Volume 59, Issue 7

In summary, the thermal behaviour of the ternary phases in the pseudo-binary systems Bi 2 Ch 3 /BiX 3 are described. The thermodynamic data of these phases have been analysed and the appropriate values are given here. The phase diagrams and barograms have been calculated with these data and they are compared with the diagrams that have been obtained experimentally. The crystal structures of the various phases are briefly described.

In order to study hydrogen bonding networks and packing arrangements, preparations and lowtemperature X-ray structures are reported for three ionic solids of general formula BH + (MeSO 2 ) 2 N − , where BH + is 2,6-diamino-4-phenyl-1,3,5-triazin-1-ium (compound 1, tetragonal, space group P4̅2 1 c, Z = 8), 2,4,6-triamino-1,3,5-triazinium or melaminium (2, monoclinic, P2 1 /c, Z = 4), and 2,4-diamino-6-methyl-1,3,5-triazin-1-ium (3, triclinic, P1̅, Z = 2). The asymmetric units consist of cation-anion pairs that display in 1 a [DDD:AAA] three-point hydrogen bond pattern formed by two lateral N-H···O bonds and a central N + -H···N interaction, in 2 a related pattern, in which the substantial lateral offset of the ions causes the two-centre H bonds to split up into three-centre bonds, and in 3 a [DD:AA] two-point pattern formed by an N-H···N and an N + -H···O interaction. All NH donors that are not involved in the ion pairs use sulfonyl oxygen atoms and/or non-protonated nitrogen ring-atoms as acceptors to form, in 1 and 3, discrete cation-anion strands, and in 2 similar strands associated into a three-dimensional network via one independent N-H···O bond. The packing topologies of the strands may be viewed as supramolecular analogues to molecular arrangements occurring in crystalline polyaromatic hydrocarbons, viz. the sandwich-herringbone pattern in 1 (sustained by π···π stacking of the triazine rings within the sandwiches and a phenyl-phenyl C-H···π interaction between orthogonal sandwiches), the flattened or γ -type herringbone pattern in 2 (sustained by the unique N-H···O interaction of orthogonal strands), and the pseudo-graphitic β -pattern in 3. In each packing, weak C-H···A hydrogen bonds (A = O, N) originate from the activated methyl groups of the anions and act as structure-supporting links between the cation-anion strands.

A new trinuclear complex [Co(NiL) 2 (H 2 O) 2 ](ClO 4 ) 2 was synthesized by using a macrocyclic complex ligand [NiL], where L is the dianion of diethyl-5,6,7,8,16,17-hexahydro-6,7-dioxo-16Hdibenzo[ e,n] [1,4,8,12]tetraazacyclopentadecine-13,19-dicarboxylate. X-ray analysis revealed that the two Ni(II) ions have the same distorted N4 square planar coordination geometries. The Co(II) ion resides in a distorted octahedral O6 coordination environment. In the crystal, π···π interaction between a phenyl ring and three non-aromatic π-systems involving Ni and N atoms was observed together with C-H···O and O-H···O hydrogen bonds. These non-covalent interactions link the dications and the perchlorate anions to form a 3D supramolecular network.

The preparation of room-temperature ionic liquids 1-butyl-3-methylimidazolium chloride, hexafluorophosphate, and dicyanamide by microwave-assisted reaction in non-solvent and solvent conditions has been studied in this contribution. A special emphasis is put on the effect of the reaction temperature on the purity of ionic liquids that was monitored by electrospray ionisation mass spectrometry and 1 H NMR. The X-ray structure of 1-butyl-3-methylimidazolium chloride is presented.

The title compounds were synthesized at a temperature of 775 K via reaction of Fe 2 O 3 with elemental cesium and rubidium alone or in combination with their hyperoxides AO 2 where required by stoichiometry. The structures of the dark-red crystals have been determined by single crystal x-ray diffraction (Cs[FeO 2 ]: cubic, space group Fd3m, a = 839.2(2) pm, Z = 8, R1 = 0.0547 and A5[Fe 3 O 6 ] (A = Cs: orthorhombic, space group P2 1 2 1 2 1 , a = 861.8(2), b = 870.7(2), c = 1658.7(3) pm, Z = 4, R1 = 0.0617 and A = Rb: tetragonal, space group I4̅2d, a = 862.01(8), c= 1504.7(2) pm, Z =4, R1= 0.0334). These three compounds contain three-dimensional networks [FeO 2 ], in the case of the ideal stuffed cristobalite composed of corner-sharing tetrahedra [FeO 4/2 ], in the case of the new mixed valence compounds A 5 [Fe 3 O 6 ] formed by corner-sharing of tetrahedra [Fe III O 4/2 ] and triangles [Fe II OO 2/2 ] in a 1:2 ratio. The crystal structure of the cation rich compound Cs 8 [Fe 2 O 7 ] (monoclinic, space group P2 1 /c, a = 722.32(12), b = 1789.0(3), c = 733.88(12) pm, β =118.976(3)°, Z = 4, R1=0.0287) exhibits di-ferrate anions [Fe 2 O 7 ] 6− composed of two cornersharing [Fe III O 4 ] tetrahedra with a linear Fe-O-Fe bridge.

