Trevor J. King

Crystal and molecular structure of compactin, a new antifungal metabolite from Penicillium brevicompactum

The structure of compactin (I){7-[1,2,6,7,8,8a-hexahydro-2-methyl-8-(2-methylbutyryloxy)naphthyl]-3-hydroxyheptan-5-olide}, a metabolite isolated from cultures of Penicillium brevicompactum, has been determined by a combination of spectroscopic, chemical, and X-ray crystallographic methods.

Clavulanic acid, a novel β-lactam isolated from Streptomyces clavuligerus; X-ray crystal structure analysis

The structure of clavulanic acid, a β-lactamase inhibitor isolated from Streptomyces clavuligerus, has been shown by spectroscopic methods and X-ray analysis to be a novel fused β-lactam.

Structural studies in main group chemistry : XXIII. Estertin derivatives, structural and spectroscopic studies

Abstract The crystal and molecular structures of three ‘estertin’ derivatives, Cl3SnCH2CH2CO2Me, Cl2Sn[CH2CH2CO2Me]2 and Cl2Sn[CH2CH2CONH2]2, are reported. Cystals of Cl3SnCH2CH2CO2Me are orthorhombic, space group P212121, with a 9.2981, b 10.5389, and c 10.0885 A; those of Cl2Sn[CH2CH2CO2Me]2 are monoclinic, space group P21/c, with a 8.0107, b 15.9104, c 13.4109 A, and β 131.0044°; and those of Cl2Sn[CH2CH2CONH2]2 are also monoclinic, space group Cc, with a 9.1314, b 12.8672, c 13.0317 A, and β 126.6032°. Crystals of Cl3Sn(CH2CH2CO2Me) and Cl2Sn[CH2CH2CO2Me]2 both consist of discrete molecules, but extensive intermolecular hydrogen-bonding occurs in crystals of Cl2Sn[CH2CH2CONH2]2. Intramolecular carbonyl oxygen-to-tin coordination occurs in all three compounds. Vibrational and mass spectra are also reported, and are assigned in accordance with the determined structures. Tin-119 Mossbauer studies demonstrate that it is possible to investigate the nature of organotin additives to PVC by this method. Preliminary investigations show that Bu2Sn(IOTG)2 added to PVC undergoes only partial IOTG for chlorine exchange at the milling stage, but is completely converted to Bu2SnCl2 after thermal degradation. Both BuAcSn(IOTG)3 and BuAcSn(βMeOct)3 undergo complete sulphur ligand for Cl exchange during the milling process giving BuAcSnCl3 as the species detected. Degradation to some unidentified organotin species occurs on heating.

Laurenyne, a new acetylene from Laurencia obtusa: crystal structure and absolute configuration

Abstract Laurenyne, a new chloroacetylene from the red form of the alga Laurencia obtusa has been identified and its crystal structure determined.

The cymopols, a group of prenylated bromohydroquinones from the green calcareous alga Cympolia barbata

Seven new hydroquinones have been isolated from the green alga Cymopolia barbata. These are cymopol [2-bromo-5-(3,7-dimethylocta-2,6-dienyl)hydroquinone] and its monomethyl ether, cyclocymopol [1-bromo-3-(4-bromo-2,5-dihydroxybenzyl)-2,2-dimethyl-4-methylenecyclohexane] and its monomethyl ether, cymopolone [(4-bromo-2,5-dihydroxyphenyl)trans-(2,6-dimethylhepta-1,5-dienyl) ketone], and its cis-isomer, and cymopochromenol [7-bromo-6-hydroxy-2-methyl-2-(4-methylpent-3-enyl)-2H-1-benzopyran]. The structure and absolute stereochemistry of cyclocymopol monomethyl ether acetate were established by X-ray crystallography.

The relative and absolute configuration of clerocidin and its cometabolites

Abstract The structures of clerocidin and five cometabolites have been established by chemical interconversion, spectral, and X-ray crystallographic methods.

