Volume 47, Issue 7

We have observed that the superoxide anion reacts with VO(salen), but not with VO(saldpt), where H 2 (salen) and H 2 (saldpt) are Schiff base ligands derived from salicylaldehyde and ethylenediamine or dipropylenetriamine, respectively. Based on the electrochemical, ESR, and UV spectroscopic studies of the reaction mixture, it was concluded that the superoxide anion reacts with VO(salen) to oxidize V(IV) to V(V) through the formation of a vanadium(V)-peroxide adduct with side-on configuration. The SOD-like function of VO(salen) was elucidated in terms of the above assumption.

Ligand fluctuations in complexes [Co(Kr5)]X 2 (Kr 5 = 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane) with X = ClO 4 - , CF 3 SO 3 - can be detected by NMR spectroscopy above room temperature in inert solvents such as nitromethane. This unusually slow ligand movement is due to the strong coordination of the quinolyl end groups to the Co(II) ion as demonstrated through measurements with oligo-ethylene-glycols. In contrast to the 13 C spectra, the 1 H 2 D EXCSY NMR spectra reveal cross peaks which are due to a magnetisation exchange between the chemically non-equivalent protons in the -CH 2 - groups of the podand. This process is associated with a movement of the chain segments towards each other.

[Co 2 (CO) 6 (μ-S 2 )] 2+ (AsF 6 -) 2 · 1/2SO 2 is formed in the reaction of S 8 2+ (AsF 6 -) 2 with Co 2 (CO) 8 in SO 2 at R.T.. The complex crystallizes in the orthorhombic space group Pbcn (No. 60) with a = 1508.0(9), b = 1642.7(8), c = 871.3(6) pm, V = 2158(2)•10 6 pm 3 , Z = 4. In the tetrahedral Co 2 S 2 unit a short S–S distance (198 pm) is observed.

The halophenylantimonates(III) [Ph 4 P][Ph 2 SbCl 2 ] (1), [Ph 4 P][Ph 2 SbBr 2 ] (2), [Me 3 NH] 3 [Ph 2 Sb 2 Cl 7 ] (3) and [Me 3 NH] 3 [Ph 2 Sb 2 Br 7 ] (4) have been prepared and their structures established by single crystal X-ray diffraction. The anions [Ph 2 SbCl 2 ] - and [Ph 2 SbBr 2 ] - display w-trigonal bipyramidal geometries with axial halogen atoms. Sb-Cl [2.618(4), 2.601(4)Å] and Sb-Br distances [2.779(3), 2.794(2)A] are very similar to one another in the individual anions of 1 and 2. The anions [Ph 2 Sb 2 Cl 7 ] 3- and [Ph 2 Sb 2 Br 7 ] 3- both contain two square pyramidal coordination polyhedra which are vertex-linked to one another via Sb-X-Sb (X=Cl, Br) angles of respectively 152.9(1) and 152.3(1)°; the latter anion displays crystallographic C 2 -symmetry. trans-Sited Sb-Cl or Sb-Br bond distances in 3 and 4 are structurally correlated to one another.

Three new ternary compounds MnCuP, MnCuP 0.5 As 0.5 and MnCuAs have been prepared and characterized by X-Ray, DTA and magnetic measurements. They crystallize orthorhombically in the space group P nma (No. 62). The structures were calculated from single crystal data. The melting points were determined by DTA measurements (MnCuP: 1090°C; MnCuP 0.5 As 0.5 : 1000 °C; MnCuAs: 950 °C). MnCuAs appears to show an antiferromagnetic ordering up to 295 K.

The use of mass spectrometry for the analysis of transition metal complexes is demonstrated by combined high resolution Plasma Desorption Mass Spectrometry (PDMS) and Secondary Ion Mass Spectrometry (SIMS) investigations of the neutral nickel thiolate complexes [Ni 4 (SC 3 H 7 )8] (1), [Ni 4 (SC 6 H 11 )8] (2), [Ni 8 (SCH 2 COOEt) 16 ] (3) and [Ni 6 (SC 3 H 7 ) 12 ] (4). The positive spectra are dominated by three kinds of SI-species: (a) molecular ions, (b) fragment ions and (c) molecular ions with one or more substrate atoms attached. The negative spectra show mainly nickel sulfur cluster ions of the composition (Ni x S y ) - . In contrast to many Fast Atom Bombardment (FAB) spectra of neutral metal complexes, SIMS and PDMS spectra provide molecular weight as well as fragment ion information. Both techniques are most powerful tools for the investigation of coordination compounds because the samples are easy to prepare and the spectra are independent of matrix conditions. Additionally crystallographic studies have been carried out for 4. The hexanuclear complex 4 with square planar Ni-S coordination sites crystallizes in the trigonal space group R 3̅ with Z = 3 and α = 18.537(5), c = 13.966(3) Å.