On heating bis(diiodoboryl)methane (1c) and 1,1-bis(diiodoboryl)alkanes 1i, l (alkane = propane, butane) under reduced pressure elimination of BI 3 takes place and the corresponding 1,3,5-triiodo- 1,3,5-triboracyclohexane derivatives 2c; 2i, i’; 2l, l’ are formed. Starting with bis(dichloroboryl)- and bis(dibromoboryl)methane (1a, 1b) only small amounts of the trimerization products (H 2 C-BCl) 3 (2a) and (H 2 C-BBr) 3 (2b) are detectable which can not be separated from 1a,b and by-products. Reaction of 1,3,5-trichloro-2,4,6-trimethyl-1,3,5-triboracyclohexane (2d) with BBr 3 provides the corresponding bromo derivative 2e in high yield. An attempt to react 2,4-bis(dichloroboryl)-3-chloro- 3-borapentane (4d) with 1,1-bis(trimethylstannyl)-2,2-diphenylethene does not lead to the expected trichloro-triboracyclohexane, but the divinylchloroborane ClB(CH=CPh 2 ) 2 6a, is formed. The compositions of the products follow from analytical data and X-ray structure analyses of 2i, 2c, 2e, and 6a.

Treatment of the monomeric organogallium subiodide R(I)Ga-Ga(I)R 1 [R = C(SiMe 3 ) 3 ] with the diironcarbonylate anion [Fe 2 (CO) 8 ] 2− yielded the red iron gallium compound Fe 2 (CO) 6 (μ-GaR) 3 2 in moderate yield. 2 may be described as an analogue of enneacarbonyldiiron Fe 2 (CO) 9 , the three bridging carbonyl groups of which are replaced by GaR ligands.

All three structures of the form bis(thione)gold(I) camphor-10-sulfonate [thione = imidazolidine-2-thione, 1; 1-methyl-imidazolidine-2-thione, 2; thiazolidine-2-thione, 3] crystallize in chiral space groups with Z′ = 2; local inversion symmetry of the cationic assemblies (less pronounced for 3) provides some rationalisation for this. The basic structural units are accounted for in terms of classical hydrogen bonds, leading to rings involving ion pairs for 1 and 2, but to infinite chains of anions and cations for 3. Neighbouring ion pairs in 1 are joined by further classical hydrogen bonds, in 2 via interactions between parallel S-Au-S axes. Other interactions include Au···N for 1, Au···S and Au···O for 3, and weak hydrogen bonds C-H···O and C-H···S, especially between adjacent chains in 3. Each structure is divided into hydrophobic and hydrophilic regions.

An improved synthesis of 6-O-benzyl guanine which is an important inhibitor of O 6 -alkyl-guanine DNA alkyltransferase (AGT) is described. In addition the conjugation of this guanine derivative was achieved with a functionalised hydrophilic linker which is of interest for immobilisation of this inhibitor and its conjugation with targeting components.

A new biologically active cyclic peptide, Pseudostellarin G was synthesized and the structure was established on the basis of analytical, IR, NMR and mass spectral data. The newly synthesized compound was screened for its antimicrobial and pharmacological activities.

Two new triterpene saponins (1 and 2), named bidenosides A and B, were isolated from the roots of Knautia integrifolia var. bidens. The structures were identified as 3-O-α-L-rhamnopyranosyl-28- O-[β -D-allopyranosyl-(1→6)-β -D-glucopyranosyl]-pomolic acid, and 3-O-α-L-rhamnopyranosyl- 28-O-[β -D-allopyranosyl-(1→6)-β -D-glucopyranosyl]-oleanolic acid on the basis of spectroscopic evidence.

