Bis-Tris Propane as a New Polydentate Linker in the Synthesis of Iron(III) and Manganese(II/III) Complexes

We describe the synthesis, structure, and magnetic properties of two new complexes, one decanuclear iron(III) cluster and one hexanuclear mixed-valence manganese(II/III) cluster, where the previously unexplored polydentate ligand Bis-tris propane {(CH2OH)3CNH(CH2)3NHC(CH2OH)3} is used to link small cluster fragments into high-nuclearity complexes

Synthesis, Structure, and Magnetic Properties of the Single-Molecule Magnet [Ni₂₁(cit)₁₂(OH)₁₀(H₂O)₁₀]^16-

The preparation of two new compounds containing the cluster [Ni21(cit)12(OH)10(H2O)10]16- is presented, together with a detailed magnetic investigation of one of the compounds. We found that this cluster shows an unexpected stability and that it exists as different stereoisomers. Compound 1 contains the achiral cluster with a Δ−Λ configuration, and compound 2 contains a pair of enantiomeric clusters with the configurations Δ−Δ and Λ−Λ, respectively. Magnetic measurements of 1 in the millikelvin range were necessary to determine the spin ground state of S = 3, and they also revealed a magnetic anisotropy within the ground state. A frequency-dependent out-of-phase signal was found in alternating current susceptibility measurements at very low temperatures, which indicates a slow relaxation of the magnetization. Thus, individual molecules are acting as single magnetic units, which is a rare phenomenon for nickel clusters. The energy barrier exhibited by compound 1 has been calculated to be 2.9 K

Nanoscale Cages of Manganese and Nickel with “Rock Salt” Cores

Nanoscale Cages of Manganese and Nickel with “Rock Salt” Core

High-Spin M²⁺ Carboxylate Triangles from the Microwave

The reaction of M(O2CMe)2·4H2O (M = Ni, Co) with NaN3 in pyridine/MeOH under microwave irradiation and controlled pressure/temperature leads to the formation of the trimetallic species [M3(N3)3(O2CMe)3(py)5] (M = Ni, 1; Co, 2) in 4 min and in high yields. Both complexes display dominant ferromagnetic interactions and high-spin ground states

Exploring the Coordination Chemistry of 3,3′-Di(picolinamoyl)-2,2′-bipyridine: One Ligand, Multiple Nuclearities

The syntheses, structures, and magnetic properties of three new coordination complexes, tetranuclear [Zn₂<b>L</b>^<b>3</b>(OAc)­(OMe)]₂·3MeOH·H₂O (<b>3</b>), trinuclear [Ni₃(<b>L</b>^<b>3</b>)₃]·6H₂O (<b>4</b>), and a 1-D chain {[Cu₂<b>L</b>^<b>3</b>(OAc)₂]₂·H₂O}_n (<b>6</b>), of a polydentate, doubly deprotonated, 3,3′-disubstituted bipyridine ligand [<b>L</b>^<b>3</b><b>]</b>^<b>2‑</b> are reported. The X-ray crystal structures demonstrate that the ditopic ligand provides a flexible N₃ donor set for transition metal ions where each binding pocket shifts from <i>fac</i> to intermediate <i>fac</i>/<i>mer</i> to the <i>mer</i> isomer affording a Ni₃ triangle, a Zn₄ tetramer, and a 1-D Cu­(II) polymer, respectively. This variation in coordination preference is rationalized with the aim of designing future ligands with controlled coordination modes. Magnetic susceptibility studies on <b>4</b> reveal it belongs to the rare family of ferromagnetically coupled [Ni₃] clusters. In contrast, magnetic studies of the 1-D chain <b>6</b> reveal weak antiferromagnetic interactions due to the poor orbital overlap of the singly occupied Cu­(II) d_{<i>x</i>²–<i>y</i>²} orbitals with the one-atom bridge that connects them along the Jahn–Teller distortion axis

Hydroxido-Supported and Carboxylato Bridge-Driven Aggregation for Discrete [Ni₄] and Interconnected [Ni₂]_<i>n</i> Complexes

Four different carboxylato bridges have been efficiently utilized for growth of three tetranuclear nickel­(II) complexes [Ni4(μ3-H2L)2(μ3-OH)2(μ1,3-CH3CO2)2]­(ClO4)2 (1), [Ni4(μ3-H2L)2(μ3-OH)2(μ1,3-C2H5CO2)2]­(ClO4)2·1/2H2O (2), and [Ni4(μ3-H2L)2(μ3-OH)2(μ1,3-O2C-C6H4-pNO2)2]­(ClO4)­(p-NO2-C6H4-CO2)·DMF·5H2O (3) and one dinuclear nickel­(II)-based chain complex {[Ni2(μ-H2L)­(μ1,3-O2CCH2Ph)2(H2O)]­(ClO4)·1/2­(CH3OH)}n (4). These were obtained via the reaction of Ni­(ClO4)2·6H2O with H3L [2,6-bis­((2-(2-hydroxyethylamino)­ethylimino)­methyl)-4-methylphenol] and RCO2Na (R = CH3,C2H5, p-NO2C6H4, and PhCH2). This family of complexes is developed from {Ni2(μ-H2L)}3+ fragments following self-aggregation. The complexes were characterized by X-ray crystallography and magnetic measurements. The changes from acetate, propionate, and p-nitrobenzoate to phenylacetate groups resulted in two different types of coordination aggregation. These compounds are new examples of [Ni4] and [Ni2]n complexes where organization of the building motifs are guided by the type of the carboxylate groups responsible for in-situ generation and utilization of HO– bridges with alteration in the aggregation process within the same ligand environment. Studies on the magnetic behavior of the compounds reveal that the exchange coupling within 1–4 is predominantly antiferromagnetic in nature

High-Spin M²⁺ Carboxylate Triangles from the Microwave

The reaction of M(O2CMe)2·4H2O (M = Ni, Co) with NaN3 in pyridine/MeOH under microwave irradiation and controlled pressure/temperature leads to the formation of the trimetallic species [M3(N3)3(O2CMe)3(py)5] (M = Ni, 1; Co, 2) in 4 min and in high yields. Both complexes display dominant ferromagnetic interactions and high-spin ground states