The Mössbauer recoil-free fraction and structure. Part 3. Triorganotin arylazobenzoates

The structures of five triorganotin arylazobenzoates, SnR3[O2CC6H4(N2R′)-o], have been investigated by tin-119 Mossbauer spectroscopy, and in one case by X-ray crystallography. Crystals of the compound, (4), with R = Ph and R′= 2-hydroxy-5-methylphenyl are monoclinic, space group C2/c, with a= 32.525(6), b= 9.475(5), c= 19.957(5)A, β= 103.034(5)°, and Z= 8. The structure was solved by Patterson and Fourier methods using the intensities of 4 192 independent, non-zero reflections to a final R value of 0.0524, and comprises independent, non-interacting molecules. The carboxylato-group chelates the tin atom [Sn–O 2.070(5) and 2.463(7)A] resulting in a distorted cis-SnC3O2 five co-ordinated geometry at tin. Tin-119 Mossbauer spectral data indicate that two derivatives (R = Ph, R′= 4-dimethylaminophenyl and 2-hydroxynaphthyl), have very similar structures to (4), but those of others (R = Ph, R′= 4-hydroxynaphthyl and R = C6H11, R′= 2-hydroxy-5-methylphenyl) are different. The data suggest a molecular structure for the 4-hydroxynaphthyl compound in which the tin is chelated by one carboxyl oxygen atom and a nitrogen atom with a meridional-SnC3ON geometry, and a weakly carboxylato-bridged chain structure for the cyclohexyl compound.

The crystal and molecular structure of adamanta-(µ4-oxo-hexakis(µ-triphenylsiloxy)-tetralead(II)

The crystal and molecular structure of the title compound, [Pb4(OSiPh3)6O], obtained from the reaction of triphenylsilanol and bis(cyclopentadienyl) lead(II), is described.

Structural studies in main group chemistry : XXVI. The structure of O-trimethylstannyl-n-phenyl-n-benzoylhydroxylamine

Abstract The structure of the title compound has been determined by Patterson and Fourier methods from four-circle diffractometer data to a final “R”-value of 0.0353 using 2792 independent non-zero reflections. Crystal;s are monoclinic, space group P21 1 with a  10.778(4), b  17.083(8), c  10.399 (4) A, β  120.79(7)°, Z  2. The asymmetric unit of Me 3 Sn[ON(Ph)COPh] consists of two crystallographically independent, non-interacting molecules, both of which posses distorted “local” trigonal-bipyramidal cis -[SnC 3 O 2 ] geometry. In one molecule, the axial SnC bond is significantly longer (2.22(2) A) than the two equatorial SnC distances (mean 2.04)A), whilst in the other converse pertains, the equatorial SnC distances being marginally longer (mean 2.18(1) A) than the axial SnC distance (2.16(1) A)than the axial SnC distance (2.16(1) A). In both molecules, the axial coordinate SnO bond is longer than the equatorial Sn O bond (2.263(6) A vs 2.152(6) A; 2.392(6) A vs. 2.064(6) A.

Structural studies in main-group chemistry. Part VI. Crystal and molecular structure of 2,2′-bipyridyldichlorodiphenyltin

The crystal structure of the title compound has been determined by single-crystal X-ray diffraction. Crystals are monoclinic, space group P21/n, with Z= 4 in each unit cell of dimensions a= 9·5208(24), b= 13·1583(36), c= 16·5437(40)A, β= 93·600(17)°. The structure was solved by the heavy-atom method and refined by full-matrix least-squares methods to R 0·049 for 1896 independent reflections. The tin atoms are octahedrally co-ordinated by a bidentate 2,2′-bipyridyl residue, two cis-chlorine atoms, and two phenyl groups which are mutually trans. The two tin–carbon bond distances are identical [mean r(Sn–C) 2·152 A], as are the two tin–chlorine bond distances [mean r(Sn–Cl) 2·509 A]. The bipyridyl group is not planar, one C5H4N ring being twisted 4·2° with respect to the other, with the two Sn–N distances unequal (2·344 and 2·375 A). The bond angles subtended at tin by adjacent ligands all fall in the range 85·5–95·6°. The two phenyl groups are not exactly trans(C–Sn–C 173·5°), and are not equivalent. The plane of one phenyl group almost exactly bisects the Cl–Sn–Cl and N–Sn–N bond angles, whilst the other is rotated 79·5° with respect to the first.