Volume 39, Issue 9

TlI 3 (CH 3 C 5 H 4 NO) 2 is obtained in acetonitrile by the reaction of TlI with iodine and 3-methyl- pyridine-N-oxide. It crystallizes monoclinic in the centrosymmetric space group C2/c with lattice parameters at 190 K, a = 1756.5(8), b = 780.7(5), c = 1397.1(4) pm, β = 110.26(3)° and Z = 4. The structure consists of monomeric complexes, in which the Tl atom shows a fivefold coordina­tion in form of a slightly distorted trigonal bipyramid, the I atoms being located in the equatorial plane. The symmetry of the complex is C 2 whereby the Tl atom and one of the I atoms occupy the twofold axis.

Crystals of the adduct Li 3 [Fe(CN) 6 ] · 2C 6 H 12 N 4 -5H 2 O are orthorhombic, space group I2mm, Z = 2, a = 909.4(5), b = 1046.1(5), c = 1455.8(5) pm. The structure may be regarded as a packing of Fe(CN) 6 octahedra and hexamethylenetetramine molecules. The lithium ions are coordinated to nitrogen atoms of both groups and to water molecules. Mossbauer spectra have been recorded for the temperature range between 290 K and 77 K. At all temperatures the spectra show two doublets with nearly identical isomer shifts but different quadrupole splittings, thus indicating the presence of two kinds of hexacyanoferrate(III) ions with slightly different distortions of the ligand spheres around the Fe atoms. The effect is discussed on the assumption of a statistical distribution of one of the lithium ions.

Triethanolammonium tetrachloroantimonate was synthesized and investigated by X-ray diffrac­tion analysis. The structure consists of SbCl 3 molecules, chloride ions and triethanolammonium cations. The SbCl 3 molecules and the cations form adducts by a bridging O-atom at 274.3 pm. The Sb-Cl distances within the SbCl 3 molecule are 239.2, 240.3 and 245.3 pm, whereas the distances from the Sb atom th the Cl - ion are 290.2 and 332.1 pm.

The syntheses of two binuclear complexes of molybdenum(III) is reported. The oxidation of LMo(CO) 3 (L = 1,4,7-triazacyclononane, C 6 Hi 5 N 3 ) with bromine in chloroform (0.75% ethanol) yields the monomeric complex [Mo v LOBr 2 ](Br 3 ) (μ eff (298 K) = 1.61 μ B ). Reduction of this species in aqueous solution with Zn under an argon atmosphere at 25 °C affords - upon addition of NaBr - green crystals of [Mo 2 L 2 (μ-OH)(μ-Br)Br 2 ]Br 2 · 4H 2 O. The reduction at elevated temperatures yields green crystals of [Mo 2 L 2 (μ-OH) 2 Br 2 ]Br 2 ·2 H 2 O. Both complexes exhibit antiferromagnetic behaviour. The crystal structure of [Mo 2 L 2 (μ-OH)(μ-Br)Br 2 ]Br 2 · 4 H 2 O con­sists of dinuclcar cations, bromide ions and water of crystallization. It crystallizes in the triclinic space group P1 with cell constants a = 821.3(3). b = 837.7(2), c = 1008.1(3) pm, α = 103.63(2)°, β = 98.92(2)°, γ = 79.54(2)° and Z = 1. The two Mo(III)-centers are in a distorted octahedral environment of the tridentate amine, a terminal bromo-ligand and one hydroxo- and one bromide bridging ligand (edge sharing). The short Mo-Mo distance of 255.8(3) pm indicates strong metal- metal bonding.

Reaction of hexamethyldisilazane with (2-hydroxyphenyl)diphenylphosphane 1 affords the trimethylsilyl derivative 2-(Me 3 SiO)-C 6 H 4 -PPh 2 (2). The Si-O-bond is cleaved by various phos­phorus halides, e.g. [Bu n 3 PF] + Br - , PhPCl 2 , PCl 3 , Ph 2 PF 3 and PhPF 4 with formation of the cor­responding P-O-derivatives and trimethylfluoro- or trimethylchlorosilane, respectively. The 31 P{ 1 H} NMR spectra of the products are discussed. [2-(Bu n 3 PO)-C 6 H 4 -PPh 2 ] + Br - (7) on reac­tion with nickel(II) bromide forms a paramagnetic complex of composition NiBr 2 L 2 (L = 7). A distorted tetrahedral coordination geometry at Ni may be derived from its magnetic moment, electronic spectra and conductivity data. The structure of the hydrobromide of 1 shows strong hydrogen bonding between the OH- and PH-group of the cation and the bromide anion (P-H 1,42 Å, H···Br 2,41 Å, angle P-H···Br 150°; O-H 1,00 Å, H···Br 2,09 Å, angle O-H···Br 176°).

