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The reactivity of the silylated sterically hindered thiolates [C6H4SH-2-SiPh3] and [C6H4SH-2-SiCH3Ph2] has been examined with transition metal complexes of group 10. A series of palladium(II) and platinum(II) complexes were obtained. Analysis of these complexes by different spectroscopic techniques and single crystal X-ray diffraction studies revealed the formulations to be dependent of the stoichiometry and relative size of the metal center and thiolate. Analogous reactions with nickel complexes afforded oxidation decomposition products.

Copper(II) complexes of three chiral enantiomeric pairs of o-hydroxy Schiff bases derived from (R)-(−)-secbutylamine and (S)-(+)-secbutylamine, were prepared and characterized by i.r., electronic, cd, epr and mass spectra. Some X-ray crystal structures were obtained. The X-ray study of five complexes shows that the geometry around the metal atom is pseudotetrahedral. Additionally, epr studies of all these complexes in dmf solution at 77 K suggest that their geometry in liquid phase is slightly different to that observed in solid state by X-ray crystallography. Even though, cd spectra only show charge transfer absorptions, the data confirm the enantiomeric pair character of the obtained complexes.

A series of palladium fluoro-aniline complexes of the trans -[PdCl 2 (NH 2 Ar F ) 2 ] type were synthesized in good yields by direct reaction of trans -[PdCl 2 (C 6 H 5 CN)] with Ar F NH 2 ; Ar F = C 6 H 3 -2,3-F 2 ( 1 ), C 6 H 3 -2,5-F 2 ( 2 ), C 6 H 3 -3,4-F 2 ( 3 ), C 6 H 3 -3,5-F 2 ( 4 ), C 6 H 2 -2,3,4-F 3 ( 5 ), C 6 H 2 -2,3,6-F 3 ( 6 ), C 6 H 2 -2,4,5-F 3 ( 7 ), C 6 H 2 -2,4,6-F 3 ( 8 ), C 6 F 4 -4-H ( 9 ), C 6 F 5 ( 10 ). The crystal structures of complexes 3 , 4 and 5 were determined. Heck coupling reactions were carried out using complexes 1–10 as catalysts in order to examine the effect of the fluorinated anilines in the reaction of bromobenzene and styrene.

The synthesis of bis-imino nickel(II) NNN pincer complexes of the type [NiCl 2 {C 5 H 3 N-2,6-(CHNAr f ) 2 }]; Ar f =C 6 H 3 -2,3-F 2 (1), C 6 H 3 -2,5-F 2 (2), C 6 H 3 -3,4-F 2 (3), C 6 H 3 -3,5-F 2 (4), C 6 H 2 -2,3,4-F 3 (5), C 6 H 2 -2,3,6-F 3 (6), C 6 H 2 -2,4,5-F 3 (7), C 6 H 2 -2,4,6-F 3 (8), has been achieved and their reactivity in alkyl- and arylthiolation reactions of halobenzenes examined. The use of fluorinated substituents Ar f on the imines has allowed the tuning of the electronics in these complexes and the influence of these substituents and those of the disulfides in the thiolation reactions have been analyzed.

Diferrocenyl(methylthio)cyclopropenylium iodide reacts with organometallic compounds (methyllithium, benzyl- and ethylmagnesium chlorides, and allylmagnesium bromide) to yield 2,3-diferrocenyl-1-methylthio-1,3-dienes or -1,3,5-triene together with 3,3-dialkyl-1,2-diferrocenylcyclopropenes. We present data from X-ray diffraction analyses of (E)-2,3-diferrocenyl-1-methylthio- and (E,Z)-2,3-diferrocenyl-1-methylthio-4-phenyl-1,3-butadienes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The synthesis of bis-imino nickel(II) NNN pincer complexes of the type [NiCl2{C5H3N-2,6-(CHNArf)2}]; Arf = C6H3-2,3-F2 (1), C6H3-2,5-F2 (2), C6H3-3,4-F2 (3), C6H3-3,5-F2 (4), C6H2-2,3,4-F3 (5), C6H2-2,3,6-F3 (6), C6H2-2,4,5-F3 (7), and C6H2-2,4,6-F3 (8), has been achieved and its reactivity explored proving these compounds to be efficient in the alkyl and aryl thiolation of iodobenzene.

