Structural and theoretical studies of mono and di-insertion of symmetric alkynes into the Pd–C σ bond of cyclopalladated secondary (tert-butyl and ethyl) benzylamines

The reactivity of the dinuclear cyclopalladated complexes derived from secondary benzylamines, [Pd2{(C,N)eC6H4CH2NH(R)}2(m-X)2] [X ¼ Br, R ¼ t-Bu (1a); X ¼ Cl, R ¼ t-Bu (1b); X ¼ Cl, R ¼ Et (1c)] is reported. 1a reacted with dimethyl acetylenedicarboxylate (DMAD) to yield the mono-inserted complex [Pd2{(C,N)eC(CO2Me)]C(CO2Me)C6H4CH2NH(t-Bu)}2(m-Br)2] (2a). 1a, 1b and 1c reacted with (R0) C^C(R0) (R0¼ CO2Me, Ph) to give [Pd{(C,N) C(R0)]C(R0)C(R0)]C(R0)C6H4CH2NH(R)}X] [X ¼ Br, R ¼ t-Bu, R0¼ CO2Me (3a); X ¼ Cl, R ¼ t-Bu, R0¼ Ph (2b); X ¼ Cl, R ¼ Et, R0¼ Ph (2c)] through a double insertion of the alkyne into the PdeC s bond. 2c also reacts with Ag(CF3SO3) and pyridine to give mononuclear cationic complex [Pd{(C,N)eC(Ph)]C(Ph)C(Ph)]C(Ph)}C6H4CH2NH(Et)(py)]CF3SO3 (3c). The crystal structures of di-inserted complexes 2b, 2c and 3c have been determined by X-ray diffraction studies. Their molecular structures showed that the conformation of the C]C double bonds within the buta- dienyl group attached to the aromatic ring was transecis. Density functional theory (DFT) calculations also indicated that this arrangement is more stable than other possible conformations

A novel Pd(II) CNO pincer complex of MR (methyl red): Synthesis, crystal structure, interaction with human serum albumin (HSA): In vitro and molecular docking

The C-H activation of methyl red (MR) (MR = 2-[4-(dimethylamino)phenyl]diazenylbenzoic acid) was achieved by reaction with Pd(OAc)2 under mild conditions. Metalation occurred at the ortho-position of the (dimethylamino)phenyl group in methyl red and the cyclometalated CNO pincer complex was obtained in good yield. The molecular structure shows that MR forms 6,5-fused chelate rings at the Pd(ii) center. Interaction of the pincer complex with human serum albumin (HSA) has been studied by fluorescence spectroscopy and circular dichroism. Fluorescence quenching at different temperatures was analyzed using the classical Stern-Volmer equation, and a dynamic quenching mechanism was proposed. Energy resonance transfer between HSA and 1aⲠwas examined according to Förster's non-radiative energy transfer theory. A distance of about 5.06 à between the complex and Trp214 (HSA) was obtained. Docking studies showed that the binding pocket of subdomain IIA of HSA is the preferable pincer complex binding site

NC Palladacycles and C,C-chelating phosphorus ylide complexes: synthesis, X-ray characterization, and comparison of the catalytic activity in the Suzuki-Miyaura reaction

<p>Six secondary amine palladacycles bearing monodentate ligands (<b>1a</b>, <b>2a</b>), 1,2-bis(diphenylphosphino)ethane (dppe) and 1,3-bis(diphenylphosphino)propane (dppp) containing bridging and bidentate ligands (<b>1b</b>, <b>2b</b>–<b>d</b>), and four <i>C</i>,<i>C</i>-type phosphorus ylide complexes containing thiourea (tu) (<b>3a</b>), phenyl isothiocyanate (<b>4a</b>), and bridging and terminal azide groups (<b>5</b> and <b>5a</b>) have been synthesized. Resulting complexes have been characterized by elemental analyses, IR, ¹H-, ¹³C{¹H}-, and ³¹P{¹H}-NMR spectroscopy with single crystal X-ray structure determination of <b>1a</b> and <b>2a</b>. The Pd in <b>1a</b> and <b>2a</b> occupies the center of a slightly distorted square planar environment formed by <i>C</i>_aryl, <i>N</i>_amine, <i>N</i>_pyridine, and Cl. The catalytic efficiency of complexes showed that in most cases, amine palladacycles display better catalytic activities than the phosphorus ylide Pd(II) complexes. Comparison between bidentate and bridging dppe complexes showed that dppe-bridged dimer <b>2d</b> has higher catalytic activity than dppe bidentate complex.</p