Upgrade of Weak σ-Hole Bond Donors via Cr(CO) Complexation.

Molecular recognition mediated by σ-hole interactions is enhanced as the electrostatic potential at the σ-hole becomes increasingly positive. Traditional methods to strengthen σ-hole donor ability of atoms such as halogens often involve covalent modifications, such as, introducing electron-withdrawing substituents (neutral or positively charged) or electrochemical oxidation. Metal coordination, a relatively underexplored approach, offers a promising alternative.

Flipping the Metalation of 4-Dimethylaminopyridine: Steric Repulsion versus London Dispersion Attraction.

Non-covalent interactions, including the coordination of an organolithium reagent by a directing group and the steric hindrance from substituents, play a crucial role in determining the selectivity of metalation reactions. Here, we demonstrate the effective utilization of steric interactions for flipping the lithiation of 4-dimethylaminopyridine (DMAP). Introduction of a MeSi substituent to the position 1 of DMAP or simple complexation with t-BuLi allows selective C3-lithiation, due to the steric hindrance of a C2-H bond by the bulky moiety at the pyridine nitrogen.

Phosphine selenides: versatile NMR probes for analyzing hydrogen OH⋯Se and halogen I⋯Se bonds.

Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for studying the structure and dynamics of various non-covalent interactions. However, often spectral parameters that are applicable for estimation of parameters of one type of non-covalent interaction will be inapplicable for another. Therefore, researchers are compelled to use spectral parameters that are specifically tailored to the type of non-covalent interaction being studied.

Aggregation Game: Changing Solid-State Emission Using Different Counterions in Monoalkynylphosphonium Pt(II) Complexes.

Two series of heteroleptic monoalkynylphosphonium Pt(II) complexes decorated with 2,2':6',2''-terpyridine (, series) and 6-phenyl-2,2'-bipyridine (, series) ligands, were prepared and characterized by spectroscopic methods. The complexes obtained exhibit triplet emission in solution, and the characteristics inside the series depend on the nature of the alkynylphosphonium ligand. The description of electronic transitions responsible for energy absorption and emission in discrete Pt(II) complexes was made on the basis of a detailed analysis of the results of DFT calculations, and has shown to involve MLCT, ILCT, and LLCT transitions.