A series of palladium thiolate complexes of the [Pd(Ph2PC6H4-2-(CH2NMe2))(SRF)2] type have been synthesized in good yields by metathetical reactions of [Pd(Ph2PC6H4-2-(CH2NMe2))Cl2] (1) with [Pb(SRF)2], (SRF = S − C6F5, S − C6F4-4-H, S − C6H4-2-CF3, S − C6H4-4-F, S − C6H4-2-F) and their crystal structures determined. Heck coupling reactions were carried out using [Pd(Ph2PC6H4-2-(CH2NMe2))(SRF)2], SRF = S − C6F5 (2), S − C6F4-4-H (3), S − C6H4-2-CF3 (4), S − C6H4-4-F (5), S − C6H4-2-F (6) complexes as catalysts in order to examine the effect of the thiolates in the reaction of bromobenzene and styrene. The results obtained indicate that the less electron-withdrawing substituents on the thiolate moiety may favor higher yields in the Pd catalyzed Heck reaction using [Pd(Ph2PC6H4-2-(CH2NMe2))(SRF)2] as catalysts.

A series of palladium thiolate complexes of the type [Pd(dppf)(SRF)2] have been synthesized in good yields by metathetical reactions of [Pd(dppf)Cl2] with [Pb(SRF)2], (SRF=−SC6F5, −SC6F4-4-H, −SC6H4-2-CF3, −SC6H4-4-F, −SC6H4-3-F) and their crystal structures determined. The effect of the different thiolates in the structural properties of the complexes both in the solid state and in solution have been analyzed. Heck coupling reactions were carried out using the complexes [Pd(dppf)(SRF)2], SRF=−SC6F5 (1), −SC6F4-4-H (2), −SC6H4-2-CF3 (3), −SC6H4-4-F (4), −SC6H4-3-F (5) as catalysts in order to examine both the effect of the thiolates and the P–Pd–P bite angles in the reaction of bromobenzene and styrene. The results obtained indicate that electron-withdrawing substituents may favor higher yields in the Pd catalyzed Heck reaction using [Pd(dppf)(SRF)2] as catalysts.

A series of intramolecular condensation products were obtained by base-catalyzed treatment of the natural bioactive dimeric phthalide diligustilide (1) using different reaction conditions and the yields remarkably depend on these. The reaction conditions to obtain selectively the intramolecular condensation derivatives or the hydrolysis products of diligustilide (1) are described.

The complex [RuCl 2 (CO)(DMF)(PPh 3 ) 2 ], was easily synthesized in high yield from [RuCl 2 (PPh 3 ) 3 ] and DMF as source of CO. The carbonylated specie has been characterized by X-ray structural analysis.

The reactions of [Sn(Ph)2(Ph2PC6H4-2-S)2] with trans -[M(Cl)(CO)(PPh3)2] M=Ir, Rh afford the complexes [Rh(Ph2PC6H4-2-S)2(SnClPh2)] (1) and [Ir(CO)(Ph2PC6H4-2-S)2(SnClPh2)] (2) as final products of two processes, a transmetallation reaction and an oxidative addition process. The crystal structures of both complexes have been determined, showing the rhodium compound to be into a slightly distorted square base pyramidal geometry, while that of the iridium derivative can be described as a distorted octahedron.

In solution, allyl palladium homobimetallic complexes bridged by fluorinated benzenethiolates, [{Pd(μ-SR)(η3-C3H5)}2] where R=C6F5, 1; C6HF4-4, 2; C6H4F-2, 3; C6H4F-3, 4 and C6H4F-4, 5, are found as a mixture of syn/anti and cis/trans isomers. The variable temperature 1H and 19F NMR study of these compounds show that the four isomers undergo interconversion through two probable mechanisms, allyl rotation assisted by the solvent and inversion of the configuration at the sulphur atoms. The X-ray crystal structure determination of [{Pd(μ-SC6F5)(η3-C3H5)}2] and [{Pd(μ-S C6HF4-4)(η3-C3H5)}2] shown both complexes to be bimetallic with the metal centres found in a slightly distorted square planar environments.

The complexes cis -[M(Ph 2 PC 6 H 4 -2-S) 2 ] M=Ni, Pd, Pt were stereoselectively synthesized by transmetallation reactions of [M(Cl) 2 (NCC 6 H 5 ) 2 ] M=Pd, Pt or NiCl 2 ·6H 2 O with [Sn(R) 2 (Ph 2 PC 6 H 4 -2-S) 2 ] R=Ph, n Bu or t Bu. The conformation of the Pd and Pt derivatives being unequivocally confirmed by single crystal X-ray diffraction studies showing both metal centers to be into a slightly distorted square planar environment, the main distortion being due to the steric hindrance caused by the aromatic rings in the phosphine moiety.

