Finally, we explored the monodentate and bidentate complexes as catalysts in the transfer hydrogenation of acetophenone to 1-phenylethanol. We hypothesised that the azophosphine could act as a hybrid ligand to enable this process to occur in a base-free manner. To this end, the base-free transfer hydrogenation of acetophenone using isopropanol as a hydrogen source was carried out using 1 mol% of 4-OMe or 5-OMe as catalyst (Figure ), and the reactions followed by FTIR spectroscopy using ReactIR. ReactIR allows for in situ monitoring of reactant and/or product, without the need for offline analysis. The use of standard addition (see SI) enabled quantification of acetophenone concentration and calculation of its conversion by following the isolated, characteristic peak at 1267 cm -1 (C-C(O)-C stretch). As the peaks in the FTIR spectra assigned to 1-phenylethanol were not sufficiently resolved, reliable quantification of product yield was not possible by this method. H NMR spectroscopy instead provided an integration ratio of acetophenone:1-phenylethanol in the reaction mixture to provide their relative % composition. Note this value does not equate to a % yield of 1-phenylethanol as it assumes selective conversion of acetophenone, although no other sideproducts were observed in the 1 H NMR spectra. When using the monodentate 4-OMe as the catalyst the reaction was sluggish, although it is noteworthy that some of the target 1-phenylethanol was observed despite the lack of external base in this reaction. The FTIR reaction monitoring for this reaction reproducibly showed erratic spikes in the spectra at various timepoints, which precludes any detailed discussion of kinetics, but after 5 hours approximately 16% of the acetophenone had been converted. An aliquot of the reaction mixture taken after 16 hours was analysed by 1 H NMR spectroscopy and showed a 79:21 ratio of acetophenone:1-phenylethanol. The experiment using the bidentate 5-OMe as the catalyst was far more promising. The surface plot of 5-OMe showed the consumption of acetophenone, represented by the decrease in the peak at 1681 cm -1 (C=O stretch, acetophenone) and the tracked peak at 1267 cm -1 with time (Figure ). The production of acetone as a by-product immediately after addition of 5-OMe was observed, represented by the characteristic peak at 1710 cm -1 (C=O stretch). After 5 hours, the conversion of acetophenone was 67%. H NMR spectroscopic analysis after 16 hours showed a relative composition of 11% acetophenone to 89% 1phenylethanol. These results provide a proof-ofconcept that the azophosphine ligand is capable of promoting the base-free transfer hydrogenation of acetophenone, and that the bidentate complex 5-OMe is a more active catalyst than the monodentate 4-OMe.