Mn -Acetate Complexes Studied as Single Molecules.

The phenomenon of single molecule magnet (SMM) behavior of mixed valent Mn coordination clusters of general formula [Mn Mn O (RCOO) (H O) ] had been exemplified by bulk samples of the archetypal [Mn Mn O (CH COO) (H O) ] (4) molecule, and the molecular origin of the observed magnetic behavior has found support from extensive studies on the Mn system within crystalline material or on molecules attached to a variety of surfaces. Here we report the magnetic signature of the isolated cationic species [Mn O (CH COO) (CH CN)] (1) by gas phase X-ray Magnetic Circular Dichroism (XMCD) spectroscopy, and we find it closely resembling that of the corresponding bulk samples. Furthermore, we report broken symmetry DFT calculations of spin densities and single ion tensors of the isolated, optimized complexes [Mn O (CH COO) (CH CN)] (1), [Mn O (CH COO) ] (2), [Mn O (CH COO) (H O) ] (3), and the complex in bulk geometry [Mn Mn O (CH COO) (H O) ] (5).

The spin and orbital contributions to the total magnetic moments of free Fe, Co, and Ni clusters.

We present size dependent spin and orbital magnetic moments of cobalt (Con (+), 8 ≤ n ≤ 22), iron (Fen (+), 7 ≤ n ≤ 17), and nickel cluster (Nin (+), 7 ≤ n ≤ 17) cations as obtained by X-ray magnetic circular dichroism (XMCD) spectroscopy of isolated clusters in the gas phase. The spin and orbital magnetic moments range between the corresponding atomic and bulk values in all three cases. We compare our findings to previous XMCD data, Stern-Gerlach data, and computational results.

Orbit and spin resolved magnetic properties of size selected [ConRh]⁺ and [ConAu]⁺ nanoalloy clusters.

Bi-metallic nanoalloys of mixed 3d-4d or 3d-5d elements are promising candidates for technological applications. The large magnetic moment of the 3d materials in combination with a high spin-orbit coupling of the 4d or 5d materials give rise to a material with a large magnetic moment and a strong magnetic anisotropy, making them ideally suitable in for example magnetic storage devices. Especially for clusters, which already have a higher magnetic moment compared to the bulk, these alloys can profit from the cooperative role of alloying and size reduction in order to obtain magnetically stable materials with a large magnetic moment.

Inverse H/D isotope effects in benzene activation by cationic and anionic cobalt clusters.

Reactions under single collision conditions with benzene C(6)H(6) and with benzene-d(6) C(6)D(6) of size selected cationic cobalt clusters Co(n)(+) and of anionic cobalt clusters Co(n)(-) in the cluster size range n = 3-28 revealed that dehydrogenation by cationic clusters is sparse, whereas it is ubiquitous in reactions by anionic clusters. Kinetic isotope effects (KIE) in total reaction rates are inverse and, in part, large. Dehydrogenation isotope effects (DIE) are normal.