Showing papers by "Thomas F. Koetzle published in 1985"
43 citations
TL;DR: The structure of lithium hydrogen phthalate monohydrate has been refined based upon neutron diffraction data obtained at three temperatures: 15, 100, and 298 K as discussed by the authors, and all bond distances have been determined with precision better than 0.002 A.
Abstract: The structure of lithium hydrogen phthalate monohydrate has been refined based upon neutron diffraction data obtained at three temperatures: 15, 100, and 298 K. All bond distances have been determined with precision better than 0.002 A. The two crystallographically independent hydrogen phthalate anions in the unit cell both possess very short intramolecular O⋅⋅⋅H⋅⋅⋅O hydrogen bonds with O⋅⋅⋅O≊2.4 A and ∠O⋅⋅⋅H⋅⋅⋅O≊170°. One of these linkages is very decidedly asymmetric, with O⋅⋅⋅H=1.122(1) A and H⋅⋅⋅O=1.294(1) A at 15 K, reflecting the fact that the two O atoms have quite different environments in the crystal. The second O⋅⋅⋅H⋅⋅⋅O bond is more nearly symmetric, with O⋅⋅⋅H=1.195(1) A and H⋅⋅⋅O=1.205(1) A at 15 K, but the difference between the two distances is still significant. The asymmetry of the short hydrogen bonds appears somewhat more pronounced at 298 K than at the lower temperatures. A corresponding shift with temperature of the H atom in the short intramolecular hydrogen bond was found previously in 2,3‐pyridinedicarboxylic acid, which has a molecular geometry similar to that found here.
42 citations
18 citations
TL;DR: In this paper, photolysis of pentacarbonyl iron in the presence of diphenylketene yields a novel eta/sup 1/eta/sup 3/ diphenyketene complex which exhibits the heterocumulene precursor in a σ-allyl/sigma-acyl coordination with one phenyl ring engaged in bonding of this ligand to the transition-metal center.
Abstract: Photolysis of pentacarbonyl iron in the presence of diphenylketene yields a novel eta/sup 1/.eta/sup 3/ diphenylketene complex. This compound according to a single-crystal neutron diffraction study, exhibits the heterocumulene precursor in a ..pi..-allyl/sigma-acyl coordination with one phenyl ring engaged in ..pi.. bonding of this ligand to the transition-metal center. Upon treatment of the diphenylketene with excess enneacarbonyldiiron, a dinuclear iron complex is formed in a 77% yield. This molecule was shown by neutron diffraction techniques to contain a bridging hydrocarbon ligand related to the original ketene ligand in the original iron complex by decarbonylation and 1,3-hydrogen shift. Crystallographic data are presented for both the complexes.
17 citations
TL;DR: In this paper, the crystal and molecular structure of the pentahydrido complex ReH/sub 5/(PMePh/sub 2/)/sub 3/, has been determined by x-ray diffraction techniques at room temperature and refined against neutron diffraction data obtained at 20 K to yield precise locations for all atoms.
Abstract: The crystal and molecular structure of the pentahydrido complex ReH/sub 5/(PMePh/sub 2/)/sub 3/, has been determined by x-ray diffraction techniques at room temperature and refined against neutron diffraction data obtained at 20 K to yield precise locations for all atoms. The two independent molecules in the unit cell possess essentially identical dodecahedral cores, with the three phosphines and one hydride in B (5-neighbor) positions and the remaining four hydrides in A (4-neighbor) sites. The mean Re-H bond distance is 1.688 (5)A, which is in agreement with that found in K/sub 2/ReH/sub 9/(1.68(1)A). At convergence with anisotropic thermal parameters refined for all 174 atoms (1568 variables), agreement factors are presented for 11,374 independent neutron observations. Crystal data at 20.0(5)K are presented for the complex. In solution, /sup 1/H and /sup 31/P (/sup 1/H) NMR meausrements indicated that the compounds are fluxional molecules, with magnetically equivalent hydrides and phosphides at 25/sup 0/C.