The reaction of [IrCl 6 ] 2- with BrF 3 generates the mixed complexes [IrF n Cl 6-n ] 2 -, n = 1-5, of which the species with n = 2, 3, 4 are ds-configurated. Due to the stronger trans-effect of Cl as compared to F on treatment of [IrF 5 Cl] 2 - and cis-[IrF 4 Cl 2 ] 2- with SOCl 2 the trans-isomers are formed stereospecifically. The pure fluoro-chloro-iridates(IV) are separated by ion exchange chromatography on diethylaminoethyl-cellulose. The vibrational spectra of the mixed ligand complexes are completely assigned according to point groups D 4h , C 4v , C 3v , and C 2v . The IrCl stretching vibration of [IrF 5 Cl] 2- is split by the isotopes 35 C1 and 37 Cl, showing two well resolved sharp Raman lines at 361 and 355 cm -1 .

Iron(III)oxide chloride is capable of intercalating ammonia and amines into its layer lattice. Long chain molecules form bilayers with extended chains almost perpendicular to the host lattice layers at room temperature (intercalate composition): FeOCl · (0.54 ±0.03) n -C x H 2x+1 NH 2 with x ≥ 12) and tilted by 57° at about 100-110 °C (intercalate composition: FeOCl · (0.45 ±0.02) n -C x H 2x+1 NH 2 with ≥12). The temperature-dependent changes in basal spacings between 20 and 110 °C are complex. Above 120 °C the layers of the host lattice are altered irreversibly by substitution and HCl-release to FeOCl 1-y (-NHC x H 2x+1 ) y with y ≤ ca. 0.4.

The coordinatively unsaturated fragment [CpRe(CO) 2 ], prepared by photolytic CO elimination from cyclopentadienyl tricarbonylrhenium, CpRe(CO) 3 (1), reacts with either S 8 or COS to give rhenium-sulfur complexes such as CpRe(CO) 2 S 2 (2), Cp 2 Re 2 (CO) 4 (μ-S) (3), and Cp 2 Re 2 (CO) 2 (μ-S 2 )(μ-S 3 ) (4). The X-ray crystal structures of the binuclear complexes 3 and 4 were determined: 3 contains a three-membered ring with a S atom bridging a formal Re-Re single bond (Re1 - Re2 2.946(1) Å. Re 1-S-Re2 76.4(1)°), while in 4 two sulfur-chain frag­ments, S 2 and S 3 , are used to bridge the two Re atoms in a seven-membered 1,4-dirhenia cycloheptasulfur ring.

UV photoelectron spectra of the title compounds are reported. Assignments are made with the help of He(I)/He(II) intensity differences, shift effects upon substitution and comparison with related molecules. Previously drawn conclusions about the electronic structure of similar com­plexes also hold for the compounds. It is indicated that the ionization energy for the symmetric metal-metal bond strongly depends on the overlap between transition and post-transition metals.

Matrix samples of F-CO-N 3 , and X-CO-NF 2 (X = H, NF 2 , CF 3 ) were photolyzed by mercury arc light and the new infrared bands at 2172, 861, 695, 646, 529 cm -1 assigned to the F-NCO molecule. 15 N isotopic substitution confirmed the assignment of the IR bands of the new compound.

The nucleophilic substitution reactions between dimethylgalliumchloride (1) and the silyl sul­fides (CH 3 ) 3 SiSR (R = CH 3 , C 2 H 5 , n-C 3 H 7, i-C 3 H 7 , Ph and CH 2 Ph) (2-7) in benzene result in the formation of the moisture-sensitive dimethyl(alkylthio)- and dimethyl(phenylthio)gallanes (CH 3 ) 2 GaSR (R = CH 3 , C 2 H 7 , n-C 3 H 7, i-C 3 H 7 , Ph and CH 2 Ph) (8-13). Compounds 8-11 are trimeric in benzene solutions, whereas compounds 12 and 13 appear to be monomeric. The synthesis of dimethylgalliumchloride starting from trimethylgallane or methylgalliumdichloride and galliumtrichloride is reported as well.

Tetrachloroantimony trimethylsilylcarbodiimide, Cl 4 SbNCNSiMe 3 , has been synthesized by the reaction of SbCl 5 with Me 3 SiNCNSiMe 3 in a 1:1 molar ratio. The pale yellow compound is dimeric in solution and in the solid state and has according to the vibrational spectra a centrosymmetric structure of C 2h symmetry. The X-ray structure determination shows the monoclinic space group P2 1 /c with two dimeric units per cell. The structure was refined to an R-value of 0,04.