The title ethylene ketal 1, C23H23F2NO2, has a tricyclic azaadamantane cage with aryl rings (4-fluorophenyl) substituted at the 2 and 9 positions. Rings A (C11–C16) and B (C17–C22) are attached to atoms C2 and C9 in axial and equatorial positions, respectively; and the presence of the five-membered 1,3-dioxolane ring attached to atom C4. The structural analysis of the title was carried out by experimental (single crystal X-ray diffraction and NMR) and confirmed by theoretical calculations (ab initio RHF, DFT and NMR-DFT-GIAO).

The synthesis of dimethyl {2-[3-(4-nitrophenyl)-1 H -pyrazol-5-yl]ethyl}malonate monohydrate 1 , C 16 H 17 N 3 O 6 ·H 2 O was performed and the molecular structure has been studied by using NMR, single crystal X-ray diffraction and ab initio calculations. The title compound presents a pyrazole ring (N1 to C5), a phenyl ring (C1″ to C6″) attached to C3 and the ethylene dimethyl malonate frame (C1′ to C7′) attached to C5. The torsion angle defined by N2C3C1″C2″ (−12.26°) showed that pyrazole and phenyl rings are not in the same plane. Monohydration in ( 1 ) is present in the structure by a NH⋯OH 2 hydrogen bonding, with a bond length of 1.782 A. Experimental and theoretical evidences indicated the preference of the 3-tautomer over the corresponding 5-tautomer in the titled pyrazole.

Thermal reactions of [M(CO)6] with 1,2,3,4-tetrahydroquinoline (1) afford the corresponding (η6-arene)tricarbonylmetal complex (M=Cr, 3; M=Mo, 4; and M=W, 5). In contrast, thermolysis of the same hexacarbonyl complexes with 1,2,3,4-tetrahydroisoquinoline (2) affords the (σ-nitrogen)pentacarbonylmetal derivatives (M=Cr, 7; M=Mo, 8; and M=W, 9). For chromium the (η6-arene)tricarbonylmetal complex (6) was also isolated. X-ray crystal structures are reported for 3, 4, 7 and 9.

The reactivity of the hybrid phosphorus–sulfur proligand phPS2H2 with the trans-[Pd(Cl)2(PPh3)2] precursor has been explored. By reacting trans-[Pd(Cl)2(PPh3)2] with phPS2H2 in the presence of NEt3 as base, the complex [Pd(phPS2)(PPh3)] was obtained. A single crystal X-ray structure determination for [Pd(phPS2)(PPh3)] shown the compound to be square planar with the ligand phPS2 behaving as a SPS pincer ligand.

Reaction of 4-formylantipyrine with N(4)-dimethylthiosemicarbazide and 3-piperidylthiosemicarbazide produces the N(4)-dimethylthiosemicarbazone (1), and the 3-piperidyl-thiosemicarbazone (2), respectively. Compound 1 is triclinic, space group P-1 with a = 6.329(1) A, b = 11.699(1) A, c = 11.943(1) A, α = 65.83(1)°, β = 80.83(1)°, γ = 84.90(1)°, and V = 796.1(1) A3 with Z = 2, for Dcalc = 1.324 g/cm3. Compound 2 is triclinic, space group P-1 with a = 6.784(1) A, b = 10.485(2) A, c = 13.462(3) A, α = 102.05(2)°, β = 98.61(2)°, γ = 101.32(2)°, and V = 899.8(5) A3 with Z = 2, for Dcalc = 1.319 g/cm3. Reaction of 4-aminoantipyrine with phenyl isothiocyanate produced N-antipyrine-N′-phenylthiourea (3). Compound 3 is monoclinic, space group P21/n with a = 6.863(7) A, b = 15.361(3) A, c = 16.332(5) A, β = 90.35(6)°, and V = 1720.7(18) A3 with Z = 4, for Dcalc = 1.306 g/cm3. Compounds 1 and 2 have intermolecular hydrogen bonding between the carbonyl oxygen of the antipyrine moiety and the NH hydrogen of the thiosemicarbazone moiety. In 3 the two unique molecules are held together as a dimer by interactions of the two thiourea NH's and the antipyrine moiety's\break oxygen.

