Ferromagnetic Coupling in Hexanuclear Gadolinium Clusters

Abstract

The magnetic susceptibilities of hexanuclear gadolinium clusters in the compounds Gd(Gd6ZI12) (Z = Co, Fe, or Mn) and CsGd(Gd6CoI12)2 are reported and subjected to theoretical analysis with the help of density functional theory (DFT) computations. The single-crystal structure of Gd(Gd6CoI12) is reported here as well. We find that the compound with a closed shell of cluster bonding electrons, Gd(Gd6CoI12), exhibits the effects of antiferromagnetic coupling over the entire range of temperatures measured (4-300 K). Clusters with unpaired, delocalized cluster bonding electrons (CBEs) exhibit enhanced susceptibilities consistent with strong ferromagnetic coupling, except at lower temperatures (less than 30 K) where intercluster antiferromagnetic coupling suppresses the susceptibilities. The presence of two unpaired CBEs, as in [Gd6MnI12]3-, yields stronger coupling than when just one unpaired CBE is present, as in [Gd6FeI12]3- or [Gd6CoI12]2-. DFT calculations on model molecular systems, [Gd6CoI12](OPH3)6 and [Gd6CoI12]2(OPH3)10, indicate that the delocalized cluster bonding electrons are highly effective at mediating intracluster ferromagnetic exchange coupling between the Gd atom 4f7 moments and that intercluster coupling is expected to be antiferromagnetic. The DFT calculations were used to calculate the relative energies of various 4f7 spin patterns and form the basis for construction of a simple spin Hamiltonian describing the coupling within the [Gd6CoI12] cluster.

Gd26Cluster Consisting of Distorted Cubane Cores: Synthesis, Structure and Heterogeneous Catalytic Epoxidation of Olefins

“…In this context, oxo, hydroxo and fluorido bridged lanthanide clusters are worthy of note. [24][25][26][27][28][29][30][31] It has been well documented that lanthanide compounds have relevance to homogeneous catalysis, [32] molecule-based magnetic materials, [33] contrast agents for magnetic resonance imaging [34] and fixation media for essential atmospheric gases. [35] In the field of oxidative catalytic transformations, [36] epoxidation of alkenes is a key chemical process in biology, [37] synthetic organic chemistry and in chemical industry.…”

Endohedral Stannaspherenes Mn@Sn12 and its Dimer: Ferromagnetic or Antiferromagnetic?

“…Observe that the V-[Mn@Sn 12 ] 2 isomer is predicted to be a metastable dimer, while both the E- Sn 12 superexchange coupling is effectively precluded. [35] Consequently, we consider the magnetic exchange coupling of the two magnetic Mn centers. In particular, we focus on the ferromagnetic state (FS), where all the ten 3d electrons (five per each Mn 2 + ) are spin parallel and the antiferromagnetic state (AS) in which all five electrons of one manganese cation are spin up and all five on the other manganese cation are spin down.…”

Revealing Tendencies in the Electronic Structures of Polar Intermetallic Compounds

“…The amounts of cluster-based electrons (CBEs) are usually obtained by subtracting the numbers of halide ligands from the net valence electron counts of the transition-metal centered rare-earth metal cluster [45]. For instance, applying this scheme to formally distribute electrons in the previously reported Y7I12Co yields a total of 18 CBEs (=7•3 + 9 -12), which is expected to correspond to (preferable) closed-shell configurations for the [TR6]X12R-type compounds [51][52][53]. Further research on the electronic structures of transition-metal centered rare-earth metal cluster halides crystallizing with the [TR6]X10-type whose crystal structure also comprises isolated octahedral [TR6] clusters as observed for the [TR6]X12R-type ( Figure 1) revealed that closed-shell configurations are also achieved The amounts of cluster-based electrons (CBEs) are usually obtained by subtracting the numbers of halide ligands from the net valence electron counts of the transition-metal centered rare-earth metal cluster [45].…”

“…Further research on the electronic structures of transition-metal centered rare-earth metal cluster halides crystallizing with the [TR6]X10-type whose crystal structure also comprises isolated octahedral [TR6] clusters as observed for the [TR6]X12R-type ( Figure 1) revealed that closed-shell configurations are also achieved The amounts of cluster-based electrons (CBEs) are usually obtained by subtracting the numbers of halide ligands from the net valence electron counts of the transition-metal centered rare-earth metal cluster [45]. For instance, applying this scheme to formally distribute electrons in the previously reported Y 7 I 12 Co yields a total of 18 CBEs (=7·3 + 9 -12), which is expected to correspond to (preferable) closed-shell configurations for the [TR 6 ]X 12 R-type compounds [51][52][53]. Further research on the electronic structures of transition-metal centered rare-earth metal cluster halides crystallizing with the [TR 6 ]X 10 -type whose crystal structure also comprises isolated octahedral [TR 6 ] clusters as observed for the [TR 6 ]X 12 R-type ( Figure 1) revealed that closed-shell configurations are also achieved for a total of 18 CBEs (an overview about the [TR 6 ]X 12 R-type as well as [TR 6 ]X 10 -type halides identified to date has been provided elsewhere [54]).…”