A variety of compounds and their intermediates may be produced via catalysis, which is basically a sustainable process. The disadvantage of base-metal catalysts (and generally complexes with adjacent spin states) is that they frequently exhibit O2 sensitivity; in contrast, precious-metal complexes exhibit slower O2 reactions and higher resilience. Although air sensitivity complicates reactions further, air removal is a comparatively simple operation. The use of air-stable halide or carboxylate complexes that are transformed into the active catalyst under catalytic conditions is one method that this issue has been handled.