Cluster carbonyls of the [Re6(μ3-Se)8]2+ core: synthesis, structural characterization, and computational analysis

Abstract

The reactions of the previously reported cluster complexes [Re(6)(mu(3)-Se)(8)(PEt(3))(5)I]I, trans-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)I(2)], and cis-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)I(2)] with the [Re(6)(mu(3)-Se)(8)](2+) core with CO in the presence of AgSbF(6) afforded the corresponding cluster carbonyls [Re(6)(mu(3)-Se)(8)(PEt(3))(5)(CO)][SbF(6)](2) (), trans-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)(CO)(2)][SbF(6)](2) (), and cis-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)(CO)(2)][SbF(6)](2) (). Infrared spectroscopy indicated weakening of the bond in CO, suggesting the existence of backbonding between the cluster core and the CO ligand(s). Electrochemical studies focusing on the reversible, one-electron oxidation of the cluster core revealed a large increase in the oxidation potential upon going from the acetonitrile derivatives to their carbonyl analogs, consistent with the depleted electron density of the cluster core upon CO ligation. Disparities between the IR spectra and oxidation potential between and indicate that electronic differences exist between sites trans and cis to the location of a ligand of interest. The active role played by the Se atoms in influencing the cluster-to-CO bonding interactions is suggested through this result and density functional (DF) computational analysis. The computations indicate that molecular orbitals near the HOMO account for backbonding interactions with a high percentage of participation of Se orbitals.

The Cluster [Re6Se8I6]3− Induces Low Hemolysis of Human Erythrocytes in Vitro: Protective Effect of Albumin

“…TBA (tetrabutyl ammonium) salt of the octahedral hexarhenium(III) (one of the 6 Re is actually Re(IV)) chalcogenide cluster complex, Re 6 Se 8 I 6 3 − cluster, was prepared and purified according to procedures reported elsewhere [1,18,19]. A stock solution of the cluster in DMSO at 100 mM was prepared and used within the day.…”

Redox Potential and Crystal Chemistry of Hexanuclear Cluster Compounds

“…The values of the redox potentials are taken from refs. [ 5 , 10 , 24 , 25 ]. The electrochemical experiments were performed in CH 3 CN or CH 2 Cl 2 solutions.…”

A Theoretical Study of the Binding of [Re6Se8(OH)2(H2O)4] Rhenium Clusters to DNA Purine Base Guanine

“…The results of the full geometric optimization computations by the DFT method at ZORA-PW91-COSMO [25,26,27,28] level are appropriate for this system, and on the basis of the computed geometries of the complexes, we can conduct a structural analysis of the binding between the hydrated rhenium species to DNA model bases at higher basis set level [22,29,30]. Since there are no yet reported measurements of the Guanine cluster interactions, our results reported here may have a predictive character.…”