Multiple Additions of Phenylgermanium Ligands to Tetraruthenium and Tetraosmium Carbonyl Cluster Complexes

Three new compounds, Ru4(μ4-GePh)2(μ-GePh2)2(μ-CO)2(CO)8 (11), Ru4(μ4-GePh)2(μ-GePh2)3(μ-CO)(CO)8 (12), and Ru4(μ4-GePh)2(μ-GePh2)4(CO)8 (13), were obtained from the reaction of H4Ru4(CO)12 with excess Ph3GeH in octane (11 and 12) or decane (13) reflux. Compound 11 was converted to compound 13 by reaction with Ph3GeH by heating solutions in nonane solvent to reflux. Compounds 11−13 each contain a square-type arrangement of four Ru atoms capped on each side by a quadruply bridging GePh ligand to form an octahedral geometry for the Ru4Ge2 group. Compound 11 also contains two edge-bridging GePh2 groups on opposite sides of the cluster and two bridging carbonyl ligands. Compound 12 contains three edge-bridging GePh2 groups and one bridging carbonyl ligand. Compound 13 contains four bridging GePh2 groups, one on each edge of the Ru4 square. The reaction of H4Os4(CO)12 with excess Ph3GeH in decane at reflux yielded two new tetraosmium cluster complexes, Os4(μ4-GePh)2(μ-GePh2)3(μ-CO)(CO)8 (14) and Os4(μ4-GePh)2(μ-GePh2)4(CO)8 (15). These compounds are structurally similar to compounds 12 and 13, respectively

Toward less dependence on platinum group metal catalysts: the merits of utilizing tin

Minute stoichiometric bimetallic clusters rich in tin (PtSn2, RhSn2, and RuSn2) are powerful selective hydrogenation catalysts: these “molecular metallic” entities, supported on mesoporous silica and characterized by aberration-corrected electron microscopy, yield high percentages of cyclododecene (CDE) at fractional conversions ranging from 0.45 to 0.70 of the parent cyclododecatriene (CDT) at modest temperatures and under solvent-free conditions

High-Throughput Single-Molecule Spectroscopy Resolves the Conformational Isomers of BODIPY Chromophores

A borondipyrromethene (BODIPY) chromophore is connected to a benzoxazole, benzothiazole or nitrobenzothiazole heterocycle through an olefinic bridge with > trans configuration. Rotation about the two [C–C] bonds flanking the olefinic bridge occurs with fast kinetics in solution, leading to the equilibration of four conformational isomers for each compound. Ensemble spectroscopic measurements in solutions fail to distinguish the co-existing isomers. They reveal instead averaged absorption and emission bands with dependence of the latter on the excitation wavelength. Using high-throughput single-molecule spectroscopy, two main populations of single molecules with distinct spectral centroids are observed for each compound on glass substrates. Computational analyses suggest the two populations of molecules to be conformational isomers with antiperiplanar and periplanar arrangements of the BODIPY chromophores about its [C–C] bond to the olefinic bridge. Thus, statistical analysis of multiple single-molecule emission spectra can discriminate stereoisomers that would otherwise be impossible to distinguish by ensemble measurements alone