Structural and Magnetic Properties of Cu[C(CN)₃]₂ and Mn[C(CN)₃]₂

Abstract

Single-crystal X-ray structure analyses and the measurements of static magnetic susceptibility and ESR have been performed for the title compounds. Crystal data: for Cu[C(CN)3]2, space group Pmna, a = 7.212(5) Å, b = 5.452(7) Å, c = 10.696(7) Å, and Z = 2; for Mn[C(CN)3]2, space group Pmna, a = 7.742(5) Å, b = 5.411(6) Å, c = 10.561(6) Å, and Z = 2. Both salts are essentially isostructural. The Cu atoms are bridged by two [C(CN)3]- anions to form an infinite double chain structure, in which Cu has a square planar coordination (d Cu - N = 1.986(6) Å). The third CN end of the anion is weakly coordinated to the adjacent Cu chain (d Cu - N = 2.47(1) Å), making a three-dimensional network. The crystal is composed of two such interwoven networks. In the Mn complex, the third Mn−N distance (2.256(6) Å) is as short as the equatorial coordinations (2.236(4) Å), so that Mn is coordinated octahedrally. These compounds exhibit paramagnetic behavior following the Curie−Weiss law with Weiss temperatures −1.4 and −9 K, respectively, and the Mn complex undergoes an antiferromagnetic transition at T N = 5 K.

Unusual magnetic-field dependence of partially frustrated triangular ordering in manganese tricyanomethanide

“…Here we describe heat capacity and neutron diffraction studies of the magnetic ordering below 1.18 K in Mn[C(CN) 3 ] 2 . A previous report of an antiferromagnetic transition for Mn[C(CN) 3 ] 2 at T N = 5 K [9] could not be confirmed by the present work.…”

“…The tricyanomethanide anion, C(CN) 3 -, has three-fold symmetry and therefore appears to be an ideal candidate. Recently, the synthesis and magnetic properties of the series M[C(CN) 3 ] 2 , with M = transition metal, has been reported [7][8][9][10][11]. As described in detail below, these compounds may be regarded as examples for partially frustrated triangular lattices represented by the "row model" introduced by Kawamura [12] and Zhang et al [13].…”

“…The critical behavior of Cr[C(CN) 3 ] 2 is consistent with the 2D Ising model. No ordering above 2 K was observed in V[C(CN) 3 ] 2 [10] as well as the Cu, Ni and Co compounds [9,11]. Here we describe heat capacity and neutron diffraction studies of the magnetic ordering below 1.18 K in Mn[C(CN) 3 ] 2 .…”

Synthesis and Crystal Structure of KLa[C(CN)3]4·H2O containing a Shielded Potassium Ion

“…For example, compounds M[N(CN) 2 ] 2 with divalent M ϭ Cr, Mn, Co, Ni, Cu [3,4,5] have shown ferromagnetic properties with ordering temperatures between 9 and 47 K [1]. Tricyanomethanide (tcm) compounds M[C(CN) 3 ] 2 have been reported with M ϭ V, Cr, Mn, Fe, Co, Ni, Cu [6,7,8,9] to form interpenetrating network structures, with antiferromagnetic coupling between metal centers, due to spin-frustrations related with trigonal metal bridging of the tcm ions in these structures [1,9].…”

Synthesis, crystal structure and magnetism of a three-dimensional manganese(II) complex with carbamyldicyanomethanide anion (cda) as a bridging ligand

“…Polynitrile compounds such as tricyanomethanide [5][6][7], dicyanamide [8][9][10][11][12][13][14][15], 7,7,8,8-tetracyanoquinodimethane [16][17][18][19][20][21], 1,2,4,5-tetracyanobenzene [22,23] and tetracyanoethene [24][25][26][27][28] display versatile bridging modes and many coordination compounds have been constructed from such polynitriles and metal ions, some of them exhibiting the distinguished magnetic properties [24]. Although some complexes with cda as ligand have been synthesized and their crystal structures determined by X-ray crystallography [29][30][31][32], no magnetic property of the cda bridging manganese ion complexes has been reported.…”