The N -P-N-ligands RP(XC 5 H 4 N) 2 (1b′, c′, b″, c″) [X = O: R = t-Bu (b′), Me (c′); X = NH: R = t-Bu (b″), Me (c″)] are characterized by their different complex chemical behaviour towards group VI metal carbonyl derivatives. By reaction of 1b′, c′, b″, c″ with (CH 3 CN) 3 M(CO) 3 the complexes (OC) 3 M[RP(XC 5 H 4 N) 2 ] (2b′, c′, 3b″) and (OC) 4 W|[CH 3 P(NHC 5 H 4 N) 2 ] (3c″) [M = Mo (2).,W(3)] are formed in which the ligands are tridentate and bidentate, respectively. This difference can be explained with the existence of hydrogen bridge linkages between NH and pyridyl groups in 3c″. Homologation experiments of methanol with 1, CoOAc : and I 2 as an activator show high conversions (85%) with about 40% of ethanol selectivity. The lowest selectivities are found with 1c″.

Changes in X-nuclei screening and scalar spin-spin X-H(D) coupling constants induced by the H-D substitutions in isotopomers [XH 4-n D n ] (X = N, Al, Ga) have been determined by 14,1l5 N, 27 AI, 69,71 Ga NMR. Isotopic chemical shifts of nuclei 51 V, 53 Cr, 99 Tc induced by the 16 O- 18 O substitution have been measured for tetra-oxo complexes [VO 4 ] 3- , [CrO 4 ] 2- , and [TcO 4 ] - . The deuterium-induced secondary isotopic effect on the screening constant of the X nuclei and the scalar spin-spin X-H(D) coupling are correlated with the X-H bond length in [XHJ for the row X = N, C, B, Al, Ga, As the internuclear X-H distance increases, the isotopic shift of the X nuclei with respect to the signal from [XHJ rises linearly on H-D substitution from a negative value for [NH 4 ] + , CH 4 to a positive value (the downfield shift) for [GaH 4 ] - . When D is substituted for H in [XH 4 ] the X-H spin-spin coupling constant decreases for X = N, C, B, Al, Ga (the secondary isotopic effect). The magnitude and sign of the secondary isotopic effects on the screening constants of the X nuclei in [XH 4 ] and [XO 4 ] depend on the atomic number of the X element. With the increasing atomic number in the period the isotopic shift to high field rises in magnitude, while with the increasing atomic number in the group the isotopic upfield shift drops in the absolute value and can even change sign in the substitution of the ligand light isotope by a heavier isotope.

The oxidation of iron by iodine in acetonitrile and tetrahydrofuran solution leads to specific redox equilibria. In dependence of the molar ratios of Fe and I 2 the following compounds are isolated: Fe(CH 3 CN) 6 Fel 4 , Fe(CH 3 CN) 6 (I 3 ) 2 , Fe(C 4 H 8 O) 6 [FeI 3 (C 4 H 8 O)] 2 . When Et 4 NI is added to a tetrahydrofuran solution of FeI 2 and I 2 , Et 4 NFeI 4 can be obtained Evidence is presented for the stability of Et 4 NFeI 4 to autoreduction. A resonance Raman spectrum has been obtained for Et 4 NFeI 4 . Crystal data for the different compounds are reported.

The boranediylation of dihydroxy compounds and exchange reactions involving R-B-O groups of a number of their O-boranediyl derivatives with 18 O and 10 B labelled triethylboroxines has been investigated. It has been found that in simple 1,2-dihydroxy compounds only the RB group is substituted or exchanged. In hydroxy compounds such as ninhydrin 7 and octahydroxy- cyclobutane 6 both RB and RBO groups are involved. The mechanisms of these exchange reactions arc discussed.

We report the syntheses and IR spectra of phosphanciminato complexes of molybdenum: (Mo V Cl 4 (NPPh 3 )(PPh 3 )] (I) PPh 4 [MoIVCl 4 (NPPh 3 )(PPh 3 )] · 2CCl 4 (II) PPh 4 [MoVCl 5 (NPCl 3 )] (III) I is obtained from [MoNCl 4 ] 2 and triphenylphosphane, or from [MoCl 4 (NSCl)] 2 and triphenylphosphane: II was prepared by reacting MoNCl 4 with triphenylphosphane followed by treatment with tetraphenylphosphonium chloride; III can be generated from PPh 4 [MoNCl 4 ] with PCl 3 /PCl 5 . Complex I is paramagnetic (μeff, = 1.83 B.M., d 1 -configuration): II is diamagnetic (d 2 -system).

