J. W. Buchler, A. Cian, J. Fischer
Jun 1, 1986
Citations
0
Influential Citations
138
Citations
Quality indicators
Journal
Journal of the American Chemical Society
Abstract
The synthesis, spectral characterization, and crystal structure determination of novel lanthanoid porphyrins, i.e., cerium(IV) bis(octaethylporphyrinate) (Ce(OEP)/sub 2/) and dicerium(III) tris(octaethylporphyrinate)(Ce/sub 2/(OEP)/sub 3/), are described. Synthesis is achieved by prolonged boiling of cerium(III) acetylacetonate (Ce(acac)/sub 3/) and octaethylporphyrin (H/sub 2/(OEP)) in 1,2,4-trichlorobenzene, C/sub 6/H/sub 3/Cl/sub 3/, followed by chromatography on basic alumina. Solutions of reddish-brown, diamagnetic Ce(OEP)/sub 2/ slowly decompose, depositing scarcely soluble, brown paramagnetic Ce/sub 2/(OEP)/sub 3/. The solution structures are deduced from /sup 1/H resonance spectra, and the solid-state structures are proved by X-ray crystallography of monoclinic Ce(OEP)/sub 2/ (P2/sup 1//n) and monoclinic (P2/sub 1//c) or tetragonal (I 4) modifications of bis(trichlorobenzene) or tetrakis(benzene) solvates of Ce/sub 2/(OEP)/sub 3/. The bisporphyrinate is a double-decker while the trisporphyrinates are triple-decker molecules. The cerium ions appear in an approximate square-antiprismatic geometry with Ce-N distances of 2.48 A for the Ce/sup IV/ and of about 2.50 A (external porphyrinate) and 2.75 A (internal porphyrinate) for the Ce/sup III/ sandwich systems. The external porphyrinates are bent away from the cerium ions in a saucer-like shape, whereas the internal porphyrinate is planar. The two mean planes of the 24 core atoms of the individual porphyrin rings lie 3.40 or 3.54 A away from eachmore » other in the double-decker or triple-decker, respectively.« less