Previously, it was demonstrated that besides the covalent bonds also hydrogen bonds (HBs) can be considered as additional paths for the magnetic exchange interactions [1, 2]. The study of magnetic and thermodynamic properties of structurally 1D compound Cu(en)2Ni(CN)4 (en = ethane-1,2-diamine) in the low temperature region confirmed its magnetically 2D character, the present HBs of the N-H···N type were suggested as additional exchange paths to the covalent bonds through the five-atomic -NC-M-CN- bridge [3]. Weak character of the magnetic exchange interactions is in line with long exchange path. We have undertaken a study of a series copper(II) compounds in which [M(CN)4]2– bridging species with square coordinated diamagnetic M(II) atoms were replaced by [MnCl4]2– anion. The use of this anion allows the formation of Cu(II)-Mn(II) bimetallic chains with short bridge between the paramagnetic atoms consisted of one chloride ligand. These systems are interesting from magnetic point of view, chains of Mn(II) (S = 5/2) and Cu(II) (S = l/2) structurally ordered in an alternating manner are of intense interest as potential starting blocks in the synthesis of molecular-based ferromagnets [4].
We have prepared and structurally characterized three novel compounds using the methyl derivates of ethylenediamine: Cu(men)2MnCl4 (1), Cu(bmen)2MnCl4 (2) and Cu(dmen)2MnCl4 (3) (men = N-methylethane-1,2 diamine; bmen = N,N’-dimethylethane-1,2 diamine; dmen = N,N-dimethylethane-1,2-diamine). Compounds 1 and 2 exhibit chain-like structures analogous to the already reported Cu(en)2MnCl4 [5] in which alternating Cu(II) and Mn(II) atoms are bridged by chloride ligand. The hexa-coordinated Cu(II) atom is surrounded by two chelate bonded blocking ligands and two chloride ligands are placed in the trans positions, the Mn(II) coordination environment approximates tetrahedral symmetry. On the other hand, the use of the unsymmetrical dmen ligand leads to a dinuclear compound 3 with molecular structure in which the pentacoordinated Cu(II) and tetrahedrally coordinated Mn(II) atoms are linked by one bridging chlorido ligand. Further details on the syntheses, characterizations and crystal structures will be given.
1. J. Kuchár, J. Černák, Z. Mayerová, P. Kubáček, Z. Žák, Solid State Phenom., 90-91, (2003), 328.
2 E. Čižmár, A. Orendáčová, M. Orendáč, J. Kuchár, M. Vavra, I. Potočňák, J. Černák, E. Casini, A. Feher, Phys. Status Sol. B, 243, (2006), 268.
3. M. Orendáč, A. Orendáčová, J. Černák, A. Feher, Solid State Commun, 94, (1995), 833.
4. H. O. Stumpf, Y. Pei, O. Kahn, J. Sletten, J. P. Renard, J. Am. Chem. Soc., 115, (1993), 6738.
5. B. Chiari, A. Cinti, O. Piovesana, P. F. Zanazzi, Inorg Chem., 34(10)(1995). 34(10), 2652.
This work was supported by P. J. Šafárik University in Košice (VVGS-PF-2016-72623, VVGS-2016-265).