Magnetic Properties of High-Nuclearity Fe-oxo ( = 7, 22, 24) Clusters Analyzed by a Multipronged Experimental, Computational, and Magnetostructural Correlation Approach.

The synthesis, structure, and magnetic properties of three related iron(III)-oxo clusters are reported, [FeO(OCPh)(mda)(HO)] (), [FeO(OH)(OCMe)(mda)](ClO) (), and [FeO(OH)(OEt)(OCMe)(mda)](ClO) (), where mdaH is -methyldiethanolamine. was prepared from the reaction of [FeO(OCPh)(HO)](NO) with mdaH in a 1:2 ratio in MeCN, whereas and were prepared from the reaction of FeCl/NaOCMe/mdaH in a 2:∼13:2 ratio and FeCl/NaOCMe/mdaH/pyridine in a 2:∼13:2:25 ratio, respectively, both in EtOH. The core of consists of a central octahedral Fe ion held within a nonplanar Fe loop by three μ-O and three μ-RO arms from the three mda chelates.

High-nuclearity, mixed-valence Mn₁₇, Mn₁₈ and {Mn₆₂}n complexes from the use of triethanolamine.

The use of both azide and triethanolamine, with or without the presence of carboxylate groups, has provided new Mn(17), Mn(18) and {Mn(62)}(n) complexes with aesthetically-pleasing cage, layered, and linked-chain-type structures; two are also new single-molecule magnets.

Spin maximization from S = 11 to S = 16 in Mn(7) disk-like clusters: spin frustration effects and their computational rationalization.

The use has been explored in Mn cluster chemistry of N(3)(-) or Cl(-) in combination with N-methyldiethanolamine (mdaH(2)) or triethanolamine (teaH(3)). The reactions of Mn(ClO(4))(2).6H(2)O, NEt(3), NaN(3), and either mdaH(2) or teaH(3) (1:2:1:2) in DMF/MeOH afford {[Na(MeOH)(3)][Mn(7)(N(3))(6)(mda)(6)]}(n) (1) and {Na[Mn(7)(N(3))(6)(teaH)(6)]}(n) (2), respectively, whereas the 2:1:1 reaction of MnCl(2).

Spin maximization: switching of the usual S = 11 state of Mn(II)4Mn(III)3 disklike complexes to the maximum S = 16.

The S = 11 ground states of the Mn 7 family of mixed-valence complexes with a metal-centered hexagonal topology have been found by density functional theory calculations to arise by spin frustration involving small differences in the magnitudes of the two weakest interactions controlling the alignment of the central spin. Targeted structural perturbation has allowed a complex with the central spin flipped to be discovered, which thus possesses the maximum S = 16 ground state.

"Switching on" the properties of single-molecule magnetism in triangular manganese(III) complexes.

The reaction between oxide-centered, triangular [MnIII3O(O2CR)6(py)3](ClO4) (R = Me (1), Et (2), Ph (3)) compounds and methyl 2-pyridyl ketone oxime (mpkoH) affords a new family of Mn/carboxylato/oximato complexes, [MnIII3O(O2CR)3(mpko)3](ClO4) [R = Me (4), Et (5), and Ph (6)]. As in 1-3, the cations of 4-6 contain an [MnIII3(mu3-O)]7+ triangular core, but with each Mn2 edge now bridged by an eta1:eta1:mu-RCO2- and an eta1:eta1:eta1:mu-mpko- group. The tridentate binding mode of the latter causes a buckling of the formerly planar [MnIII3(mu3-O)]7+ core, resulting in a relative twisting of the three MnIII octahedra and the central O2- ion now lying approximately 0.

Four copper(II) pyrazolido complexes derived from reactions of 3{5}-substituted pyrazoles with CuF(2) or Cu(OH)(2).

Treatment of CuF(2) with 2 equiv of 3{5}-[pyrid-2-yl]pyrazole (Hpz(Py)), 3{5}-phenylpyrazole (Hpz(Ph)) or 3{5}-[4-fluorophenyl]pyrazole (Hpz(PhF)) in MeOH, followed by evaporation to dryness and recrystallisation of the solid residues, allows solvated crystals of [{Cu(micro-pz(Py))(pz(Py))}(2)] (1), [{Cu(micro-pz(Ph))(2)}(4)] (2) and [Cu(4)F(2)(micro(4)-F)(micro-pz(PhF))(5)(Hpz(PhF))(4)] (3) to be isolated in moderate-to-good yields. Similar reactions of these three pyrazoles with Cu(OH)(2) in refluxing MeOH respectively afford 1, 2 and [Cu(pz(PhF))(2)(Hpz(PhF))(2)] (4) in ca. 10% yield.

Initial example of a triangular single-molecule magnet from ligand-induced structural distortion of a [MnIII3O]7+ complex.

The reaction of [Mn3O(O2CR)6(py)3](ClO4) (R = Me, Et) with methyl 2-pyridyl ketone oxime (mpkoH) in a 1:3 molar ratio in MeOH/MeCN leads to [Mn3O(O2CR)3(mpko)3](ClO4) in 80-90% isolated yield. Ferromagnetic exchange interactions between the three MnIII ions in the nonplanar [MnIII3O]7+ triangular core lead to a spin ground state of S = 6; single-crystal studies reveal the temperature and sweep rate dependent hysteresis loops expected for a single-molecule magnet.

Direct determination of the anisotropy and exchange splittings in the dimeric single-molecule magnet [Mn4O3Cl4(O2CEt)3(py)3]2.8MeCN by inelastic neutron scattering.

Energy splittings resulting from anisotropy and exchange interactions in the dimer of single-molecule magnets [Mn4O3Cl4(O2CEt)3(py)3]2.8MeCN are determined for both an undeuterated and a partially deuterated sample using inelastic neutron scattering. The antiferromagnetic (AF) exchange coupling between the two Mn4 subunits strongly depends on their separation.

High-nuclearity homometallic iron and nickel clusters: Fe22 and Ni24 complexes from the use of N-methyldiethanolamine.

The use of N-methyldiethanolamine (mdaH2) in reactions with Fe(III) and Ni(II) sources has led to Fe22 and Ni24 products; the clusters are the highest and second-highest, respectively, homometallic clusters for these metals to date, and possess S = 0 and S = 6 ground states, respectively.