N-2-(3-picolyl)-N′-phenylthiourea, 3PicTuPh, monoclinic, P21/n, a=7.617(2) b=7.197(5), c=22.889(5) A, β=94.63(4)°, V=1250.7(1) A3 and Z=4; N-2-(4-picolyl)-N′-phenylthiourea, 4PicTuPh, triclinic, P-1, a=7.3960(5), b=7.9660(12), c=21.600(3) A, α=86.401(4), β=84.899(8), γ=77.769(8)°, V=1237.5(3) A3 and Z=4; N-2-(5-picolyl)-N′-phenylthiourea, 5PicTuPh, monoclinic, P21/c, a=14.201(1), b=4.905(3), c=17.689(3) A, β=91.38(1)°, V=1231.8(7) A3 and Z=4; N-2-(6-picolyl)-N′-phenylthiourea, 6PicTuPh, monoclinic, C2/c2, a=14.713(1), b=9.367(1), c=18.227(1) A, β=92.88(1)°, V=2515.5(1) A3 and Z=8 and N-2-(4,6-lutidyl)-N′-phenylthiourea, 4,6LutTuPh, monoclinic, C2/c, a=11.107(2), b=11.793(2), c=20.084(4) A, β=96.10(3)°, V=2616(1) A3 and Z=8. Intramolecular hydrogen bonding between N′H and the pyridyl nitrogen and intermolecular hydrogen bonding involving the thione sulfur are affected by substitution of the pyridine ring, as is the planarity of the molecule. 1H NMR studies in CDCl3 show the NH′ hydrogen resonance considerably downfield from other resonances in the spectrum for each thiourea.

Two dithiocarbamate derivatives of stannolane, 2-nbutyl-2-(dimethyldithiocarbamate)-1,3,2-oxathiastannolane and 2-nbutyl-2-(piperidyldithiocarbamate)-1,3,2-oxathiastannolane have been obtained and full characterized. The X-ray single crystal diffraction studies show the presence of a dimer arrangement, through the formation of an inorganic ring. The bond lengths between the tin and all the S and O atoms are in the middle of covalent and secondary bonds, with a remarkable preference toward oxygen atoms. Both oxathiastannolane units present in solid state an equilibrium between conformations, while the arrangement of the three fused rings (oxathiastannolane–distannoxane–oxathiastannolane) is almost planar.

Three copper(II) complexes derived from bulky ortho-hydroxy Schiff base ligands, (1)–(3), were synthesized and characterized by chemical analysis, UV–Vis, IR, μeff and mass spectrometry. The solid state structures of compounds (1)–(3) were determined. The solid state X-ray diffraction studies of these compounds show that the geometry is intermediate between square planar and tetrahedral. Moreover, EPR studies in DMF solution at 77 K suggest that the geometry of these complexes in solution is different from that observed in the solid state by X-ray crystallography. Furthermore, cyclic voltammetry studies performed for (1)–(3), indicate a dependence of the cathodic potentials upon conformational and electronic effects.

Condensation of aminoguanidine with 2-formylpyridine, 2-benzoylpyridine and 2,6-diacetylpyridine results in the aminoguanidones, HFogu, HBzgu and H22,6Acgu2, respectively. Reaction of the heterocyclic aminoguanidone in a mixture of hydrochloric acid–ethanol with copper(II) chloride produces the following mixed salts: [H3Fogu][CuCl4], (1), [H3Bzgu]2 [CuCl4]Cl2·H2O, (2), and [H52,6Acgu2][CuCl4]Cl·H2O, (3). Their crystal structures, as well as their ESR and UV spectra, have been obtained. The influence on the geometry of the [CuCl4]2− of the NH⋯ClCu hydrogen bonds, in the context of charged compensation hypothesis, has been evaluated.

The synthesis and characterization of the pentacoordinated butanoylsalophencobalt(III) compound, including X-ray analysis, are described. The chemical shift in the 13C-n.m.r. of the carbonyl carbon was determined by means of an HMBC experiment. Collision induced dissociation (CID) and high resolution mass spectrometry were used to establish the fragmentation pattern of the CoC24H21N2O3 compound. X-ray diffraction analysis shows the presence of two conformations for the acylsalophen ligand system in the same monocrystal, as well as two different OċċċH–C hydrogen bonds with unusual interactions.

Reactions of 2-aminopicolines with 2- and 4-tolyl isothiocyanates yielded N-2-(4-picolyl)-N′-4-tolylthiourea, 1, N-2-(3-picolyl)-N′-4-tolylthiourea, 2, and N-2-(4-picolyl)-N′-2-tolylthiourea, 3. Compound 1 is monoclinic, of space group P21/c with a = 7.456(1) A, b = 13.135(3) A, c = 13.959(3) A, β = 104.99(3)°, and V = 1320.5(5) A3 with Z = 4, for d calc = 1.294 g/cm3. Compound 2 is triclinic, of space group $$P\bar 1$$ with a = 6.877(3) A, b = 7.590(5) A, c = 13.213(9) A, α = 78.38(2)°, β = 77.96(4)°, γ = 86.36(4)°, and V = 660.5(7) A3 with Z = 2, for d calc = 1.294 g/cm3. Compound 3 is monoclinic, of space group P21/c with a = 12.604(2) A, b = 15.592(3) A, c = 6.875(2) A, β = 91.05(2)°, and V = 1350.9(2) A3 with Z = 4, for d calc = 1.265 g/cm3. The three thioureas are found in both solid state and solution in a conformation resulting from intramolecular $${\text{N}}{\kern 1pt} ---{\kern 1pt} {\text{H}} \cdot \cdot \cdot {\text{N}}$$ hydrogen bonding. Compounds 1 and 3 present an intermolecular hydrogen bond involving the thione sulfur and the NH hydrogen, which is not present in 2 owing to the steric hindrance of the methyl group in the phenyl ring. The geometry of the molecule is affected by the position of the methyl groups on the pyridine and aryl rings.

