Always There Where the Science Is.

Physical chemistry is everywhere! Over the past two decades, ChemPhysChem has accompanied many of the major developments in physical chemistry and chemical physics, filing its pages with exciting new science. In this Editorial, we look at some of the highlights during this time, focusing on our activities and achievements in 2021, and peek at what we have in stock for the next year.

New Sensation.

New Sensation: ChemPhysChem has been going strong for just over 20 years now. On April 1 2020, we took on a modern new look, abandoning the blue framed cover that was an integral part of ChemPhysChem's identity, together with our whole Chemistry Europe journal family.

First and second proton affinities of carbon bases.

Quantum chemical calculations at the MP2/TZVPP//BP86/SVP level are reported for the first and second proton affinities (PAs) of divalent carbon-donor molecules. The molecules investigated are imidazol-2-ylidenes ("normal" NHCs) and the tautomeric imidazol-4/5-ylidenes ("abnormal" NHCs). PAs are also calculated for acyclic and cyclic carbodiphosphoranes, carbophosphoranesulfide, unsaturated and saturated carbodicarbenes, tetraaminoallenes and carbon suboxide.

Bonding analysis of N-heterocyclic carbene tautomers and phosphine ligands in transition-metal complexes: a theoretical study.

DFT calculations at the BP86/TZ2P level were carried out to analyze quantitatively the metal-ligand bonding in transition-metal complexes that contain imidazole (IMID), imidazol-2-ylidene (nNHC), or imidazol-4-ylidene (aNHC). The calculated complexes are [Cl4TM(L)] (TM = Ti, Zr, Hf), [(CO)5TM(L)] (TM = Cr, Mo, W), [(CO)4TM(L)] (TM = Fe, Ru, Os), and [ClTM(L)] (TM = Cu, Ag, Au). The relative energies of the free ligands increase in the order IMID < nNHC < aNHC.