The synthesis and room-temperature single-crystal X-ray structure determination are recorded for a 1:1 adduct of lead(II) thiocyanate with pyridine (' py '). [( py ) Pb (SCN)2](∞|∞) is triclinic, Pī , a 10.544(1), b 7.3729(7), c 6.705(2) Ǻ, α 103.91(2), β 95.99(2), γ 100.51(1)°, Z = 2 f.u .; R was 0.041 for 3226 'observed' (I > 3σ(I)) reflections. The structure is a two-dimensional polymer in the be plane with eight-coordinate ( py -N)PbN3S4 linked by the familiar four- membered Pb2S2 and eight-membered Pb2(NCS)2 motifs by way of bridging thiocyanate groups; one of the latter, unusually, has a bifurcating bridging nitrogen atom leading to the introduction of Pb2N2 motifs. The structure of the parent lead(II) thiocyanate is also discussed.

Extraction of the sponge Aplysilla sulphuvea (Order, Dendroceratida) yielded two crystalline substances, aplysulphurin, C2ZH2805, and aplysulphuride, C22H32O5 Chemical and spectroscopic evidence suggested that aplysulphurin, the title compound, had the structure (2). This was confirmed by a single-crystal X-ray determination.Aplysulphurin, a neutral, optically active substance, was shown to have the molecular formula, C22H2805, by elemental analysis and mass spectrometry. The highest peak in the electron impact mass spectrum was at m/z 328 because of loss of CO, from the molecular ion, but in the chemical ionization spectrum a [M +H] ion was evident at m/z 373, corresponding to a molecular weight of 372. Nine units of unsaturation were therefore present.The lH n.m.r. spectrum (100 MHz) showed an AB quartet at 6 7.36, 7.52 ( J 8 . 2 Hz), consistent uith two protons attached ortho to a tetrasubstituted benzene ring; a benzene ring was also suggested by the ultraviolet spectrum (A,,, 263 nm, E 300) and by the 13C n.m.r. spectrum [four singletsW at 6 131.7, 133.3, 137.8 and 148.7, and 2 doublets* at 122.3 and 129.2 (l J,, 166 and 158 Hz respectively in the fully coupled spectrun~)]. The data showed that all substituents of the ring were saturated carbon atoms.The infrared spectrum showed two ester carbonyl absorptions, at 1758 and 1741 cm-' (confirmed by 13C 6 170.7,169.6). Absorption at 1236 cm-I and a three-proton singlet at S 2.16 in the 'H n.m.r, spectrum substantiated the presence of an acetoxy group (v,, 1741 cm-'). The e.i. mass spectrum showed a loss of ketene from the ion * Multiplicity in single frequency off-resonance decoupled spectra.

The isolation of two new sesquiterpenes (3) and (8) and a novel nor sesquiterpene (16) from Lemnalia africana is reported. In each case, the absolute stereochemistry was deduced chemically and spectroscopically, and confirmed by a single-crystal X-ray study on a suitable derivative (7).

Syntheses and single-crystal X-ray structural characterizations (at c. 295 K) are recorded for the 1 : 1 adducts of copper(I) chloride, bromide and iodide with L = 2,2′-bipyridine. The chloride is triclinic, Pī , a 14.069(5), b 10.520(3), c 7.872(2)Ǻ, α 69.00(2), β 88.62(3), γ 70.70(2)°, Z = 4 formula units; R was 0.041 for No 1805 'observed' [I > 3σ(I)] reflections. The bromide is monoclinic, P21/c, a 8.788(3), b 13.206(6), c 9.895(3)Ǻ, β 117.90(2)°, Z = 4 formula units; R 0.036 for No 1007. The iodide is monoclinic, C2/c, a 17.571(3), b 8.587(7), c 16.796(3)Ǻ, β 120.17(2)°, Z = 8 formula units; R 0.041 for No 1038. The chloride is ionic, [CuL2]+ [ ClCuCl ]-; in the cation, Cu-N are 2.005(6)-2.039(6)Ǻ with interligand N-Cu-N 114.4(3)-132.4(2)°, while, in the anion, Cl-Cu-Cl is 177.3(1)°, with Cu-Cl 2.086(2) and 2.091(2)Ǻ. The bromide (unlike its 1,10-phenanthroline counterpart, which is ionic) is a centrosymmetric dimer , as also is the iodide. In the bromide, Cu-N are 2.083(6), 2.099(5), and Cu-Br 2.428(2), 2.463(1)Ǻ, Cu…Cu and Br…Br being 2.850(1) and 3.975(2)Ǻ respectively. In the iodide, Cu-N are 2.070(8), 2.08(1), and Cu-I, 2.583(3)Ǻ (×2), and Cu…Cu and I…I are 2.610(2) and 4.420(1)Ǻ.

The structure and absolute configuration of (-)-bukittinggine (1), the major alkaloid isolated from the leaves of Sapium baccatum ( Roxb.) Ridley ( Euphorbiaceae ) have been determined from the crystal structure of its hydrobromide. Diffractometer data at 295 K were refined by least-squares techniques to a residual of 0.040 (3150 'observed' reflections). Crystals of bukittinggine hydrobromide are orthorhombic, P212121, a 14.947(4), b 14.580(4), c 8.801(2)Ǻ, Z4.