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Synthesis, Thermal and Magnetic Properties of New Coordination Compounds based on Mn(NCS) 2 with 2‐Chloropyrazine and 2‐Methylpyrazine as neutral Co‐Ligand
Author(s) -
Wöhlert Susanne,
Runčevski Tomče,
Dinnebier Robert E.,
Näther Christian
Publication year - 2013
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201300361
Subject(s) - manganese , chemistry , thiocyanate , crystallography , ligand (biochemistry) , coordination complex , cobalt , composition (language) , crystal structure , stereochemistry , inorganic chemistry , metal , organic chemistry , biochemistry , linguistics , receptor , philosophy
Reaction of manganese(II) thiocyanate with 2‐chloropyrazine leads always to the formation of a compound of composition Mn(NCS) 2 (2‐chloropyrazine) 4 ( 1 ‐ Mn/Cl ) that consists of discrete complexes, in which the manganese cation is coordinated by two terminal thiocyanato anions and four 2‐chloropyrazine ligands. In contrast, with 2‐methylpyrazine only an aqua complex of composition Mn(NCS) 2 (2‐methylpyrazine) 2 (H 2 O) 2 ( 1 ‐ Mn/CH 3 ) is obtained that also consists of discrete octahedrally coordinated complexes. Moreover, a few single crystals of Mn(NCS) 2 (2‐chloropyrazine) 4 · Mn(NCS) 2 (2‐chloropyrazine) 2 (H 2 O) 2 · 2‐chloropyrazine trisolvate ( 2 ‐ Mn/Cl ) and Mn(NCS) 2 (2‐methylpyrazine) 2 (H 2 O) 2 · Mn(NCS) 2 (H 2 O) 4 ( 2 ‐ Mn/CH 3 ) were accidently obtained but no larger amounts are available. On heating, 1 ‐ Mn/Cl and 1 ‐ Mn/CH 3 transforms into new compounds of composition Mn(NCS) 2 (L) 2 (L = 2‐chloropyrazine) ( 4 ‐ Mn/Cl ) and 2‐methylpyrazine ( 3 ‐ Mn/CH 3 ). Surprisingly on further heating 1 ‐ Mn/CH 3 looses additional 2‐methylpyrazine ligands and transforms into a new compound of composition Mn(NCS) 2 (2‐methylpyrazine) ( 4 ‐ Mn/CH 3 ). Compound 4 ‐ Mn/Cl is isotypic to its cobalt(II) analog and 4 ‐ Mn/CH 3 is isotypic to Cd(NCS) 2 (2‐methylpyrazine) reported recently and therefore, both structures were refined by the Rietveld method. The crystal structures of both compounds are strongly related. They consists of dimeric units, in which each two manganese cations are linked by pairs of μ‐1, 3‐bridging thiocyanato anions, which are further connected into layers by single μ‐1, 3‐bridging anionic ligands. In contrast to 4 ‐ Mn/Cl , in 4 ‐ Mn/CH 3 these layers are further linked into a 3D coordination network by the 2‐methylpyrazine ligands. Magnetic measurements reveal that 1 ‐ Mn/Cl , 1 ‐ Mn/CH 3 , and 3 ‐ Mn/CH 3 shows only Curie‐ or Curie‐Weiss paramagnetism, whereas 4 ‐ Mn/Cl and 4 ‐ Mn/CH 3 shows antiferromagnetic ordering at T N = 22.9 K and at 26.5 K. The results of these investigations are compared with those obtained for related compounds.