@article{GoettelGaoDotzaueretal.2020, author = {Goettel, James T. and Gao, Haopeng and Dotzauer, Simon and Braunschweig, Holger}, title = {\(^{Me}\)CAAC=N\(^{-}\): A Cyclic (Alkyl)(Amino)Carbene Imino Ligand}, series = {Chemistry - A European Journal}, volume = {26}, journal = {Chemistry - A European Journal}, number = {5}, doi = {10.1002/chem.201904715}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212662}, pages = {1136-1143}, year = {2020}, abstract = {A cyclic (alkyl)(amino)carbene (CAAC) has been shown to react with a covalent azide similar to the Staudinger reaction. The reaction of \(^{Me}\)CAAC with trimethylsilyl azide afforded the N-silylated 2-iminopyrrolidine (\(^{Me}\)CAAC=NSiMe\(_{3}\)), which was fully characterized. This compound undergoes hydrolysis to afford the 2-iminopyrrolidine and trimethylsiloxane which co-crystallize as a hydrogen-bonded adduct. The N-silylated 2-iminopyrrolidine was used to transfer the novel pyrrolidine-2-iminato ligand onto both main-group and transition-metal centers. The reaction of the tetrabromodiborane bis(dimethyl sulfide) adduct with two equivalents of \(^{Me}\)CAAC=NSiMe\(_{3}\) afforded the disubstituted diborane. The reaction of \(^{Me}\)CAAC=NSiMe\(_{3}\) with TiCl\(_{4}\) and CpTiCl\(_{3}\) afforded \(^{Me}\)CAAC=NTiCl\(_{3}\) and \(^{Me}\)CAAC=NTiCl\(_{2}\)Cp, respectively.}, language = {en} } @article{EstrechoGaoBrodbecketal.2016, author = {Estrecho, E. and Gao, T. and Brodbeck, S. and Kamp, M. and Schneider, C. and H{\"o}fling, S. and Truscott, A. G. and Ostrovskaya, E. A.}, title = {Visualising Berry phase and diabolical points in a quantum exciton-polariton billiard}, series = {Scientific Reports}, volume = {6}, journal = {Scientific Reports}, number = {37653}, doi = {10.1038/srep37653}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167496}, year = {2016}, abstract = {Diabolical points (spectral degeneracies) can naturally occur in spectra of two-dimensional quantum systems and classical wave resonators due to simple symmetries. Geometric Berry phase is associated with these spectral degeneracies. Here, we demonstrate a diabolical point and the corresponding Berry phase in the spectrum of hybrid light-matter quasiparticles—exciton-polaritons in semiconductor microcavities. It is well known that sufficiently strong optical pumping can drive exciton-polaritons to quantum degeneracy, whereby they form a macroscopically populated quantum coherent state similar to a Bose-Einstein condensate. By pumping a microcavity with a spatially structured light beam, we create a two-dimensional quantum billiard for the exciton-polariton condensate and demonstrate a diabolical point in the spectrum of the billiard eigenstates. The fully reconfigurable geometry of the potential walls controlled by the optical pump enables a striking experimental visualization of the Berry phase associated with the diabolical point. The Berry phase is observed and measured by direct imaging of the macroscopic exciton-polariton probability densities.}, language = {en} }