Additional Investigations of a New Kinetic Method To Follow Transition-Metal Nanocluster Formation, Including the Discovery of Heterolytic Hydrogen Activation in Nanocluster Nucleation Reactions

Abstract

A few years ago we developed a new kinetic method for following transition-metal nanocluster formation in which the resultant nanocluster's catalytic activity was used as a reporter reaction via the pseudoelementary step concept. This method in turn yielded insights into a new, broadly applicable mechanism of nanocluster formation under H2 consisting of (a) slow, continuous nucleation, A → B, followed by (b) fast autocatalytic surface growth, A + B → 2B (A = the nanocluster precursor, [Bu4N]5Na3[(1,5-COD)Ir·P2W15Nb3O62], B = the resultant nanocluster's surface metal atoms), in which the nanocluster behaves as a “living metal polymer”. Herein, this new kinetic method is investigated and tested further: (i) by following the Ir(0)∼300 nanocluster's kinetics of formation more directly via the H2 uptake reaction of the [Bu4N]5Na3[(1,5-COD)Ir·P2W15Nb3O62] precursordoes this also show an autocatalytic H2 uptake curve?; (ii) by seeing if the predicted initially small, then larger (past the induction period) size...