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An umbrella approach is described for vibrational frequency line shifts. This method has allowed for the efficient sampling of the solvent configurations corresponding to frequency shifts of a solute in mixed quantum-classical simulations.

A bathocuproine-coordinated palladium(O) complex that reacts with dioxygen to produce the eta2-peroxopalladium(II) species was reported. It was found that palladium-catalyzed oxidation reactions employ transition-metal cocatalysts or benzoquinone to circumvent an intrinsically slow, spin-forbidden reaction between Pd(O) and O2.

The mechanism of olefin substitution at palladium(0) is studied, and the results provide insights into the fundamental reactivity of electron-rich late transition metals. Density functional theory calculations of model alkene-substitution reactions at a dimine-palladium(0) center reveal that the palladium center reacts as a nucleophile via attack of metal-based lone pair on the empty pi* orbital of the incoming olefin.

This article focuses on spin forbidden reaction. Palladium-catalyzed reactions continue to emerge as effective methods for selective aerobic oxidation of organic molecules. These reactions often proceed by a two-stage "oxidase" mechanism and recently, a number of catalyst systems have been identified that undergo efficient dioxygen-coupled turnover in the absence of cocatalysts. DFF(UB3LYP) computations were used to characterize the reaction trajectory between 2 and triplet oxygen. Total energies, geometries, and charge distributions along the trajectory were obtained from relaxed potential energy scans.

Abstract: The novel PCP-pincer Pt(II) complex, has been prepared and characterized by 1H, 31P, and 13C NMR spectroscopy. The molecular structure of 1 has been determined through a single-crystal X-ray diffraction study. The pincer-ligated platinum complexes 1 and PtCl{C6H3-2,6-(CH2NEt2)2} (2) have been explored as catalysts for the hydroxylation of 1-propanol to 1,3-propanediol under mild conditions. Product ratios and turnover numbers achieved with both complexes compare favorably to those obtained with [PtCl4]2−. Moreover, the pincer complexes catalyze this transformation even upon replacement of PtCl4 by the more economical CuCl2 as the requisite stoichiometric oxidant. Analysis of the reaction mixture by 31P NMR spectroscopy following the hydroxylation of 1-propanol by 1 in the presence of CuCl2 revealed that 1 is partially converted to the ring substituted complex, . The molecular structure of 3 has been determined through a single-crystal X-ray diffraction study. [Copyright &y& Elsevier]

The effects of temperature and chemical environment on a pentanuclear cyanide-bridged, trigonal bipyramidal molecular paramagnet have been investigated. Using element- and oxidation state-specific near-ambient pressure X-ray photoemission spectroscopy (NAP-XPS) to probe charge transfer and second order, nonlinear vibrational spectroscopy, which is sensitive to symmetry changes based on charge (de)localization coupled with DFT, a detailed picture of environmental effects on charge-transfer-induced spin transitions is presented. The molecular cluster, Co 3 Fe 2 (tmphen) 6 (μ-CN) 6 ( t -CN) 6 , abbrev. Co 3 Fe 2 , shows changes in electronic behavior depending on the chemical environment. NAP-XPS shows that temperature changes induce a metal-to-metal charge transfer (MMCT) in Co 3 Fe 2 between a Co and Fe center, while cycling between ultrahigh vacuum and 2 mbar of water at constant temperature causes oxidation state changes not fully captured by the MMCT picture. Sum frequency generation vibrational spectroscopy (SFG-VS) probes the role of the cyanide ligand, which controls the electron (de)localization via the superexchange coupling. Spectral shifts and intensity changes indicate a change from a charge delocalized, Robin-Day class II/III high spin state to a charge-localized, class I low spin state consistent with DFT. In the presence of a H-bonding solvent, the complex adopts a localized electronic structure, while removal of the solvent delocalizes the charges and drives an MMCT. This change in Robin-Day classification of the complex as a function of chemical environment results in reversible switching of the dipole moment, analogous to molecular multiferroics. These results illustrate the important role of the chemical environment and solvation on underlying charge and spin transitions in this and related complexes.