Structures and Magnetic Properties of an Antiferromagnetically Coupled Polymeric Copper(II) Complex and Ferromagnetically Coupled Hexanuclear Nickel(II) Clusters

Abstract

Reactions between 2,6-diformyl-4-methylphenol (DFMF) and tris(hydroxymethyl) aminomethane (THMAM = H(3)L2) in the presence of copper(II) salts, CuX(2) (X = CH(3)CO(2)(-), BF(4)(-), ClO(4)(-), Cl(-), NO(3)(-)) and Ni(CH(3)CO(2))(2) or Ni(ClO(4))(2)/NaC(6)H(5)CO(2), sodium azide (NaN(3)), and triethylamine (TEA), in one pot self-assemble giving a coordination polymer consisting of repeating pentanuclear copper(II) clusters {[Cu(2)(H(5)L(2-))(μ-N(3))](2)[Cu(N(3))(4)]·2CH(3)OH}(n) (1) and hexanuclear Ni(II) complexes [Ni(6)(H(3)L1(-))(2)(HL2(2-))(2)(μ-N(3))(4)(CH(3)CO(2))(2)]·6C(3)H(7)NO·C(2)H(5)OH (2) and [Ni(6)(H(3)L1(-))(2)(HL2(2-))(2)(μ-N(3))(4)(C(6)H(5)CO(2))(2)]·3C(3)H(7)NO·3H(2)O·CH(3)OH (3). In 1, H(5)L(2-) and in 2 and 3 H(3)L1(-) and HL2(2-) represent doubly deprotonated, singly deprotonated, and doubly deprotonated Schiff-base ligands H(7)L and H(4)L1 and a tripodal ligand H(3)L2, respectively. 1 has a novel double-stranded ladder-like structure in which [Cu(N(3))(4)](2-) anions link single chains comprised of dinuclear cationic subunits [Cu(2)(H(5)L(2-))(μ-N(3))](+), forming a 3D structure of interconnected ladders through H bonding. Nickel(II) clusters 2 and 3 have very similar neutral hexanuclear cores in which six nickel(II) ions are bonded to two H(4)L1, two H(3)L2, four μ-azido, and two μ-CH(3)CO(2)(-)/μ-C(6)H(5)CO(2)(-) ligands. In each structure two terminal dinickel (Ni(2)) units are connected to the central dinickel unit through four doubly bridging end-on (EO) μ-azido and four triply bridging μ(3)-methoxy bridges organizing into hexanuclear units. In each terminal dinuclear unit two nickel centers are bridged through one μ-phenolate oxygen from H(3)L1(-), one μ(3)-methoxy oxygen from HL2(2-), and one μ-CH(3)CO(2)(-) (2)/μ-C(6)H(5)CO(2)(-) (3) ion. Bulk magnetization measurements on 1 show moderately strong antiferromagnetic coupling within the [Cu(2)] building block (J(1) = -113.5 cm(-1)). Bulk magnetization measurements on 2 and 3 demonstrate that the magnetic interactions are completely dominated by ferromagnetic coupling occurring between Ni(II) ions for all bridges with coupling constants (J(1), J(2), and J(3)) ranging from 2.10 to 14.56 cm(-1) (in the Ĥ = -J(1)(Ŝ(1)Ŝ(2)) - J(1)(Ŝ(2)Ŝ(3)) - J(2)(Ŝ(3)Ŝ(4)) - J(1)(Ŝ(4)Ŝ(5)) - J(1)(Ŝ(5)Ŝ(6)) - J(2)(Ŝ(1)Ŝ(6)) - J(3)(Ŝ(2)Ŝ(6)) - J(3)(Ŝ(2)Ŝ(5)) - J(3)(Ŝ(3)Ŝ(5)) convention).

Synthesis, crystal structures, and antimicrobial activity of copper(II) and zinc(II) complexes derived from 2-bromo-4-chloro-6-[(2-morpholin-4-ylethylimino)methyl]phenol

“…The azide anion acts as an end-to-end bidentate ligand, which coordinates to two Cu atoms through two terminal N atoms. The bond distances subtended at the Cu atoms are comparable to those observed in the similar copper(II) complexes with Schiff bases [16][17][18].…”

A Discrete Nickel Cubane with [Ni4O4] Cluster: Synthesis, Structure, and Magnetic Property

“…All the Ni atoms are six coordinated with a distorted octahedral coordination polyhedron, in which three oxygen atoms act as bridges to connect the other remaining three Ni atoms. Up to now, many Ni II cluster-based compounds have been previously reported, such as {Ni 2 }clusters, [14] liner-shaped {Ni 3 }clusters, [15] triangle-shaped {Ni 3 }clusters linked by μ 3 -O atom, [16] rhombus-shaped {Ni 4 }clusters, [17] cubane-like {Ni 4 }clusters, [18] {Ni 5 }clusters with rectangular symmetry, [19] {Ni 6 } clusters constructed by two {Ni 3 }clusters and so on, [10,20] all of which exhibit various magnetic behaviors.…”

“…[2] Up to now, many different kinds of transition metallic clusters have been studied, such as {Co 3 }, [3] {Ni 4 }, [4] {Zn 8 }, [5] {Cu 10 }, [6] {Mn 12 }, [7] or {Fe 18 }, [8] of which some polynuclear clusters display interesting structure types and properties. Among the reported clusters, the tetranuclear cubane like {M 4 O 4 } clusters (M = Cu, Ni, Co, etc.)…”

“…For example, Tandon et al prepared two novel hexanuclear nickel clusters by use of different Schiff-base ligands in 2012. [10] Moreover, Das et al synthesized a series of di-, tri-, and tetranuclear Ni II compounds based on two tridentate Schiff-base ligands. [11] In this contribution, a tridentate Schiff- Supporting Information) (Scheme 1), prepared by condensation of benzoylacetone and 2-aminophenol, was selected to construct Ni cluster with the following considerations: (1) The acylhydrazone Schiff-base ligands with polydentate N,O-donor are especially favorable for the construction of polynuclear transition metal complexes.…”

“…In order to construct polynulear complexes, polydentate ligands, especially Schiff‐base ligands have been widely explored. For example, Tandon et al prepared two novel hexanuclear nickel clusters by use of different Schiff‐base ligands in 2012 10. Moreover, Das et al synthesized a series of di‐, tri‐, and tetranuclear Ni II compounds based on two tridentate Schiff‐base ligands 11…”