Transparent single crystals of Na 4 Ga 2 S 5 were obtained from a melt of Na 2 S, Ga and S. Na 4 Ga 2 S 5 is monoclinic, space group P2 1 /c with a = 7.967(1), b = 6.133(2), c = 19.852(9) Å, β = 91.61(2)°, Ζ = 4. Its crystal structure was refined to a conventional R of 0.033 for 1150 observed reflections. The structure of Na 4 Ga 2 S 5 is of a new type. It is characterized by infinite ribbon like thiogallate anions, -, which are built up by GaS 4 -tetrahedra (mean Ga-S bond length 2.28 A) sharing apices and edges. The four crystallographically independent alkali cations are coordinated to six sulphur atoms in distorted octahedral configurations.

The complexes [1,2-diamino-l-(p-hydroxy)benzyl-1-(methyl, ethyl, and phenyl)]ethane-(dichloro)platinum(II) were synthesized and characterized. The benzylic p-hydroxy group of the 1,2-diaminoethane ligand leads to good water-solubility of the complexes. The ligands were synthesized in a Strecker-type reaction, starting from the corresponding p-methoxybenzylketones. The amino nitriles were reduced to the diamines. Finally, the p-methoxy groups were converted into hydroxy groups by ether cleavage. For the preparation of the complexes, K 2 PtCl 4 was added to the ligands. The antitumor activity of the platinum(II) compounds was tested towards the human mammary carcinoma cell line MDA-MB 231. The antitumor effect depends on the substituents and increases in the series phenyl, methyl, and ethyl. As a maximum, a growth inhibition value of 77% was obtained.

The main product from the reaction between bis(dimethylamino)fluoromethylidene-phosphorane (1) and n-butyllithium in the presence of tetramethylethylenediamine is n-butyl-dimethylamino-methyl-{[tris(dimethylamino)phosphoranylidene]methylene}-phosphorane (7). As a by-product from the reaction between methyl-bis(dimethylamino)difluorophosphorane and n-butyllithium bis(dimethylamino)-methyl-{[n-butyl-bis(dimethylamino)phosphoranylidene]methylene}-phosphorane (9) was isolated in small yield. The new carbodiphosphoranes 7 and 9 are characterized by their 1 H, 13 C, and 31 P NMR and mass spectra.

Ester cleavage of aspartame (L-α-aspartyl-L-phenylalanine methylester) (1), by equimolar quantities of thallium ethoxide is accompanied by intramolecular cyclisation to give thallium 3-benzyl-6-(carboxylatomethyl)-2,5-dioxopiperazine (2). The solid state structure of the crystalline product was determined by single-crystal X-ray diffraction analysis. The cations were found to form four short and four elongated contacts to seven oxygen atoms and one nitrogen atom of a total of six neighbouring 3-benzyl-6-(carboxylatomethyl)-2,5-dioxopiperazine anions. There are inter-anionic hydrogen bonds only between the imino groups and the carbonyl oxygen atoms (O3, O4), featuring a pattern similar to that found for cytosine-guanosine contacts in DNA.

Thermal decomposition of N 2 H 6 [CrF 5 (H 2 O)] has been investigated by thermoanalytical, X-ray and IR spectroscopic methods. Under quasi-isobaric conditions the decomposition takes place in several steps. The intermediate N 2 H 6 CrF 5 has been found which crystallizes monoclinically with α = 555.0 pm, b = 1084.6 pm, c = 777.0 pm, β = 91.76°. N 2 H 6 CrF 5 decomposes via an amorphous intermediate to give pure rhomboedrical CrF 3 as the final product. One of the intermediate has been identified as chromium fluoride ammoniate CrF 3 0.4 NH 3 . No hydrolysis reactions have been observed.

The title ligands bis[(2-pyridyl)methyl]amine (BPA) and bis[(2-benzimidazolyl)methyl]-methylamine (BBMA) were used to prepare complexes with zinc salts. 1:1 complexes of BPA with ZnCl 2 , ZnBr 2 , ZnI 2 , Zn(SCN) 2 , Zn(CH 3 COO) 2 , and Zn(NO 3 ) 2 as well as of BBMA with ZnCl 2 , ZnBr 2 , and Zn(NO 3 ) 2 were obtained. Spectroscopic evidence indicates that all these complexes are five-coordinate molecular LZnX 2 units. With Zn(ClO 4 ) 2 , BPA forms a 2:1 complex presumed to be an octahedral ionic L 2 ZnX 2 species. The crystal structures of BPA · ZnCl 2 and BBMA · ZnBr 2 reveal distorted square pyramidal resp. trigonal bipyramidal molecular geometries.

