Electron Transport through Linear-, Broken-, and Cross-Conjugated Polycyclic Compounds.

Quantum interference (QI) effects offer unique opportunities to modulate charge transport through single molecules. In recent years, several transmission selection rules have been developed to determine constructive and destructive QIs in an intuitive and simple manner, although some of these rules fail for cross-conjugated systems. In this work, we evaluate the performance of distinct transmission rules on a broad series of anthracene and fluorene derivatives with distinctive structural features including linear-, broken-, and cross-conjugation, heteroatoms, and five-membered rings as such species affords a predictive challenge for the qualitative selection rules for QI effects.

Similarities and Differences in Benzene Reduction with Ca, Sr, Yb and Sm: Strong Evidence for Tetra-Anionic Benzene.

Inverse sandwich complexes of Yb and Sm stabilized by a bulky β-diketiminate (BDI) ligand have been prepared: (BDI)Ln(η,η-CH)Ln(BDI); Ln=lanthanide. Coordinated benzene ligands can be neutral, di-anionic or, often controversially discussed, even tetra-anionic. The formal charge on benzene is correlated to assignment of the metal oxidation state which generally poses a problem.

T-Shaped Palladium and Platinum {MNO} Nitrosyl Complexes.

The synthesis and characterization of a homologous series of T-shaped {MNO} nitrosyl complexes of the form [M(PR)(NO)] (M = Pd, Pt; R = Bu, Ad) are reported. These diamagnetic nitrosyls are obtained from monovalent or zerovalent precursors by treatment with NO and NO, respectively, and are notable for distinctly bent M-NO angles of ∼123° in the solid state. Adoption of this coordination mode in solution is also supported by the analysis of isotopically enriched samples by N NMR spectroscopy.

Modulation of Metal Carbonyl Stretching Frequencies in the Second Coordination Sphere through the Internal Stark Effect.

Spectroscopic and computational examination of a homologous series of rhodium(I) pybox carbonyl complexes has revealed a correlation between the conformation of the flanking aryl-substituted oxazoline donors and the carbonyl stretching frequency. This relationship is also observed experimentally for octahedral rhodium(III) and ruthenium(II) variants and cannot be explained through the classical, Dewar-Chatt-Duncanson, interpretation of metal-carbonyl bonding. Instead, these findings are reconciled by local changes in the magnitude of the electric field that is projected along the metal-carbonyl vector: the internal Stark effect.