A new cacalolide sesquiterpenoid, named as Romo-A, was isolated from the roots of Psacalium decompositum , Asteraceae, a Mexican medicinal shrub with antidiabetic properties. Its structure was elucidated by NMR, MS, IR, UV, and confirmed by X-ray diffraction studies.

The synthesis of monomeric pentacoordinated diorganotin(IV) complexes derived from pyridoxal hydrochloride and 4- or 5-R-substituted ortho-aminophenols is described. The complexes were characterized using UV–visible, infrared, mass, 1H NMR, 13C NMR and 119Sn NMR spectral techniques. The molecular structure of three complexes was established using X-ray diffraction: 3b and 3d show a distorted trigonal bipyramidal geometry, in which the basal plane is defined by the butyl groups and the iminic nitrogen atom, whereas the oxygen atoms from the aromatic ring occupy axial positions; in contrast, complex 3e exhibits a square pyramidal geometry. The cytotoxic activity of all complexes against human cell lines U-251 (glioblastoma), K-562 (chronic myelogenous leukemia), HCT-15 (human colorectal cancer), MCF-7 (human breast cancer) and SKLU-1 (non-small-cell lung cancer) was evaluated, and the inhibitory percentage values indicated higher activity than the reference standard, cisplatin. Acute toxicity studies were performed in vivo for the prepared complexes to determine the lethal medium dose (LD50) after intraperitoneal administration to mice.

The syntheses of PIN as well as an S-Ph-analogue are described and their structures are confirmed by X-ray analysis.

Vismia mexicana (Clusiaceae) is a small tropical tree found from Mexico to Honduras. The CH2Cl2=MeOH extract from the leaves has been reported to have inhibitory properties against reverse transcriptase of human immunodeficiency virus type 1 (HIV-1 RT). In order to characterize some of its chemical constituents, the EtOAc-soluble fraction of this extract was subjected to column chromatography. A new natural product was isolated and designated vismiaquinone D [1-hydroxy-6- methoxy-7,8-(3',3'-dimethyl-pyrano) anthraquinone]. In addition, vismiaquinone was obtained. The structures of vismiaquinone and vismiaquinone D were determined by 1H and 13C NMR spectroscopy, unambiguous assignments were achieved with DEPT, HSQC, and HMBC experiments, and corroborated by X-ray diffraction studies. The isolated anthraquinones were tested against HIV-1 RT. However, none showed relevant activity, suggesting that other compounds in this extract may be responsible for its HIV-1 RT inhibitory properties.

The asymmetric unit of the title compound, [PdCl2(C10H8N2)]·0.5C4H8O2, consists of one PdIIcomplex molecule and a half-molecule of 1,4-dioxane, the complete molecule being generated by inversion symmetry. The PdIIatom has an almost square-planar coordination formed by the 2,2′-bipyridine ligand and two chloride ligands. Two intramolecular C—H...Cl hydrogen bonds occur. In the crystal, the PdIIcomplex and 1,4-dioxane molecules are connected by C—H...O hydrogen bonds, forming a layer parallel to (10-1). Within the layer, weak π–π interactions [centroid–centroid distance = 3.817 (4) Å] are observed between the pyridine rings.

From the fermentation mycelium of the endophytic fungus Edenia gomezpompae were obtained several phytotoxic compounds including two new members of the naphthoquinone spiroketal family, namely, palmarumycin EG1 (1) and preussomerin EG4 (4). In addition, preussomerins EG1–EG3 (7–9) and palmarumycins CP19 (2), CP17 (3), and CP2 (6), as well as ergosta-4,6,8(14),22-tetraen-3-one (5), were obtained. Compounds 2, 3, and 5 are new to this species. The structures of palmarumycins CP19 (2) and CP17 (3) were unambiguously determined by X-ray analysis. The isolates and mycelium organic extracts from four morphological variants of E. gomezpompae caused significant inhibition of seed germination, root elongation, and seedling respiration of Amaranthus hypochondriacus, Solanum lycopersicum, and Echinochloa crus-galli. The treatments also affected respiration on intact mitochondria isolated from spinach.

