Although nanoparticles are widely used as catalysts, little is knownabout their potential ability to trigger privileged transformations as compared to homogeneous molecular or bulk heterogeneous catalysts.W eh erein demonstrate (and rationalize) that nanoparticles displayorthogonal reactivity to molecular catalysts in the cross-coupling of aryl halides with aryl germanes.W hile the aryl germanes are unreactive in L n Pd 0 /L n Pd II catalysis and allowselective functionalization of established coupling partners in their presence,t hey display superior reactivity under Pd nanoparticle conditions,o utcompeting established coupling partners (such as ArBPin and ArBMIDA) and allowing air-tolerant, base-free,a nd orthogonal access to valuable and challenging biaryl motifs.A s opposed to the notoriously unstable polyfluoroaryl-and 2-pyridylboronic acids,the corresponding germanes are highly stable and readily coupled. Our mechanistic and computational studies provideu nambiguous support of nanoparticle catalysis and suggest that owingtothe electron richness of aryl germanes,t hey preferentially react by electrophilic aromatic substitution, and in turn are preferentially activated by the more electrophilic nanoparticles.

This report widens the repertoire of emerging Pd catalysis to carbon-heteroatom, that is, C-S bond formation. While Pd -catalyzed protocols may suffer from the formation of poisonous sulfide-bound off-cycle intermediates and lack of selectivity, the mechanistically diverse Pd catalysis concept circumvents these challenges and allows for C-S bond formation (S-aryl and S-alkyl) of a wide range of aryl halides. Site-selective thiolations of C-Br sites in the presence of C-Cl and C-OTf were achieved in a general and a priori predictable fashion. Computational, spectroscopic, X-ray, and reactivity data support dinuclear Pd catalysis to be operative. Contrary to air-sensitive Pd , the active Pd species was easily recovered in the open atmosphere and subjected to multiple rounds of recycling.

The transmetalation is a key elementary step in cross-coupling reactions. Yet, the precise nature of its mechanism and transition state geometry are frequently elusive. This report discloses our study of the transmetalation of [Pd ]-F complexes with the silane- and stannane-based trifluoromethylation agents, R SiCF and R SnCF . A divergent reactivity was uncovered, with the stannane showing selective R-group transfer, and the silane selective CF -group transfer. Using a combined experimental and computational approach, we uncovered a hitherto unrecognized transmetalation mechanism with the widely employed R SiCF reagent, explaining its unique activity in metal-catalyzed trifluoromethylations. While the stannane reacts via a cyclic, 4-membered transition state, the silane undergoes a fundamentally different pathway and releases a difluorocarbene in the transmetalation event. Molecular dynamics studies clearly reinforced the liberation of a free CF carbene, which reacts with [Pd ]-F to ultimately generate [Pd ]-CF

Although nanoparticles are widely used as catalysts, little is knownabout their potential ability to trigger privileged transformations as compared to homogeneous molecular or bulk heterogeneous catalysts.W eh erein demonstrate (and rationalize) that nanoparticles displayorthogonal reactivity to molecular catalysts in the cross-coupling of aryl halides with aryl germanes.W hile the aryl germanes are unreactive in L n Pd 0 /L n Pd II catalysis and allowselective functionalization of established coupling partners in their presence,t hey display superior reactivity under Pd nanoparticle conditions,o utcompeting established coupling partners (such as ArBPin and ArBMIDA) and allowing air-tolerant, base-free,a nd orthogonal access to valuable and challenging biaryl motifs.A s opposed to the notoriously unstable polyfluoroaryl-and 2-pyridylboronic acids,the corresponding germanes are highly stable and readily coupled. Our mechanistic and computational studies provideu nambiguous support of nanoparticle catalysis and suggest that owingtothe electron richness of aryl germanes,t hey preferentially react by electrophilic aromatic substitution, and in turn are preferentially activated by the more electrophilic nanoparticles.

We synthesize heterofluorene monomers with Si, Ge, N, As, Se, and Te occupying the 9-position of the fluorene motif, which are then polymerized by Suzuki coupling. The optical properties of the obtained polymers are investigated in their solid state. We compare and elucidate effects in the materials absorption, emission, quantum yield (Φ), and fluorescence lifetime. Moreover, we determine the refractive indices n and absorption coefficient k by variable angle spectroscopic ellipsometry (VASE). We show that in addition to already known C, Si, and N containing polyfluorenes also Ge and As containing polymers exhibit amplified spontaneous emission.