The reaction of thiobenzoylhydrazine with ReO 2 I(PPh 3 ) 2 and Re 2 O 3 (S 2 CNEt 2 ) 4 yields [Re(HNNC(S)Ph)(HNNHC(S)Ph) 2 ]I · OPPh 3 · MeOH (1), ReO(HNNC(S)PhXHNNHC(S)Ph) (2) and Re(HNNC(S)Ph) 2 (S 2 CNEt2) (3). Re(NNC(S)OMe)(S 2 CNEt2) 2 (4) is obtained from O-methylthiocarbazate and Re 2 O 3 (S 2 CNEt 2 ) 4 · ReCl 2 (PPh 3 ) 2 (NNC(O)Ph) reacts with functionalized hydrazines H 2 NNHR (R = C(S)Ph, C(S)OMe, C(O)SMe, C(S)SMe) to the diazenidohydrazino complexes ReCl 2 (PPh 3 ) 2 (NNC(O)Ph)(H 2 NNHR) (5-8). The structures of 1, 2, 5 and 6 have been determined. 1: monoclinic, space group Cc, a = 1892.1(2), b = 1227.3(1), c = 1858.4(2) pm, β = 98.34(1)°, Ζ = 4, 4544 reflections, R = 0.034; 2: monoclinic, space group P2 1 , a = 938.6(2), b = 637.0(1), c = 1356.0(3) pm, β = 98.96(3)°, Ζ = 2, 1905 reflections, R = 0.026; 5: triclinic, space group P1̄, a = 1236.4(2), b = 1414.8(2), c = 1780.8(3) pm, α = 111.02(2)°, β = 98.19(2)°, γ = 108.29(1)°, Ζ = 2, 4576 reflections, R = 0.067; 6: triclinic, space group P1̄̄, a = 1185.9(2), b = 1195.8(2), c = 1625.4(3) pm, a = 96.36(3)°, β = 99.54(3)°, γ = 103.93(3)°, Ζ = 2, 8006 reflections, R = 0.032. 1 and 2 contain N,S-chelating HNNR and HNNHR ligands. The ligand structures can be considered as intermediate between hydrazido(2—) or (1—) and diazene or protonated diazene type structures. In 5-8 the hydrazine derived ligands are monodentate N-coordinated.

[{Cp(CO) 3 Mo} 2 BiCl] 1 reacts with silylated chalcogens E(SiMe 3 ) 2 (E = S, Se) to give the compounds [{Cp(CO) 2 Mo} 2 EBiCl] (E = Se 2, S 3). The structures of 2 and 3 were determined by X-ray crystallography. In the solid state two [{Cp(CO) 2 Mo} 2 EBiCl] units are linked by two Bi—Cl—Bi bridges to form the dimer [{Cp(CO) 2 Mo} 2 EBiCl] 2 with a planar Bi 2 Cl 2 ring. The [{Cp(CO) 2 Mo} 2 EBiCl] units contain distorted Mo 2 BiE tetrahedra.

C-Borylmethyleneboranes with one or two O-Aryl substituents in the boryl group, 3 a and 4b, are obtained by cleavage of B–C single bonds in the presence of a B–C double bond. The duryl(methyl)borylmethyleneborane 7 is formed by thermal rearrangement of the vinylborane 5a. 4b has an almost normal B–C– B angle (118.3(7)°) and the most strongly deshielded dicoordinated boron atom (δ11B = 80) observed so far for methyleneboranes. This indicates weak C–B hyperconjugation in 4b. The distorted B–C– B angles in 3a (108.8(5)°) and 7 (98.1(5)°) and the shielded dicoordinated boron atom of 7 (δ 11 B = 63) in spite of its positivation by π-π delocalization demonstrate an increase of C–B hyperconjugation upon decrease of electronegativity of substituents in the boryl group.

Gd 2 Cl 3 is electrocrystallized from molten GdCl 3 at 900 K with a current efficiency of 70% referring to the reaction 2GdCl 3 +3e⁻=Gd 2 Cl 3 +3Cl - . The reaction is used to determine cocrystallization coefficients for trivalent rare earths and actinoids (Y, Nd, Cm, Pu), divalent lanthanoids (Eu, Yb), and Sr. The oxidation potential for the above reaction is determined as 2.65 ≤ E° ≤ 2.68 V.

Bis(isopropylcyclopentadienyl)zirconiumdichloride (1) was synthesized by the reaction of isopropylcyclopentadienyl lithium with 1/2 molar equivalent of zirconiumtetrachloride and then crystallized from methylenechloride. Complex 1 crystallizes in space group C2/c with cell parameters a = 24.492(3)A, b = 13.525(1)Å, c = 22.894(3)Å, β = 117.90(1)°, Z = 16, R = 0.046, R w = 0.057. There are three independent molecular entities of 1 in the asymmetric unit. These represent torsional isomers differing in the relative positions of the isopropyl substituents at the Cp-rings. The three torsional isomers may be described as anti-, syn-, and gauchelike metallocene rotamers.

