Synthesis of cis-p-dioxano-12-crown-4 and X-ray crystallography of the (1:1) complex with lithium thiocyanate

The synthesis of a novel 12-crown-4 analogue (cis-p-dioxano-12-crown-4 or cis-3,6,9,13,15-pentaoxabicyclo[9.3.1]pentadecane) is described. The (1:1) LiNCS complex crystallizes in the monoclinic Cc space group; a = 8.4973(2) Å, b = 18.0659(4) Å, c = 8.9168(1) Å, and β = 90.713(1)° with Z = 4. The crown adopts C1 symmetry to which the Li+ is coordinated in a rectangular pyramid with an apical NCS

(Terpyridine)palladium(II) complexes of phenylcyanamide ligands

(Terpyridine)palladium(II) complexes of phenylcyanamide anion ligands have been prepared and characterized by UV-vis, IR, and 1H-NMR spectroscopies. A crystal structure determination of the complex [Pd(terpy)(2,6-Cl2-pcyd)] [PF6] has been performed. The overall geometry of the complex is approximately planar with a dihedral angle of 2.16(16)∘ between the best plane fit of the palladium coordination sphere and that for the phenyl ring of the phenylcyanamide ligand. Crystal structure data for the complex: C22H14N5Cl2PF6Pd, monoclinic crystal system and space group P21/n, with a = 8.185(5) Å, b = 13.606(7) Å, c = 21.163(5) Å,β = 90.50(3)∘, V= 2356.8(20) Å−3, and Z = 4. The structure was refined by using 3233 Mo Kα reflections with I > 2.5σ(I) to an R factor of 0.034. The UV-vis spectra of the complexes showed a broad band centered at approximately 400 nm which has been assigned to a πnb → σ* LMCT transition of the Pd(II)-NCN chromophore

(1,3-Bis(2′-pyridylimino)isoindolinato)nickel(II) complexes of phenylcyanamido ligands: crystal structure, electronic absorption spectroscopy and solvent adduct studies

Complexes of the formula Ni(L)X, where L=1,3-bis(2′-pyridylimino)isoindolinato and X=Cl, Br, N3, NCS, 2-Clpcyd, 4-Clpcyd, 2,3-Cl2pcyd,2,6-Cl2pcyd, 2,4,5-Cl3pcyd and 2,3,5,6-Cl4pcyd, have been synthesized and characterized by elemental analysis, and IR, 1H NMR and UVVis spectroscopies. A crystal structure determination of Ni(L)(2-Clpcyd) showed nickel in a distorted square planar coordination sphere of nitrogen donor atoms in which the phenylcyanamido ligand is coordinated to Ni(II) via the terminal nitrogen. The solvent coordination equilibria of Ni(L)(pcyd) complexes was also investigated and the results suggest that both electronic and steric factors play important roles in determining the stability of the solvated complex

1H dynamic NMR and x-ray crystal structure studies of conformational preferences in dibenzo [c,h] [1,6] diazecines

The conformational equilibria and preferences in dibenzo[c,h] [1,6]diazecines have been investigated by 1H DNMR measurements and X-ray crystallography. It has been found that restricted rotation about the exocyclic N-S bond in 6,13-ditosyl-6,7,13,14-tetrahydro-5H,12H-dibenzo[c,h][1,6] diazecine 2 becomes slow on the NMR timescale in the temperature range 200-300 K. The free energy of activation was determined to be 43.5 ± 0.5 kJ mol-1 for this dynamic process. Steric hindrance at the transition state is deemed to be the most important contribution to the N,S barrier. From X-ray crystal structure analyses, it appears that the influence of the N-inversion on this barrier is negligible. The conformation in the solid state is also the preferred one in solution. The X-ray structure illustrates the spatial vicinity of the tosyl groups relative to the annelated benzene moieties of the 10-membered ring. Consistent with these results are high field shifts and corresponding splittings in the aromatic part of the 1H NMR spectrum of compound 2