The microhydration of organic matter 1-3 deserves a systematic, unbiased comparison between theory and experiment . The primary and most fundamental quantities to be benchmarked are probably structure and energy of cold, neutral 1:1 hydrate complexes prepared in supersonic jet expansions . Any isomerism in the docking of individual water molecules to multifunctional organic molecules is of particular interest in this context, because theoretical input is most valuable and reliable for trends and comparisons . This is where systematic model errors often tend to cancel for good reasons , paving the way for helpful approximations. The properties of monoisomeric systems are valuable for a first calibration of absolute quantities, which are typically more challenging because they require highly accurate treatments of electronic structure and nuclear dynamics effects. It is rewarding that there are numerous rotational spectroscopy studies of monohydrates with more or less direct structural and sometimes relative energy information available in the literature . These provide a lot of detail on the shallow potential energy landscapes of solvation phenomena.