Ma Teresa Pereira

Bio: Ma Teresa Pereira is an academic researcher from University of Santiago de Compostela. The author has contributed to research in topics: Diphosphines & Palladium. The author has an hindex of 16, co-authored 34 publications receiving 709 citations. Previous affiliations of Ma Teresa Pereira include University of Santiago, Chile.

Formation, characterization, and structural studies of novel thiosemicarbazone palladium(II) complexes. Crystal structures of [{Pd[C6H4C(Et)NNC(S)NH2]}4], [Pd{C6H4C(Et)NN C(S)NH2}(PMePh2)] and [{Pd[C6H4C(Et)NNC(S)NH2]}2(µ-Ph2PCH2PPh2)]

Abstract: The reaction of thiosemicarbazones 4-MeC6H4C(Me)NN(H)C(S)NH2 a, C6H5C(Et)NN(H)C(S)NH2 b and 4-MeC6H4C(Me)NN(H)C(S)NHMe c with K2[PdCl4] led to tetranuclear palladium(II) compounds, [{Pd[4-MeC6H3C(Me)NNC(S)NH2]}4], 1a, [{Pd[C6H4C(Et)NNC(S)NH2]}4] 1b, and [{Pd[4-MeC6H3C(Me) NNC(S)NHMe]}4] 1c; the ligands are tridentate through the [C, N, S] atoms and they are deprotonated at the NH group. The Pd–Schelating bond is sufficiently strong for the complexes to undergo reactions with nucleophiles without bond cleavage. The molecular structure of 1b has been determined by single-crystal diffraction, confirming the formation of the tetranuclear moieties. Hydrogen bonding N· · ·H and S· · ·H links Pd4 clusters into strands in the solid state. Reaction of 1a and 1b with phosphines gave mono- and di-nuclear species, 2a, 2b, 3b and 5a, 5b, respectively. Treatment with 1,1′-bis(diphenylphosphino)ferrocene led to trimetallic compounds 6a and 6b. The molecular structure of 3b has been determined by X-ray crystallography; dimer units are present through N· · ·H hydrogen bonds. The reaction of 2b with hydrochloric acid resulted in a 1∶1 electrolyte, 4b, with NH and CS groups. Alternatively, treatment of 1a, 1b and 1c with strong chelating phosphines produced mononuclear compounds with only cleavage of the Pd–Sbridging bonds, 7a, 7b, 7c and 8c with the diphosphine monodentate; 7a and 7b were obtained with the dinuclear species 7a′ and 7b′, respectively, as impurities, where the bidentate phosphine ligand bridges two metallated units. The crystal structure of one such compound, 7b′, with a bridging bis(diphenylphosphino)methane ligand, is also described.

“Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects

Abstract: “Rollover” cyclometalation constitutes a special case among the well-known class of cyclometalation reactions. An overview is given that covers the very first description of this reaction type, as well as recent developments. In addition, not only condensed-phase experiments are reviewed, but also investigations based on mass spectrometric techniques, together with “in silico” studies using DFT-based calculations are considered. While the latter two methods allow for a detailed analysis of the intrinsic factors that affect the reaction mechanisms, consideration of all three regimes permits to develop a coherent mechanistic picture and to address the often noted gap between condensed- and gas-phase studies. Moreover, the quite unexpected reactivity of “rollover” cyclometalated complexes in gas-phase experiments, as well as potential applications, e.g. in synthetic procedures, are discussed in some detail.