazine), which contains two different environments for the Mn II ions. [12] We postulated that the labile acetate bridging ligands could be replaced with [Mn(CN) 6 ] 3À anions,a nd that the chelating tptz ligands would serve to prevent the extension of the structure to atwo-dimensional layered motif (Scheme 1). Indeed, slow diffusion of { [18-C-6 K} 3 [Mn(CN) 6 ] into 1 affords the unusual compound {[(tptz)Mn II (H 2 O)-Mn III (CN) 6 ] 2 Mn II (H 2 O) 2 } n ·4n MeOH·2n H 2 O( 2 )w ith at apelike chain structure.Magnetic studies revealed that 2 exhibits long-range magnetic ordering below 5.1 Kthat is due to both intra-and inter-chain antiferromagnetic couplings as well as SCM behavior at lower temperatures with an effective energy barrier of 40.5(7) K.…”