In the cation of the title molecular salt, C6H16NO+·Cl−, the N—C—C—O torsion angle is 176.5 (2)°. In the crystal, the cations and chloride ions are linked by N—H...O and O—H...O hydrogen bonds, generating a two-dimensional network parallel to (100).

A complete series of dppfMX2 (M=Pt, Pd; X=Cl, Br, I) compounds have been synthesized using different routes, and characterized fully. The synthesis of dppfPdI2 has been achieved by reacting Pd(COD)Cl2 with dppf in the presence of NaI. X-ray structures of dppfPdBr2 and dppfPdI2 have also been reported for the first time in this study. A preliminary Suzuki coupling screening study reveals that dppfPdX2 compounds are superior to the conventional Ph3P-based catalysts and bidentate phosphine-based ligands. Reactions carried out under in situ conditions also gave a similar trend, but their respective activities were much lower than that of the fully formed catalysts.

Only recently have noncovalent interactions (notably hydrogen bonds) been used in deliberate strategies for connecting coordination complexes into extended networks. The significance of such intermolecular forces is further demonstrated in this structural study of four different 1,8-bis(dimethylamino)naphthalenium, [HDMAN]+, halo-metalates. The cation is unable to engage in any strong hydrogen-bond interactions and the resulting structures do not display any repeating topologies or motifs. This is in stark contrast with previous work on halo-metalates with cations capable of forming directional hydrogen bonds, e.g., 4,4-bipyridinium(2+); those structures contain charge-assisted MX...HN+ interactions between anions and cations resulting in well-defined 1-D and 2-D motifs. The [HDMAN]+ structures presented here, however, are determined by close-packing principles; no repeating motifs are observed, which emphasizes that hydrogen bonding is an effective tool for directed assembly of substantial coordination c...

The synthesis of the organotellurium(IV) compounds [C4H8TeI(S2PMe2)] (2), [C4H8TeI(S2PEt2)] (3), [C4H8TeI(S2CNC4H6)] (4) and [C4H8TeI(SOCNC5H10)] (6) was achieved. All of them were characterized by IR, 1H-, 13C-, 31P- and 125Te-NMR, mass spectroscopy, elemental analyses and single-crystal X-ray diffraction. In addition, the crystal and molecular structures of the previously known 1,1-diiodotetrahydrotellurophene and [C4H8TeI(S2CNEt2)] (5) were obtained. The geometry around Te(IV) is that of a sawhorse structure in which the lone pair is apparently stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. All the structures exhibit different supramolecular associations. The intermolecular Te⋯S and Te⋯I interactions result in the formation of dimeric species in 4, and in 1 and 6, respectively. The intermolecular Te⋯S bonds in 2, 3 and 5 lead to formation of one-dimensional polymers.

Six Schiff base copper(II) complexes have been prepared and characterized, elemental analyses, mass, IR and electronic spectra, μeff and X-ray crystal structures being obtained. The X-ray study shows that the geometry around the metal atom is square planar for one of the complexes only and distorted square planar for the others. Electrochemical studies on the complexes, though revealing a dependence of the Cu(II)/Cu(I) potentials on electronic effects, also show that these are independent of the structure observed in the solid state. Besides, EPR studies of these complexes in DMF solution at 193 K suggest that the geometry of these complexes in solution is different to that observed in the solid state by X-ray crystallography.

The crystal structure of 2,4,6,8-tetra-t-Bu-phenothiazine 0.5C6H6 (Pnma space group, a=11.685, b=25.593, c=10.339) shows short intermolecular t-Bu(CH3)⋯Ph and CH3⋯CH3 contacts which allow the formation of well defined channels along the a direction. These channels host one benzene molecule for each pair of phenothiazine molecules. AM1 molecular orbital calculations suggest that there is a strong coupling of the t-Bu groups rotations and the folding of the ring and this in turn makes the phenothiazine skeleton to be less folded than expected from the presence of four electron donating substituents.

