The tungsten(IV) complex (Et4N)2[W(O)(mnt)2] (1; mnt = maleonitriledithiolate) was proposed (Sarkar et al., J. Am. Chem. Soc. 1997, 119, 4315) to be a functional analogue of the active center of the enzyme acetylene hydratase from Pelobacter acetylenicus, which hydrates acetylene (ethyne; 2) to acetaldehyde (ethanal; 3). In the absence of a satisfactory mechanistic proposal for the hydration reaction, we considered the possibility of a metal–vinylidene type activation mode, as it is well established for ruthenium-based alkyne hydration catalysts with anti-Markovnikov regioselectivity. To validate the hypothesis, the regioselectivity of tungsten-catalyzed alkyne hydration of a terminal, higher alkyne had to be determined. However, complex 1 was not a competent catalyst for the hydration of 1-octyne under the conditions tested. Furthermore, we could not observe the earlier reported hydration activity of complex 1 towards acetylene. A critical assessment of, and a possible explanation for the earlier reported results are offered. The title question is answered with "no".

A HOT‐CAT (homogeneous thermal catalysis) screen using microwave‐heating and quantitative NMR (qNMR) analysis has been developed for identification and comparison of catalyst activity in homogeneous metal‐based catalysis. The hydration of terminal alkynes to ketones or aldehydes served as a model reaction in this proof‐of‐concept study. Key aspects of the screen are the use of a high‐temperature setting (e. g., 160 °C) at a fixed, short reaction time (e. g., 15 min) for all samples. Analysis of crude reaction mixtures by a standardized, quantitative 1H NMR protocol gives a comprehensive picture of catalyst chemo‐ and regioselectivity, which permits broad comparisons and the discovery of non‐target reactivity. For catalytic alkyne hydration, data for 105 runs involving 81 catalyst systems with 15 different metals is presented. The activity of all established catalyst systems was reproduced, and new catalyst systems with Markovnikov hydration selectivity were discovered and applied to preparative runs, namely Cu2O−CSA (CSA=camphorsulfonic acid), Co(OAc)2−tetraphenylporphyrin−CSA and [IrCl(COD)]−CSA.