Donald Rogers

Crystal structure of the red form of 2,2′-bipyridyldichloroplatinum(II)

The crystal structure of the red form of [(2,2′-bipyridyl)PtCl2] has been determined from X-ray diffractometer data. Crystals are orthorhombic, space group Cmcm, with a= 17·666(2), b= 9·086(1), c= 6·803(1)A, Z= 4. The structure was derived from 554 intensities, by Patterson and Fourier methods, and refined by least squares to R 0·024. The structure comprises layers of monomeric molecules lying parallel to (001) and separated by 3·40 A. The platinum atoms are nearly superimposed and are separated by 3·45 A. There is marked pleochroism, the maximum absorption of the broad line at 520 nm occurring when the electric vector is parallel to the strings of platinum atoms.Unit-cell parameters for the yellow form are a= 15·93, b= 7·22, c= 18·38 A; space group Pbca, Z= 8.

The crystal structure of 3-epicaryoptin and the reversal of the currently accepted absolute configuration of clerodin

Evidence, based on an X-ray assignmet of the chirality of 3-epicaryopti and a fresh X-ray study of clerodin bromolactone, is presented for the reversal of the long-held absolute configuration of clerodin, and new terminology is suggested to avoid confusion in future.

The crystal structure of (±)-dehydroaltenusin

The crystal structure of (±)-dehydroaltenusin, C15H12O6, has been determined by direct X-ray crystallographic analysis.

Isolation, Characterisation and Oxidation of Isomeric Ferrelactone Complexes.

Abstract Irradiation of 1,2-epoxy-l-vinylcyclopentane (1) in the presence of Fe(CO)5 leads to the formation of isomeric syn -and anti - ferrelactones (2) and (3). The structures of these complexes were determined by X-ray crystallographic methods and on oxidation gave different ratios of β- and δ-lactones.

The crystal and molecular structure of streptomycin oxime selenate tetrahydrate

The crystal and molecular structure and absolute configuration of the antibiotic streptomycin have been determined by an X-ray study of the hydrated oxime selenate. The compound (C21H40N8O12. 1 1/2 H2SeO4.4H2O) crystallizes in the monoclinic space group C2, with cell dimensions a = 17.10(1), b = 14.36(1), c = 16.13(1)Å∥, β = 108.0(2)°; Z = 4 The structure was solved by the heavy-atom method, by using 3236 visually-estimated intensities, and refined to a conventional R of 0.086. The analysis has confirmed that streptomycin consists of three fragments, an N -methyl- α-L-glucosamine ring, an α-L-streptose and a streptidine ring, linked together by two glycosidic bonds. The crystal structure contains an elaborate network of hydrogen bonds linking selenate and streptomycin oxime ions and water molecules, analysis of which, though somewhat hampered by inability to observe the hydrogen atoms experimentally, reveals a disordered hydrogen bond occurring between two diad-related water molecules.

Steric factors in nitrite co-ordination. Part 1. Crystal structure of bis(NN′-diethylethylenediamine)(nitrito-OO′)nickel(II) tetrafluoroborate

The preparations and electronic and i.r. spectra are reported for the complexes [NiL2(NO2)]X (X = BF4 or ClO4; L = RHNCH2CH2NHR or R2NCH2CH2NH2, R = Me or Et). The structure of the title complex has been determined from three-dimensional X-ray diffractometer data. The crystals are monoclinic, with unit-cell dimensions a= 11.338(1), b= 16.291(2), c= 11.934(1)A, and β= 112.015(8)°, space group P21/c, and Z= 4. The structure has been refined by least squares to R 0.053 for 2 522 independent reflections. The complex is monomeric with a chelating nitrite group forming part of a distorted-octahedral environment about nickel. The diethylethylenediamine ligands are arranged in cis positions and there is an approximation to a diad in the cation. The steric factors leading to this geometry, as distinct from M–ONO–M bridging, are discussed.

Structure of a new triterpene ether from salacia prinoides dc: x-ray investigation of the dibromo derivative

An X-ray diffraction study has established the structure of the dibromo derivative of a new triterpene ether isolated from Salacia prinoides DC. as (IIb), a derivative of friedelane.

X-ray comparison of the molecular structures of 4a-methyl-1,3,9-triphenyl-4a-H-fluorene and its Fe(CO)3 complex

Abstract 4 a -Methyl-1,3,9-triphenyl-4 a-H -fluorene, which is a tetrameric product formed on vigorous dehydration of acetophenone, has structure 1 , in which rings A and B form an indene fragment, the diene ring C approximates to half-chair configuration, and the three phenyl rings, D, E, and F, are considerably rotated relative to rings B,C about their connecting bonds. In the Fe(CO) 3 complex, 3 , a marked change has occurred in the conformation of ring C to allow Fe coordination on the side opposite to the methyl group. The complexed FeC distances are 2.117, 2.049, 2.067, 2.220 A, and there are marked changes in the bond lengths in the complexed diene, but all other bond lengths correspond closely in the two molecules. 1 (C 32 H 24 ) is triclinic, a 12.506, b 10.237, c 10.121 A, α 108.53, β 84.93, γ 112.32°; space group P 1 , Z = 2. The complex, C 32 H 24 Fe(CO) 3 , is monoclinic, a 30.283, b 12.709, c 14.514 A, β 92.73°; space group B 2 1 / c , Z = 8.

A novel rearrangement of 2-methoxy-1, 4-naphthoquinone to 3-nitromethylene phthalide

Abstract 2-Methoxynaphthoquinone under nitrating conditions afforded 3-nitromethylene phthalide, the structure of which was solved by an X-ray crystallographic analysis.

Revised structures of the triterpenes Q, T, and U from Salacia prinoides DC; X-ray crystal structure of triterpene T

An X-ray study of triterpene T(C30H48O3) has shown that the related compounds Q, T, and U which are derivatives of 1,3-diketofriedelane have their third oxygen function at C(26) intead of C(24) as previously proposed; rings D and E occur in a cis-fused boat–boat (‘trimaran’) conformation.