F. H. Allen

Crystal and molecular structure of thalidomide, N-(α-glutarimido)-phthalimide

Crystals of the N-(α-glutarimido)-derivative of phthalimide (Thalidomide), C13H10N2O4, are monoclinic, space group P21/n, with a= 8·233 (1), b= 10·070(2), c= 14·865(2)A, β= 102·53(2)°, and Z= 4. The structure has been determined by direct methods using diffractometer data; full-matrix least-squares refinement has reduced R to 0·053 for 1855 observed reflections, which were corrected for absorption. The phthalimide residue is significantly non-planar, while the glutarimido-moiety approximates a half-chair conformation; the central N–C bond is equatorial. The angle between the mean phthalimide and glutarimido-planes is 81°. Pairs of centrosymmetrically related molecules form hydrogen-bonded dimers through N–H ⋯ O contacts of 2·928 A between glutarimido-residues.

Crystal and molecular structure of thalidomide

Crystal structure analysis of Thalidomide has established the molecular conformation and dimensions; the glutarimido-residue is twisted 81·3° relative to the phthalimide moiety.

Crystal and molecular structure of anti-3′,4′-difluoro-2-hydroxyiminopropiophenone

The two isomers of 3′,4′-difluoro-2-hydroxyiminopropiophenone show different biological activities. Crystals of the more active form are monoclinic, space-group Cc, with a= 3·848, b= 20·695, c= 11·585 A, β= 103·83°, and Z= 4. The structure was determined from visually estimated Weissenberg data by a direct phase-determining method, and refined to R 0·075 for 748 reflexions. The analysis shows this isomer to be the anti-form and confirms the trans-oid arrangement of the carbonyl and hydroxyimino-groups. The molecule may be described by the three planes defined by the difluorophenyl, carbonyl, and hydroxyimino-groups, which are twisted with respect to each other. The structure contains intermolecular O–H⋯O bonds of 2·70 A.

Crystal and molecular structure of a bis-p-bromobenzoate derivative of cyclograndisolide [3α-methoxy-9,19-cyclo-9β-lanost-24-en-27,23(R)-olide]

Crystals of a bis-p-bromobenzoate derivative of cyclograndisolide, C45H60Br2O5, are orthorhombic, a= 6·635(1), b= 20·919(3), c= 30·530(5)A, Z= 4, space group P212121. The structure was determined with Cu-Kα diffractometer data by Patterson, electron-density, and least-squares methods, the final R being 0·096 for 1518 observed reflexions. The absolute configuration was determined by the anomalous dispersion method. The presence of a 9,19-cyclopropane system is confirmed, and the chemically assigned stereochemistry is upheld. The A ring of the triterpene nucleus is in the chair form, but the presence of the cyclopropane, and of a trans-fused five-membered ring D produces large distortions in rings B and C. There is a short intermolecular Br … Br distance of 3·57 A.

Crystal and molecular structure of the bromoindole derivative of 3β-methoxy-21-keto-Δ13-serratene

Crystals of the bromoindole derivative of 3β-methoxy-21-keto-Δ13-serratene, C37H52NOBr,C2H5OH, are orthorhombic, a= 10·203 ± 4, b= 11·124 ± 2, c= 31·230 ± 12 A, Z= 4, space group P212121. The structure was determined with Cu-Kα diffractometer data by Patterson, electron-density, and block-diagonal least-squares methods, the final R being 0·086 for 1459 observed reflexions. The absolute configuration was determined by the anomalous dispersion method.The seven-membered ring adopts the chair conformation, but there is some out-of-plane distortion at the Δ13-double bond. The plane through the steroid nucleus is slightly bowed to minimize trans-annular methyl–methyl interactions.

Crystal structure of dimethyltin bisfluorosulphate

Crystals of dimethyltin bisfluorosulphate, Me2Sn(SO3F)2, are monoclinic, a= 7·813(2), b= 8·399(2), c= 8·143(2)A, β= 117·13(2)°, Z= 2, space group P21/c. The structure was determined with Mo-Kα diffractometer data by Patterson and full-matrix least-squares methods, the final R being 0·036 for 643 observed reflexions. The structure consists of polymeric sheets parallel to (100), with the fluorosulphate groups acting as bridging ligands between linear dimethyltin units. The tin atom is octahedrally co-ordinated to two methyl groups, Sn–C 2·08(1)A, and four oxygen atoms, Sn–O 2·24(1)A. The SO3 F group does not deviate significantly from C3v symmetry, and has the mean dimensions, S–O 1·47(1), S–F 1·56(1)A, O–S–O 112, and F–S–O 107°.

Crystal structure of cis-benzocyclobutene-1,2-diol dinitrate

Crystals of cis-benzocyclobutene-1,2-diol dinitrate, C8H6N2O6, are monoclinic, space group P21/n, a= 7·438(1)b= 15·733(2), c= 8·136(2)A, β= 98·01(2)°, Z= 4. The structure was determined by direct methods, with Cu-Kα diffractometer data. Full-matrix least-squares refinement reduced R to 0·048 for 1110 observed data. The mean planes through the two rings make an angle of 4·3° and the four-membered ring is slightly puckered, the mean dihedral fold angle being 3·0°. Both nitrate groups are planar and make an angle of 78·6° with each other. There are differences in the valence angles at C(1) and C(2), which minimize intramolecular non-bonded repulsions.

Crystal structure of benzocyclobutene-1,2-dione

Crystals of benzocyclobutene-1,2-dione (C8H4O2) are orthorhombic, a= 7·938, b= 10·741, c= 7·135 A, Z= 4, space group Pbc21. The structure was determined, with visually estimated Weissenberg data (Cu-Kα radiation), from a three-dimensional sharpened Patterson function, and full-matrix least-squares refinement reduced R to 0·080 for 432 observed reflexions. A concurrent application of direct methods to the centrosymmetric [001] projection yielded an identical solution. The two rings are planar, but the molecule as a whole is very slightly bowed. There are significant angular distortions in the benzene ring owing to the strain introduced by fusion to a four-membered ring. The packing arrangement is totally determined by van der Waals interactions.

Crystal structure of 4-biphenylylferrocene

Crystals of 4-biphenylylferrocene are monoclinic, a= 19·18, b= 7·79, c= 10·85 (all σ ca. 0·01)A, β= 91·8 (1)°, Z= 4, space group P21; there are two molecules of C22H18Fe per asymmetric unit. The structure was determined with Fe-Kα scintillation counter data (corrected for absorption) by Patterson and Fourier methods and was refined by least-squares calculations, the final R being 0·115 for 1579 observed reflexions. The mean bond distances are Fe–C = 2·02, C–C (five-membered rings)= 1·42, C–C (six-membered rings)= 1·40, C–C (between rings)= 1·50 A. The two independent molecules have slightly different conformations. In one the cyclopentadienyl rings are oriented about midway between the eclipsed and staggered conformations, and the first six-membered ring is rotated 10° out of the plane of the cyclopentadienyl ring to which it is bonded, with the second six-membered ring rotated a further 7°. In the second molecule the cyclopentadienyl rings are only ca. 5° from the fully eclipsed position, and the six-membered ring rotations are 2 and 12°. The intermolecular separations correspond to van der Waals interactions.