Molecular Magnetic Quantum Dots in Multivalent Metal Cluster Compounds

Abstract

In most magnetic molecular clusters studied so far, localized moments of metal ions are coupled by superexchange interactions via ligand atoms to yield the total moment of the cluster, which is basically a piece of a magnetic insulator. Here we present an experimental and theoretical study of another form of molecular magnetism, arising from unfilled molecular orbitals delocalized over the entire metal cores of molecular metal clusters. These cores thus act as nanosize quantum dots, in which the metal valence electrons are confined. [S0031-9007 (98)07157-9]

High‐Temperature Experimental and Theoretical Study of Magnetic Interactions in Diamond and Pseudo‐Diamond Frameworks Built up from Hexanuclear Tantalum Clusters

“…(9)] were tested as model functions for c spin due to their better analytical behaviour in the region in which T is comparable to j J j /k. Such a procedure has already been suggested in the literature [27] and is also used in computer software designed for fitting measured magnetic-susceptibility data according to HTSE approach.…”

“…[8] The [M 6 L i 12 L a 6 ] clusters with fifteen electrons per cluster belong to an unusual class of materials that have one unpaired electron delocalised over whole metal-cluster units that can generate interesting magnetic properties. [9] Indeed, the unpaired electron lies in the molecular orbital of a 2u symmetry, delocalised mainly over metallic atoms and, to some extent over inner halide atoms. [10] Some examples reported in the literature have provided evidence that magnetAbstract: Magnetic interactions in solid-state tantalum cluster compounds have been evidenced by using magnetic susceptibility measurements and corroborated by broken-symmetry DFT calculations.…”

Electron-Sink Behaviour of the Carbonylnickel Clusters [Ni32C6(CO)36]6– and [Ni38C6(CO)42]6–: Synthesis and Characterization of the Anions [Ni32C6(CO)36]n– (n = 5–10) and [Ni38C6(CO)42]n– (n = 5–9) and Crystal Structure of [PPh3Me]6[Ni32C6(CO)36] · 4 MeCN

“…EHMO [6,7b,8] as well stable on the timescale of cyclic voltammetry. as LDF [14] calculations suggest that the redox aptitude of some clusters descends from ad hoc electronic conditions Multivalent carbonyl metal clusters are of interest for such as the presence within the HOMO-LUMO gap of a several reasons. First of all, the knowledge of their structural parameters and/or spectroscopic behaviour can vali- [a] Diportimento di Chimica Fisida ed Inorganica, University of date their theoretical analysis (a procedure defined by L. the cation and the anion are organometallic clusters have to the parent [Ni 38 C 6 (CO) 42 ] 6Ϫ hexaanion, can probably be ascribed to the intrinsic acidity of the reaction solution owalready been prepared.…”

“…tive pairs of close-spaced one-electron reductions, as well as [Co 13 C 2 (CO) 30 ] nϪ (n ϭ 3, 4, 5, 6), [9,2c] [Co 9 Si(CO) 23 ] nϪ (n ϭ two close-spaced one-electron oxidations. Several of the 2, 3, 5), [10] [Ni 11 Bi 2 (CO) 18 ] nϪ (n ϭ 2, 3, 4), [11] above redox changes display features of electrochemical re-[Ni 13 Sb 2 (CO) 24 ] nϪ (n ϭ 2, 3, 4), [12] and [Fe 5 S 2 (CO) 14 ] nϪ versibility, even if most electrogenerated species are only (n ϭ 0, 1, 2), [13] in their cluster cores. EHMO [6,7b,8] as well stable on the timescale of cyclic voltammetry.…”

“…homo-, e.g. [Ir 14 (CO) 27 ] nϪ (n ϭ 0, 1, 2), [4] and heterometal-[Pt 19 (CO) 22 ] 4Ϫ , [15,2c] [Pt 24 (CO) 30 ] 2Ϫ , [16] and [HFe 6 Pd 6 -lic clusters, e.g. [Fe 3 Pt 3 (CO) 15 ] nϪ (n ϭ 0, 1, 2), [5,6] [Ag 13-(CO) 24 ] 3Ϫ [17] display a wider redox aptitude.…”