Han Vinh Huynh

Publications (48) View all

• Article: Electronic structural trends in divalent carbon compounds.

  Han Vinh Huynh, Gilles Frison
  [show abstract] [hide abstract]
  ABSTRACT: This work aims to analyze and compare the intrinsic electronic densities in a series of neutral and anionic divalent carbon-donor derivatives. The σ-lone pair at the divalent carbon is the HOMO of these species. Structural factors have been identified that influence its energy, which is a measure of the σ-basicity. The π-electronic structure has been described as a function of the π-population. Our results show that no straightforward structural criteria correlate with the π-electronic distribution. However, the π-population, as well as the π-acidity and π-basicity, are related to the π-MOs. In all cases these π-MOs can be qualitatively obtained based on those of the protonated analogues by simply increasing the energy of the p(π) orbital at the divalent carbon atom compared to normal sp(2) carbon. Such an analysis allows a rationalization of the trends observed for the π-electronic structure of these ligands. Notably, this explains the values of the π-population at the divalent carbon center, which shows an increasing and continuous range from classical NHCs to mesoionic "carbenes".
  The Journal of Organic Chemistry 12/2012; · 4.45 Impact Factor
• Article: Highly modular access to functionalised metal-carbenes via post-modifications of a single bromoalkyl-substituted NHC-Pd(ii) complex.

  Han Vinh Huynh, Qiaoqiao Teng
  [show abstract] [hide abstract]
  ABSTRACT: The synthesis of a bromopropyl-substituted NHC-Pd(ii) complex, which can undergo exemplary and versatile 2nd and 3rd generation post-modifications easily affording 7 new functionalised NHC complexes, is demonstrated.
  Chemical Communications 08/2012; · 6.17 Impact Factor
• Source

  Available from: Han Vinh Huynh

  Article: Pyrazolin-5-ylidene Palladium(II) Complexes: Synthesis, Characterization, and Application in the Direct Arylation of Pentafluorobenzene

  Jan Christopher Bernhammer, Han Vinh Huynh
  [show abstract] [hide abstract]
  ABSTRACT: Ten palladium(II) complexes bearing a pyrazolin-5-ylidene ligand have been synthesized by oxidative addition and silver carbene transfer pathways. The weakly bound acetonitrile ligand in the initially obtained trans-[PdBr2(MeCN)(Pyry)] complex (6, Pyry = 1-phenyl-2,3-dimethylpyr-11 azolin-5-ylidene) could be replaced by other donor ligands, and additional NHC ligands were introduced either by silver carbene transfer reactions or via reaction with in situ generated free carbenes. Using our previously reported 13C NMR-based electronic parameter, the pyrazolin-5-ylidene ligand is estimated to be among the most strongly donating ligands on our scale so far. The complexes obtained were employed as catalysts for the direct arylation of pentafluorobenzene with moderate to good yields under optimized conditions.
  Organometallics 06/2012; 31(14):5121. · 3.96 Impact Factor
• Source

  Available from: Han Vinh Huynh

  Article: Correlation of spectroscopically determined ligand donor strength and nucleophilicity of substituted pyrazoles.

  Jan Christopher Bernhammer, Han Vinh Huynh
  [show abstract] [hide abstract]
  ABSTRACT: The relative ligand donor strengths of 10 pyrazole-derived ligands has been determined with great accuracy, making use of the interdependence between the donor strength of the co-ligand and the (13)C NMR chemical shift of the (i)Pr(2)-bimy carbene signal in trans-[PdBr(2)((i)Pr(2)-bimy)L] complexes ((i)Pr(2)-bimy = 1,3-diisopropylbenzimidazolin-2-ylidene; L = pyrazole-derived ligand). Even subtle variations in the substitution pattern of the pyrazole backbone up to three bonds away from the coordinating nitrogen could be detected reliably using this methodology. Alkylation experiments conducted on the pyrazoles using electrophiles of varied reactivity (ethyl bromide, ethyl iodide, and trimethyloxonium tetrafluoroborate) served as a benchmark to rank the pyrazoles in three groups of gradually increasing nucleophilicity, which correlated well with their determined donor strength.
  Dalton Transactions 05/2012; 41(28):8600-8. · 3.84 Impact Factor
• Source

  Available from: Han Vinh Huynh

  Article: Sulfur-functionalized N-heterocyclic carbene complexes of Pd(II): syntheses, structures and catalytic activities.

  Dan Yuan, Han Vinh Huynh
  [show abstract] [hide abstract]
  ABSTRACT: N-heterocyclic carbenes (NHCs) can be easily modified by introducing functional groups at the nitrogen atoms, which leads to versatile coordination chemistry as well as diverse catalytic applications of the resulting complexes. This article summarizes our contributions to the field of NHCs bearing different types of sulfur functions, i.e., thioether, sulfoxide, thiophene, and thiolato. The experimental evidence for the truly hemilabile coordination behavior of a Pd(II) thioether-NHC complex has been reported as well. In addition, complexes bearing rigid CSC-pincer ligands have been synthesized and the reasons for pincer versus pseudo-pincer formation investigated. Incorporation of the electron-rich thiolato function resulted in the isolation of structurally diverse complexes. The catalytic activities of selected complexes have been tested in Suzuki-Miyaura, Mizoroki-Heck and hydroamination reactions.
  Molecules 01/2012; 17(3):2491-517. · 2.39 Impact Factor