No abstract

Titanium containing aminoterephthalate metal organic framework promotes the photocatalytic overall water splitting into H2 and O2 at a rate that depends on the presence of Pt, RuO2 and CoOx co-catalyst. The best values of have been obtained for the MIL-125-NH2 material that contains Pt and RuO2, reaching a production of 218 and 85 µmol/g photocatalyst -1 at 24 h for H2 and O2, respectively.

The assumption that oxidative addition is the key step during the cross-coupling reaction of aryl halides has led to the development of a plethora of increasingly complex metal catalysts, obviating in many cases the exact influence of the base, the simplest, inexpensive and necessary reagent for this paramount transformation. Here, a combined experimental and computational study shows that the oxidative addition is not any more the controlling step during different cross-coupling reactions if catalyzed by ligand-free sub-nanometer Pd or Pt clusters, translating reactivity control to subtle changes in the base, i.e. acetate drives to the Heck, carbonate to the Sonogahira and phosphate to the Suzuki reaction. For that, the exposed metal atoms in the cluster cooperate to enable an extremely easy oxidative addition of the aryl halide, even chlorides, and allows the base to bifurcate the coupling. This base-controlled orthogonal reactivity with ligand-free catalysts open new avenues in the design of cross-coupling reactions in organic synthesis.