N -(2-pyridylethyl)- N ′-phenylthiourea, triclinic, P-1, a=8.616(1) A , b=9.663(1) A , c=9.761(1) A , α =102.05(1)°, β =102.36(1)°, and γ =116.17(1)°, V=668.5(1) A 3 , Z =2, μ=2.022 mm −1 , N -(2-pyridylethyl)- N ′- p -tolylthiourea, triclinic, P-1, a=8.804(3) A , b=9.951(2) A , c=10.255(2) A , α =115.03(2)°, β =105.93(2)°, γ =104.04(2)°, V=713.43(1) A 3 , Z =2, μ=2.173 mm −1 , N -(2-pyridyl-ethyl)- N ′- p -bromophenylthiourea, triclinic, P-1, a=9.536(1) A , b=9.809(1) A , c=10.042(2) A , α =115.88(1)°, β =96.80(1)°, and γ =110.44(1)°, V=750.0(6) A 3 , Z =2, μ=28.73 mm −1 , N -(2-pyridyl-ethyl)- N ′- p -nitrophenylthiourea, triclinic, P-1, a=8.046(2) A , b=8.602(3) A , c=10.938(3) A , α =80.74(3)°, β =89.77(2)°, γ =77.00(3)°, V=727.6(6) A 3 , Z =2, μ=2.325 mm −1 and N -(2-pyridylethyl)- N ′- p -methoxyphenylthiourea, monoclinic, P2 1 /n, a=11.526(2) A , b=9.723(2) A , c=13.460(2) A , β =100.49(2)°, V=1483.3(2) A 3 , Z =4, μ=1.929 mm −1 . All five molecules possess an intramolecular hydrogen bond between NH and the pyridyl nitrogen, as well as intermolecular hydrogen bonding between N′H and a thione sulfur of a second molecule to form centrosymmetric dimers. Solution 1 H NMR studies (CDCl 3 ) show the N′H resonance downfield for each thiourea and its shift, as well as that of NH, is affected by substituents on the phenyl ring.

The reaction of nBuSnCl3 and the sodium salt of 2-mercaptoethanol (1:1) in ethanol gave the compound Sn(nBu)(Cl)[(OCH2CH2S)2Sn(nBu)]2 (1). [(nBu)Sn(SCH2CH2O)SCH2CH2OH] (2) was initially isolated from the reaction of 1 with nBuMgCl as a rearrangement product but was also synthesized from nBuSn(O)OH and two molar equivalents of 2-mercaptoethanol. Both compounds were characterized by means of IR, 119Sn, 13C, and 1H NMR, FAB mass spectroscopy, and elemental analyses. The structures were determined by single-crystal X-ray diffraction. 1 crystallizes in the monoclinic Cc space group (a = 18.492(3) A, b = 17.329(2) A, c = 10.787(1) A, beta = 111.88(1) degrees, Z = 4), while 2 crystallizes in the orthorhombic Pbca space group (a = 14.458(2) A, b = 10.393(1) A, c = 16.479(2) A, Z = 8). 1 is a trimetallic Tin(IV) compound in which the central atom is in 6-fold coordination, while the two remaining tin atoms show 5-fold coordination. Both pentacoordinated tin atoms are bonded to a butyl group and to the oxygen and the sulfur atoms from two [OCH2CH2S]2- ligands forming two stannolanes, which are fused with the hexacoordinated tin atom forming a distannoxane system. This arrangement is quite different from previous ladder or staircase structures. NMR data point to maintenance of this structure in solution. 2 consists of [(nBu)Sn(SCH2CH2O)(SCH2CH2OH)] units, which are associated via intermolecular Sn-O interactions building up a dimer. The tin atom forms two "stannolane" units by interaction with [OCH2CH2S]2- and [HOCH2CH2S]- ligands.

The multidentate ligand, 2,6-diacetylpyridine bis(3-hexamethyleneiminylthiosemicarbazone) monohydrate, H22,6Achexim·H2O, crystallizes with one thiosemicarbazone moiety in an intramolecular hydrogen bonded, bifurcated E′ form. The other thiosemicarbazone moiety is E and is not involved in intramolecular hydrogen bonding, but is involved in hydrogen bonding with the hydrate water molecule. The dianion (loss of N3a and N3b hydrogens) of H22,6Achexim acts as a pentadentate ligand, 2,6Achexim, in a planar conformation to a central tin(IV) ion, and as a bridging tetradentate ligand with the two thiosemicarbazone moieties of 2,6Achexim coordinating to different zinc atoms. The tin(IV) is heptacoordinate in a distorted pentagonal dipyramidal configuration, with the five SNNNS donor atoms of 2,6Achexim in the pentagonal plane and the two n-butyl groups in the axial positions. The binuclear zinc complex has two equivalent tetrahedral zinc centers, with the pyridyl nitrogens of the two ligands not coordinated.

Two novel compounds, celastroidine A (1) and B (2), were isolated from the roots of Hippocratea celastroides K. Their structures were elucidated by spectroscopical and X-ray diffraction studies. Celastroidine A (1) (C50H74O5) was identified as a Diels-Alder adduct of a triterpene plus a diterpene and celastroidine B (2) as a beyerane, a type of dimer of two diterpene (C40H60O4). Both compounds could be formed in vivo by a Diels-Alder reaction. Celastroidine A showed some antifeeding activity against the stored grain insect Sitophyllus zeamays.Key words: Hippocratea celastroides, Hippocrataceae, roots, Diels-Alder adducts, diterpenoids, triterpenoids, x-ray diffraction, insect antifeedants, stored grain insects, Sitophyllus zeamays, insecticidal plants, Diels-Alderase.

