@article{BaierKellingHoldt2015, author = {Baier, Heiko and Kelling, Alexandra and Holdt, Hans-J{\"u}rgen}, title = {PEPPSI-Effect on Suzuki-Miyaura Reactions Using 4,5-Dicyano-1,3-dimesitylimidazol-2-ylidene-Palladium Complexes: A Comparison between trans-Ligands}, series = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, journal = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, number = {11}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-1948}, doi = {10.1002/ejic.201500010}, pages = {1950 -- 1957}, year = {2015}, abstract = {The PEPPSI (Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation) complexes 12-15 with the structure [PdCl2{(CN)(2)IMes}(3-R-py)] (12: R = H; 13: R = Cl; 14: R = Br; 15: R = CN) bearing the maleonitrile-based N-heterocyclic carbene (NHC) (CN)(2)IMes ({(CN)(2)IMes}: 4,5-dicyano-1,3-dimesitylimidazol-2-ylidene) were prepared. Solid state structures of 14 and 15 were obtained. Complexes 14 and 15 adopt a slightly distorted square-planar coordination geometry in the solid state with the substituted pyridine ligand trans to the NHC. Catalytic activities of precatalysts 12-15 were studied and subsequently compared to complexes [PdCl2{(CN)(2)IMes}(PPh3)] (4) and [PdCl(dmba){(CN)(2)IMes}] (5) recently reported by our group in the Suzuki-Miyaura reaction of various aryl halides and phenylboronic acid. Reactions using previously reported [PdCl2(IMes)(py)] (IMes: 1,3-dimesitylimidazol-2-ylidene) (1) were also carried out and their results contrasted to those involving 12-15, 4 and 5. Differences in initiation rates and the catalytically active species related to the seven complexes in regards to the throw away ligand were investigated. Poisoning experiments with mercury show that palladium nanoparticles are responsible for the catalytic activity.}, language = {en} } @article{SengeDahmsHoldtetal.2015, author = {Senge, Mathias O. and Dahms, Katja and Holdt, Hans-J{\"u}rgen and Kelling, Alexandra}, title = {Porphyrin substituent regiochemistry, conformation and packing - the case of 5,10-diphenylporphyrin}, series = {Zeitschrift f{\"u}r Naturforschung : B, Chemical sciences}, volume = {70}, journal = {Zeitschrift f{\"u}r Naturforschung : B, Chemical sciences}, number = {2}, publisher = {De Gruyter}, address = {T{\"u}bingen}, issn = {0932-0776}, doi = {10.1515/znb-2014-0217}, pages = {119 -- 123}, year = {2015}, abstract = {5,10-Disubstituted porphyrins are more recent additions to the family of meso-substituted porphyrins. A crystallographic comparison of 5,10-diphenylporphyrin with the regioisomeric 5,15-disubstituted system reveals striking differences in their conformation. In the free base porphyrins the former uses mainly out-of-plane distortion to alleviate steric strain while in-plane core elongation predominates in the latter. In contrast, the structure of the Cu(II) complex is planar and forms strong p-p aggregates with very small lateral shifts. Macroscopically, the packing is similar to that of porphyrin sponges of the 5,10,15,20-tetraphenylporphyrin type.}, language = {en} } @article{SchmidtElizarovSchildeetal.2015, author = {Schmidt, Bernd and Elizarov, Nelli and Schilde, Uwe and Kelling, Alexandra}, title = {Dual Role of Acetanilides: Traceless Removal of a Directing Group through Deacetylation/Diazotation and Palladium-Catalyzed C-C-Coupling Reactions}, series = {The journal of organic chemistry}, volume = {80}, journal = {The journal of organic chemistry}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/acs.joc.5b00272}, pages = {4223 -- 4234}, year = {2015}, abstract = {The acetamide group enables regioselective oxidative ortho-C-H activation reactions, such as Pd-catalyzed acylation. The synthetic utility of these transformations can be significantly enhanced by using the acetamide as a quasi-leaving group in a subsequent conventional Pd-catalyzed coupling or cross-coupling reaction. The concept is illustrated herein for the synthesis of o-alkenyl- and o-arylphenones, which have potential for the synthesis of arylated aromatic heterocycles.}, language = {en} } @article{StrauchNeumannKellingetal.2015, author = {Strauch, Peter and Neumann, Mike and Kelling, Alexandra and Schilde, Uwe}, title = {Bis(1,2-dithiosquarato)nickelates(II): Synthesis, Structure, EPR and Thermal Behavior}, series = {Acta chimica Slovenica}, volume = {62}, journal = {Acta chimica Slovenica}, number = {2}, publisher = {Drustvo}, address = {Ljubljana}, issn = {1318-0207}, pages = {288 -- 296}, year = {2015}, abstract = {1,2-Dithiosquaratonickelates are available by direct synthesis from metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter cations. The synthesis and characterization, including mass spectrometry, of a series 1,2-dithiosquaratonickelates(II), [Ni(dtsq)(2)](2-), with several "onium" cations is reported and the X-ray structures of two diamagnetic complexes, (HexPh(3)P)(2)[Ni(dtsq)(2)] and (BuPh3P)(2)[Ni(dtsq)(2)] with sterically demanding counter ions are presented. The diamagnetic nickel complexes have been doped as host lattices with traces of Cu(II) to measure EPR for additional structural information. The thermal behavior of this series is studied by thermogravimetry and differential thermal analysis (TG/DTA). The thermolysis in air as well as under nitrogen atmosphere of these complexes results in nickel oxide nano-particles in all cases, which are characterized by X-ray powder diffraction.}, language = {en} } @article{MondalBehrensKellingetal.2015, author = {Mondal, Suvendu Sekhar and Behrens, Karsten and Kelling, Alexandra and Nabein, Hans-Peter and Schilde, Uwe and Holdt, Hans-J{\"u}rgen}, title = {Two Cd-II/Co-II-Imidazolate Coordination Polymers: Syntheses, Crystal Structures, Stabilities, and Luminescent/Magnetic Properties}, series = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie}, volume = {641}, journal = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie}, number = {11}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0044-2313}, doi = {10.1002/zaac.201500526}, pages = {1991 -- 1997}, year = {2015}, abstract = {Cadmium(II) based 2D coordination polymer [Cd(L1)(2)(DMF)(2)] (1) (L1 = 4,5-dicyano-2-methylimidazolate, DMF = N,N'-dimethylformamide) and 2D cobalt(II)-imidazolate framework [Co(L3)(4)] (2) (L3 = 4,5-diamide-2-ethoxyimidazolate) were synthesized under solvothermal reaction conditions. The materials were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction measurement (PXRD) and single-crystal X-ray diffraction. Compound 1 has hexacoordinate Cd-II ions and forms a zigzag chain-like coordination polymer structure, whereas compound 2 exhibits a 2D square grid type structure. The thermal stability analysis reveals that 2 showed an exceptional thermal stability up to 360 degrees C. Also, 2 maintained its fully crystalline integrity in boiling water as confirmed by PXRD. The solid state luminescent property of 1 was not observed at room temperature. Compound 2 showed an independent high spin central Co-II atom.}, language = {en} }