Grignard reagents react with spirodiisophora-3′,6-dione exclusively at its 3′-keto-function, yielding 3′-eq-alkyl(or phenyl)-3′-ax-hydroxyspirodiisophor-6-ones. Successive dehydration and monobromination of the methyl homologue yields products, the structural details of which are settled by their 13 C NMR spectra.

Ethyl 4-bromo-2-(diphenylmethylene)-3-oxo-5,5-diphenyl-4-pentenoate (2) is formed on reaction of 2,4-bis-(diphenylmethylene)-1,3-cyclobutane dione (1) with bromine in the presence of ethanol. 2, C 32 H 25 BrO3, was characterized by X-ray structure analysis. Space group (orthorhombic) P Na 2 1 , Z = 8, a = 3459.3(2), b = 989.9(1), c = 1541.0(1) pm, R = 0.084.

The crystalline title pyrylium salt was obtained by SnCl 4 catalysed acylation of mesityl oxide with lauroyl chloride followed by treatment with perchloric acid and column chromatography. This new pyrylium salt was converted in high yields into the corresponding pyridine and N-substituted pyridinium salts (N-methyl, N-phenyl, N-(4-n-butylphenyl), and N-dodecyl) whose proton (300 MHz) and carbon-13 (75 MHz) NMR spectra are presented.

Reaction of 4-hydroxy-3-prenylquinolin-2(1 H)one (5 a) with iodine and silver acetate gave a iodopyranoquinoline (6 a), which was then converted into the alkaloids khaplofoline (1) and ribalinine (2). Reaction of 5a with iodine and mercuric oxide afforded a mixture of 6a and its angular isomer 7 a; the coversion of latter into flindersine (10) is described.

A convenient route to pyranoflavones (natural and synthetic) from acetyl hydroxy chromans via the corresponding dihydro analogues by the use of Claisen condensation in the key step is reported.

Tritium-labeling of the ingenol monoester 3-O-tetradecanoylingenol (3-TI), the prototype tumor promoter of the ingenane type diterpene esters, is described. The preparation starts with oxidation of 3-TI by manganese dioxide to yield 3-TI-20-aldehyde which is reduced by [ 3 H]-sodium borohydride in the presence of equimolar amounts of cerium trichloride hexahydrate to give [20- 3 H]-3-TI. The labeled promoter is obtained in 42% overall yield with a specific radioactivity of 15.8 Ci/mmol.

A facile synthesis of rhinacanthin-A is achieved by the side chain cyclization of lapachol with meta-chloroperbenzoic acid along with stenocarpoquinone-A, stenocarpoquinone-B and its isomer.

Enantiomers of N-trifluoroacetyl-amino acid methyl esters in CC1 4 solution, after addition of the chiral polysiloxane (L)-Chirasil-Val, display a chemical shift nonequivalence ΔΔδ in both 1 H NMR and 19 F NMR spectroscopy. The effects found for the leucine and valine derivatives can be correlated with the thermodynamic parameters of interaction in the undiluted system, as determined by gas chromatography. In CDC1 3 solution, no peak splitting was observed. The method is potentially useful for the determination of the enantiomeric purity of substrates of low volatility.

Novel antibacterially active oxapenem-carboxylic acids were prepared. Their increased stability depends on the 2-tert-butyl substituent and arises from its electron releasing inductive effect. The geometry and reactivity of oxapenems are discussed on the basis of two X-ray structure determinations and compared to those of related antibiotics.

(η 6 -1,4-Diphenyl-1,3-butadiene)tricarbonylchromium(0) has been synthesized in high yield by using an improved procedure, from tris(acetonitrile)chromium(0) and 1,4-diphenyl-1,3-butadiene. The IR and NMR spectroscopic data show that the organic ligand is bonded to the Cr(CO) 3 moiety through only one of the two phenyl rings.

[K(18-crown-6)][WF 5 (NCl)] has been prepared as yellow crystals by the reaction of KF with WCl 4 (NCl) in the presence of 18-crown-6 in acetonitrile solution. The compound was characterized by its IR spectrum and by an X-ray structure determination. Space group P2 1 /n, Z = 4, 3697 observed unique reflections, R = 0.034. Lattice dimensions at –65 °C: a = 1313.8(3), b = 851.2(1), c = 1842.7(4) pm, β = 95.304(1)°. The compound forms ion pairs, in which the pottassium ion is coordinated by the six oxygen atoms of the crown ether molecule and by two fluorine ligands of the [WF 5 (NCl)]- unit with K–F distances of 272.4(5) and 288.6(5) pm. The W=N–Cl group of the anion is nearly linear (bond angle 170.7(5)°) with bond lengths of WN = 172.4(7) and NCI = 162.7(7) pm.