Unusual Structural Types in Nickel Cluster Chemistry from the Use of Pyridyl Oximes: Ni₅, Ni₁₂Na₂, and Ni₁₄ Clusters

Abstract

Syntheses, crystal structures, and magnetochemical characterization are reported for the three new nickel(II) clusters [Ni(14)(OH)(4)(N(3))(8)(pao)(14)(paoH)(2)(H(2)O)(2)](ClO(4))(2) (1), [Ni(12)Na(2)(OH)(4)(N(3))(8)(pao)(12)(H(2)O)(10)](OH)(2) (2), and [Ni(5)(ppko)(5)(H(2)O)(7)](NO(3))(5) (3) (paoH = pyridine-2-carbaldehyde oxime, ppkoH = di-2-pyridyl ketone oxime). The reaction of Ni(ClO(4))(2).6H(2)O with paoH and NBu(n)(4)N(3) in H(2)O/MeCN in the presence of NEt(3), gave 1 in 65% yield. Complex 2 was obtained in 60% yield from the reaction of NiCl(2).6H(2)O with paoH and NaN(3) in H(2)O/MeCN in the presence of NaOH. The reaction of Ni(NO(3))(2).6H(2)O with ppkoH in EtOH in the presence of LiOH afforded complex 3 in 75% yield. The complexes all contain novel core topologies. The core of 1 comprises a central Ni(4) rhombus between two Ni(5). Complex 1 is the largest metal/oxime cluster discovered to date, as well as the first Ni(II)(14) coordination complex and the largest Ni(II)/N(3)(-) cluster. Complex 2 has a Ni(12)Na(2) topology that is very similar to that of 1, but with two central Ni(II) atoms of 1 replaced with Na(I) atoms. The core of 3 consists of four Ni(II) atoms forming a highly distorted tetrahedron, with the fifth Ni(II) atom lying almost on one of the edges. Variable-temperature, solid-state dc susceptibility and magnetization studies were carried out on complexes 1-3, and these were complemented with ac susceptibility data for 1 and 2. Fitting of the obtained M/(Nmu(B)) vs H/T data by matrix diagonalization and including axial zero-field splitting (D) gave ground-state spin (S) and D values of S = 6, D = -0.12(3) cm(-1) for 1 and S = 3, D = -0.20(5) cm(-1) for each of the two essentially noninteracting S = 3 Ni(6) subunits of 2. The data for 3 indicate antiferromagnetic exchange interactions and an S = 1 ground state. A simple 2-J model was found to be adequate to describe the variable-temperature dc susceptibility data. The combined work demonstrates the ligating flexibility of pao(-) and ppko(-), and their usefulness in the synthesis of polynuclear Ni(x) clusters with or without the presence of ancillary ligands.

Synthesis, crystal structures, hydrogen bonding graph-sets and theoretical studies of nickel (+II) co-ordinations with pyridine-2,6-dicarboxamide oxime

“…The chemistry of oxime-based ligand is diverse [11]. Introduced first in 1905 by Tschugaeff [12], dimethylglyoxime as a reagent for nickel, the oximes as potential ligands have been increasingly expanding its horizon in coordination chemistry.…”

A Ni11 Coordination Cluster from the Use of the Di-2-Pyridyl Ketone/Acetate Ligand Combination: Synthetic, Structural and Magnetic Studies

“…This 3d 8 metal ion has shown promise in the synthesis of SMMs [7] and spin-phonon traps [10], with the former taking advantage of its significant single-ion anisotropy and the latter of its paramagnetic nature when the metal ion is confined in a highly symmetric cluster. These characteristics justify the interest of our groups in the chemistry of nickel(II) coordination clusters [11][12][13][14][15].…”

“…While the number of high-nuclearity, non-organometallic complexes of nickel(II) with O-and/or N-based ligands and without metal-metal bonding continues to grow rapidly [11,15,[29][30][31][32][33] (the record nuclearity is 26 [29]), some nuclearities remain rare. Undecanuclear nickel(II) complexes are particularly rare, and complex 1 thus becomes a new member of the small family of Ni 11 clusters [34][35][36][37][38]; the metal topology and core of 1 are novel.…”

“…This alignment, based on the above discussion, leads to the S = 3 ground state. In order to provide a qualitative explanation of the magnetic properties of 1, we assume as main interactions those provided by the monatomic oxygen bridges, which can be analyzed based on wellestablished magnetostructural correlations in nickel(II) complexes [11][12][13][14][15]18,[20][21][22]34,[39][40][41][42][43][44][45][46][47][48][49]. The linkage between the external cubanes and the central Ni3 subunit involves four Ni-O(hydroxido)-Ni units (Figure 3) with bond angles in the 117.1°-125.3°; these angles are expected to propagate antiferromagnetic exchange interactions.…”

Synthesis, quantum chemical computations and x-ray crystallographic studies of a new complex based of manganese (+II)

“…The chemistry of oxime-based ligand is diverse [1]. Introduced first in 1905 by Tschugaeff [2], e.g.…”