Through the careful design of a tecton and the selection of an adequate synthon we were able to design and build a non-centrosymmetric crystal through π–π stacking interactions.

1-phenyl-1,2-propanedione bis{N(4)-methyl- and {N(4)-ethylthiosemicarbazone}, H2Pm4M and H2Pm4E, respectively, have been prepared, studied spectroscopically (1H NMR, ultraviolet and infrared) and their crystal structures solved. Intermoiety hydrogen bonding does not occur in H2Pm4M and H2Pm4E, in contrast to the analogous bis{N(4)-thiosemicarbazones} prepared from 1-phenylglyoxal. The two thiosemicarbazone moieties are on the opposite side of the carbon–carbon backbone, but the N(4)Hs intramolecularly hydrogen bond to the imine nitrogen for each moiety.

Reduction of 2-cyanopyridine by sodium in dry methanol in the presence of N(4)-methylthiosemicarbazide produces 2-pyridineformamide N(4)-methylthiosemicarbazone, HAm4M. Complexes with iron(III), cobalt(II,III) and nickel(II) have been prepared and characterized by molar conductivities, magnetic susceptibilities and spectroscopic techniques. In addition, the crystal structures of HAm4M, [Ni(Am4M)(OAc)], [Fe(Am4M)2]ClO4 and [Co(Am4M)2]ClO4 have been solved. Coordination is via the pyridyl nitrogen, imine nitrogen and thione or thiolato sulfur when coordinating as the neutral and anionic ligand, respectively.

The physical and spectroscopic data of (R)-2-[N-(1-phenylethyl)amino]-1-cyclopentenedithiocarboxylic acid are reviewed and the synthesis of (R)-di-[2-(N-(1-phenylethyl)amino]-1-cyclopentenedithiocarboxylic acid disulfide is described. The product resulting from the conjugate addition of the dithioacid to 2(5H)-furanone is also characterised.

N-(2-pyridyl)-N′- o -tolylthiourea, monoclinic, P2 1 /c, a =5.127(1), b =19.854(2), c=12.077(2) A , β =94.96(1)°, V=1224.7(2) A 3 , Z =4, μ=2.177 mm −1 , N-(2-pyridyl)-N′-m-tolylthiourea, triclinic, P−1, a =9.811(2), b =9.887(4), c=13.595(3) A , α =74.91(3), β =83.58(2), γ =76.27(2)°, V=1235.(7) A , Z =4, m=2.469 mm −1 and N-(2-pyridyl)-N′-p-tolylthiourea, triclinic,P−1, a =9.935(2), b =11.488(2), c=12.569(2) A , α =63.91(2), β =88.60(2), γ =75.04(2)°, V=1238.1(2) A 3 , Z =4, μ=2.154 mm −1 all have an intramolecular hydrogen bond between N′H and the pyridyl nitrogen, as well as intermolecular hydrogen bonding between NH and a thione sulfur of a second molecule to form centrosymmetric dimers. Solution 1 H NMR studies (CDCI 3 ) show the N′H resonance considerably downfield for each thiourea and its position, as well as that of NH, are affected by substituents on the phenyl ring.

A 1:2:2 complex of diaza crown ether 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane, anthraflavic acid (2,6-dihydroxyanthraquinone) and water has been synthesized. The crystal is triclinic, P1, with a = 7.705(2), b = 10.871(2), c = 11.540(2) A, α = 100.40(2), β = 91.38(2), γ = 98.01(2)°, Z = 1, and Dcalc = 1.375 mg m−3. The main feature of the crystal structure is the formation of a supramolecular sheet by hydrogen bonding of the anthraflavic monoanions, not only head-to-tail through the hydroxyl oxygens, but sideways through the quinone oxygens. This complex represents an intermediate case between total transfer of protons of a hydroxy-guest to crown N-atoms, and no transfer.

The rhodium(II)-catalysed reaction of the diazoketone derived from 5-(4-methoxybenzoyl)-2,3-dihydropyrrolizin-1-carboxylic acid (anirolac) did not give the expected intramolecular cyclisation product but afforded the 2,3-dihydropyrrolizin-1-one only an elimination product. X-ray studies confirmed the structure.

There are two independent mol­ecules in the asymmetric unit of the title compound, C21H18N6S. The mol­ecules are linked by C—H⋯S and C—H⋯N inter­molecular and π–π stacking inter­actions.