The chemical composition of a diethyl ether extract of the Scottish liverwort Pedinophyllum interruptum has been examined. Two new prenylated benzoic acid derivatives, methyl 2,6- dihydroxy-4-methoxy-3-(3’-methyl-2’-butenyl)benzoate and methyl 2,4,6-trihydroxy-3-(3’-methyl- 2’-butenyl)benzoate, two new chromenes, methyl 5,7-dihydroxy-2,2-dimethyl-2H-chromene-6- carboxylate and methyl 7-hydroxy-5-methoxy-2,2-dimethyl-2H-chromene-8-carboxylate, and the two known chromenes methyl 8-hydroxy-2,2-dimethyl-2H-chromene-6-carboxylate and methyl 8- methoxy-2,2-dimethyl-2H-chromene-6-carboxylate were isolated. Methyl 2,4,6-trihydroxy-3-(3’- methyl-2’-butenyl)benzoate was unstable in air and was quickly converted into methyl 2,4,6- trihydroxy-3-(2’-hydroperoxy-3’-methyl-3’-butenyl)benzoate. All structures were elucidated by means of NMR spectroscopic techniques and mass spectrometry.

The pine weevil Hylobius abietis (L.) (Coleoptera: Curculionidae) feeds on the bark of coniferous seedlings and is the economically most important forestry restocking pest in large parts of Europe. Substances with an antifeedant effect may offer an environmentally friendly alternative to insecticides for the protection of planted seedlings. Bioassays were performed on commercial and synthetic methyl hydroxy-methoxybenzoates in order to determine their possible antifeedant activity. Two methyl hydroxy-methoxybenzoates were synthesized by esterification and mono-O-methylation of two dihydroxybenzoic acids. A regioselective protection-deprotection strategy was used in the synthetic pathway of the other non-commercial esters, esterification and selective pivaloylation of the less-hindered hydroxyl group of other commercial dihydroxybenzoic acids gave diester intermediates, which then were O-methylated before methanolysis of the pivaloyl group which yielded the desired non-commercial methyl hydroxy-methoxybenzoates. The five synthesized methyl hydroxy-methoxybenzoic esters were complemented with commercial samples of the five other isomers of methyl hydroxy-methoxybenzoate and spectrometric data were collected for the complete set of isomers. All ten isomers were tested for their antifeedant effect on the pine weevil. The effect varied considerably among the hydroxy-methoxybenzoic esters. Methyl 2-hydroxy-3-methoxybenzoate showed the highest effect and may thus be a candidate for practical use in pine weevil pest management.

The complexes fac-[Re(CO) 3 Br{Ph 2 P(S)(CH 2 ) n P(S)Ph 2 }] [1a, n = 1; 2a, n = 2; 3a, n = 3] and [Re 2 (CO) 8 Br 2 {μ- Ph 2 P(S)(CH 2 ) n P(S)Ph 2 }] [1b, n = 1; 2b, n = 2; 3b, n = 3] have been prepared by the photochemical reaction of Re(CO) 5 Br with Ph 2 P(S)(CH 2 ) n P(S)Ph 2 . The products have been characterized by elemental analysis, mass spectroscopy, FT-IR and 31 P-[ 1 H]-NMR spectrometry. The results suggest cis-chelate bidentate coordination of the ligand in fac-1a - 3a and cis-bridging bidentate coordination of the ligand between two metals in 1b - 3b.

The synthesis of some new electron π-donors carrying four or two methoxy groups is described. The precursor 5,6-dimethoxy-5,6-dihydro[1,3]dithiolo[4,5-b] [1,4]dithiin- 2-thione was synthesized and by coupling reactions the symmetrical 5,6,5’,6’-tetramethoxy-5,6,5’,6’-tetrahydro- [2,2’]bi[[1,3]dithiolo[4,5-b][1,4]dithiinylidene] and unsymmetrical 5,6-dimethoxy-5,6,5’,6’-tetrahydro-[2,2’]bi[[1,3]- dithiolo[4,5-[1,4]dithiinylidene], 2-(5,6-dimethoxy-5,6-dihydro-[ 1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene)-5,6-dihydro-[ 1,3]dithiolo[4,5-b][1,4]-dioxine and (5,6-dimethoxy- 5,6-dihydro-[1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene)-6,7- dihydro-5H-[1,3]dithiolo[4,5-b][1,4]dithiepine donors were prepared. They have been characterized spectroscopically and their redox potentials determined using cyclic voltammetry.