Calculations on members of the oligo(cyclohexylidene) series [(n), n = 1-5)] and related tetrahydro-4H-thiopyran end-capped analogues [(n), n = 1-4)] show a strong through-bond coupling between their pi bonds and sulfur lone pairs (Lp(pi)S). This coupling is mediated by an interaction between the H(ax)-C-C-H(ax) structural sub-units and the pi bonds connecting the cyclohexyl moieties. A compari...

the catalytic acvtivity of dimeric and monomeric ortho-palladated complexes [pd{c6h2(ch2nh2-(ome)2,3,4}(µ-cl)]2)2) and [pd{c6h2(ch2nh2-(ome)2,3,4}cl(pph3)](3), was investigated in heck cross-coupling reaction. these complexes are more active and efficient catalysts for heck cross-coupling reaction. the palladium complexes 2 and 3 is employed in the heck cross-coupling reaction between styrene a...

Copper-catalyzed (or -mediated) asymmetric coupling reactions have received significant attention over the past few years. Especially the coupling reactions of aryl or alkyl halides with nucleophiles became a very powerful tool for the formation of C-C, C-N, C-O and other carbon-heteroatom bonds as well as for the construction of heteroatom-containing ring systems. This review summarizes the re...

Electrostatic (through-space) and covalent (through-bond) contributions to couplings involving the C[double bond]O and C[bond]N vibrational stretching modes of the amide group in the alpha-helix and the parallel and antiparallel beta-sheet structures of alanine polypeptides are analyzed. Coupling constants computed at the density functional theory level are compared with the transition dipole c...

A 13C, 15N-labeled DNA hairpin molecule of the sequence d(GCGAAGC) ) d(G1C2G3A4A5G6C7) was investigated by NMR spectroscopy to determine one-bond and two-bond NMR spin-spin coupling constants 1J(X, H) (X ) C, N), 1J(C, X) (X ) C, N), and 2J(X,H) (X ) C,N). Measured J values for the WatsonCrick (WC) base-pairs G1C7, G6C2, the mismatched base-pair G3A5 and the unpaired base A4 were compared with ...