The crystal structure of strychnine hydrogen bromide

Abstract

The structure of strychnine hydrobromide, CalHzaNaO,.HBr.2H,O, has been fully determined. The crystals are orthorhombic with space group P212121, and cell dimensions a=7.64, b=7.70, c = 33.20 A. The positions of the bromine atoms were found from Patterson projections. The general intensities were determined and a three-dimensional Fourier synthesis was calculated in which the F values were given the phases of the bromine atoms alone. Also the vector convergence diagram, lining the bromine positions, was obtained from the three-dimensional Patterson summation, and this was also employed to deduce the parameters of the complete structure. The structure possesses sheets of bromine atoms approximately at levels z = [ and ~ which axe linl~ed together by water molecules. Each bromine atom is bonded to a strychnine molecule through the basic nitrogen atom of each molecule. The strychnine molecule found has a configuration identical with that found by Bokhoven, Schoone & Bijvoet, and has the same structure as that now favoured by the organic chemists.

The crystal and molecular structure of dl-betaprodine hydrobromide

“…Because of the close proximity of the heavy Br, however, the hydrogen atom that would be involved in such bonding was the only one in the structure which was not located with any certainty, so that the bond shortening may be due, in part, to dipole-dipole interactions. Comparable Br to N distances (3.17 to 3.38 /~), indicative of hydrogen bonding, have been reported in certain other organic hydrobromides (Robertson & Beevers, 1951;Trommel & Bijvoet, 1954;Sire, 1955;Hanson & Ahmed, 1958). The three Br-N-C angles STRUCTURE OF dl-BETAPRODINE HYDROBROMIDE (Br-:N( 1 )-C(6) = 98 °, Br-N( 1 )-CH~ = 98 °, Br-N( 1 )-C(2) =126 ° ) in the present structure differ more widely from the tetrahedral value than do the corresponding C1-N-C angles (106.6 to 110.0 °) in the crystal structure of alphaprodine hydrochloride (Kartha, Ahmed & Barnes, 1961) but are similar to those in the crystal structure of the monoclinic form of d-methadone hydrobromide (Br-N-Cs = 96 °, Br-N-C9 = 97 °, Br-N-C6 = 120 °, calculated from data of Hanson & Ahmed, 1958, where Cs and C9 both represent methyl groups).…”

Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.

“…The optical rotation of this compound (aTO) was originally reported to be zero in acetone solvent but was subsequently determined to be (+) in hexane with a plane-positive optical rotatory dispersion curve (see footnote 35 and figure 1 Previous structure determinations on the absolute configuration of (-)-strychnine had produced conflicting results. The x-ray structure analysis was originally performed by Bokhoven et al (24) and by Robertson and Beevers (25,26). The former group (24) used the isomorphous replacement method with strychninium sulfate and strychninium selenate, whereas the latter group used strychnine hydrobromide dihydrate.…”

The crystal structure of spermine phosphate hexahydrate

“…The approximate coordinates of the phosphorus atom were determined by inspection of rather high peaks originating from the symmetry-equivalent phosphorus atoms. The vector convergence method (Robertson & Beevers, 1951) was then applied and the approximate coordinates of six oxygen a~oms were de~ermined was presen~ A subsequen~ s~ruo~ure factor ea]eula~ion A subsequent structure faotor calculation gave *he wi~h coordinates derived from ~his syn*hesis gave an B index 059, bu~ ~here appeared to be no serious R index of 038 diserepanoy between the observed and ealeula*ed Two cycles of refinemen~ by ~he ~hree dimensiona] s~rueture factors The signs of abou~ 967 reflections Fo synthesis followed by a *hree dimensional dif were adequately de~ermined and a ~hree dimensional ferenee synthesis reduced R t;o 016 ~Tex~, ~he strue l~ourier synthesis was computed In the Fourier map, ~ure was refined by the *hree dimensional least electron-density peaks corresponding t~o all seven squares me~hod. Throughout *he calculation, 4:16 a~oms of ~he spermine molecule clearly showed ~p reflections which are ~oo weak ~o be observed were %oget~her with the at~oms of ~he phosphate group and omitted.…”