Cyano-Bridged Homometallic 1-D and Bimetallic 2-D Assemblies:  Synthesis, Structures, and Magnetic Properties of [Ni(baepn)(CN)]_n(ClO₄)_n and [Ni(baepn)]_2n[Fe(CN)₆]_n(H₂O)_8n

Abstract

Cyano-bridged homometallic complex [Ni(baepn)(CN)](n)(ClO(4))(n)(1) and bimetallic complex [Ni(baepn)](2)(n)[Fe(CN)(6)](n)(H(2)O)(8)(n)(2) [baepn = N,N'-bis(2-aminoethyl)-1,3-propanediamine] were synthesized and characterized. 1 crystallizes in the monoclinic space group P2(1)/n with a = 9.560(3) A, b = 10.700(3) A, c = 14.138(9) A, beta = 90.18(6) degrees, and Z = 4; 2 crystallizes in the monoclinic space group P2(1)/c with a = 8.951(2) A, b = 13.672(3) A, c = 14.392(3) A, beta = 98.906(4) degrees, and Z = 4. The complex 1 has one-dimensional structure whose chain vector runs along the b axis with baepn ligands and perchlorate anions alternately arranged up and down in the c direction. The antiferromagnetic nature of 1 was explained in terms of the infinite chain model and Haldane gap, giving g = 2.33, J = -29.4 cm(-1), and the magnitude of Haldane gap E(g) = 5.22 K. The complex 2 that constitutes the first example of 2-D bimetallic assembly of Ni(II) ion and ferrocyanide anion is composed of the neutral layers based on the [Ni(4)Fe(4)] square grid spanning in the bc plane. For 2, the analysis with the Curie-Weiss law in 2-300 K range results in THETA = 0.200 K and the magnetism was explained in terms of the ability of ferrocyanide in the -Ni-NC-Fe-CN-Ni unit to promote ferromagnetic Ni-Ni interaction.

A bimetallic cyano-bridged complex based on nickel(II) and pentacyanidonitrosylferrate(II) precursors: characterization, crystal structure, and magnetic properties

“…The geometry of the ligand sphere of the six coordinate Ni(II) atom is a tetragonally distorted octahedron [29]. The baepn ligands are lined up along the (001) direction such that the dihedral angle between two adjacent NiN 4 best planes is 0°, and the propylene groups of the baepn ligands are positioned in the same manner in the perpendicular direction of the quasi-linear chain in contrast to a previously reported complex containing baepn ligand with alternately positioned propylene moieties in opposite directions [30]. The shortest intra and interchain Ni-Ni separations are as large as 10.302 and 7.864 Å , respectively.…”

Covalent Embedding of Ni2+/Fe3+ Cyanometallate Structures in Silica by Sol–Gel Processing

“…Other examples in the Ni 2+ /Fe 3+ system are [Ni( N ‐men) 2 ] 3 [Fe(CN) 6 ] 2 ⋅ n H 2 O7 and [Ni(cyclam)] 3 [Fe(CN) 6 ] 2 ⋅ n H 2 O (cyclam=1,4,8,11‐tetraazacyclotetradecane),8 which form honeycomb‐like sheets with [Fe(CN 6 )] 3− units at the corners of regular hexagons. [Ni(2,3,2‐tet)] 2 [Fe(CN) 6 ] ⋅ 8 H 2 O (2,3,2‐tet= N,N′‐ bis(2‐aminoethyl)‐1,3‐propanediamine) forms a square grid of {Ni 4 Fe 4 } units 9…”

“…A value of μ eff at room temperature below 6.3 μ B was reported for both ferromagnetic structures. Complex [Ni(2,3,2‐tet)] 2 [Fe(CN) 6 ] ⋅ 8 H 2 O is also ferromagnetic with a maximum μ eff of 4.73 μ B at 6 K, which is only a small increase from the value at room temperature of 4.53 μ B 9…”

“…[Ni(2,3,2-tet)] 2 [Fe(CN) 6 ] ⋅ 8 H 2 O (2,3,2-tet= N,N′- bis(2-aminoethyl)-1,3-propanediamine) forms a square grid of {Ni 4 Fe 4 } units. [ 9 ]…”

“…Complex [Ni(2,3,2-tet)] 2 [Fe(CN) 6 ] ⋅ 8 H 2 O is also ferromagnetic with a maximum μ eff of 4.73 μ B at 6 K, which is only a small increase from the value at room temperature of 4.53 μ B . [ 9 ]…”