The chloroarsenates(III) N-Methylanilinium-tetrachloroarsenate(III) (1). tris-pyridinium- nonachloro-diarsenate(III) (2) and bis-pyridinium-μ-dichloro-μ-oxo-tetrachlorodiarsenate(111) (3) have been prepared, the latter by partial hydrolysis of 2. Their structures have been determined by X-ray structural analysis and shown to contain discrete As 2 Cl 8 2- (1), As 2 Cl 9 3- (2) and As 2 Cl 6 O 2- (3) anions. Pseudo-octahedral coordination is observed for the As-atoms in 1 and 3. The anion dimensions and the absence of chain building for anions 1 and 3 are in accordance with a markedly weaker acceptor strength of AsCl 3 in comparison to SbCl 3 .

N-methylanilinium-tetrabromoarsenate(III) (1). pyridinium-tetrabromoarsenate(III) (2), and tris-pyridinium-nonabromo-diarsenate(III) (3) habe been prepared and their structures deter­mined by X-ray structural analysis. 1 contains discrete As 2 Br 8 2- anions with C i symmetry, 2 infinite (AsBr 4 - ) n chains and 3 discrete As 2 Br 9 3- anions. Pseudo-octahedral coordination is ob­served for the As atoms in 1. The bridging As-Br bonds in As 2 Br 9 3- are markedly stronger than the analogous As-Cl bonds in the tris-pyridinium salt of As 2 Cl 9 3- .

Hydroxyl radicals (and H atoms) generated in the radiolysis of N 2 O-containing water add to ethylene forming β-hydroxyethyl radicals (and ethyl radicals). In the presence of oxygen these are converted into the corresponding peroxyl radicals which decay bimolecularly (2k = 2 x 10 8 M -1 s -1 ) as measured by pulse radiolysis. The major products (G values in brackets) are glycolaldehyde (3.3). formaldehyde (1.6), ethylene glycol (0.8), acetaldehyde (0.5). organic peroxidic material (0.5). and hydrogen peroxide (2.4) (dose rate 0.26 Gy s -1 , pH 5.6). A material balance has been obtained with respect to the primary water radicals (6.0) and oxygen uptake (4.8). The products and their yields can be accounted for if in the rate determining step atetroxide is formed which decomposes via three major pathways leading to: (i) H 2 O 2 and two molecules of glycolaldehyde (ca. 45%), (ii) O 2 , glycolaldehyde and ethylene glycol (ca. 30%). and (iii) O 2 . two molecules of formaldehyde and two CH 2 OH radicals (ca. 15%). A 1,2-H shift of intermediate oxyl radicals is unimportant in this system.

Alkylation of [Fe(CO) 2 (S 2 C 6 H 4 ) 2 ] 2- by Br(CH 2 ) n Br (n = 1,3-6) or CICH 2 COCH 2 Cl yields [Fe(CO) 2 (C 6 H 4 S 2 -(CH 2 ) n -S 2 C 6 H 4 )] and [Fe(CO) 2 (C 6 H 4 S 2 -CH 2 COCH 2 -S 2 C 6 H 4 )]. respectively. With long-chain dibromoalkanes (n = 7,8,12) the oligonuclear complexes [Fe(CO) 2 (C 6 H 4 S 2 - (CH 2 ) n - S 2 C 6 H 4 )] x also form; in these cases the mononuclear complexes can be obtained by dilution methods. Growing length of the bridge between the thioether donor atoms favours the loss of CO and formation of [Fe(CO)(C 6 H 4 S 2 -(CH 2 ) 3 -S 2 C 6 Η 4 )] 2 and [Fe(C 6 H 4 S 2 - (CH 2 ) n -S 2 C 6 H 4 )] x (n = 1,4-8,12). respectively; substitution rate of CO by PMe 3 is increased as well. Hydrolysis of the Fe(CO) 2 complexes by HCl gives the free tetradentate thioetherthiol ligands HSC 6 H 4 S - (CH 2 ) n - S 2 C 6 H 4 SH.

Dimerizations and reactions with water of pyrimidine bases are the primary steps held respon­sible for the deformation of DNA at short wavelengths in vitro and in vivo experiments. However the influence of oxygen in combination with water on the UV deformation at wavelengths rep­resentative for troposphere is evident from the observed data and both together are needed to change the DNA structure. The only plausible explanation for the effect of oxygen is the forma­tion of reactive oxygen species during the UV irradiation of DNA. In the present work the deformation of DNA by different oxygen species like singlet oxygen ( 1 O 2 ), superoxideanion (O 2 - ), hydroxyradical ( · OH), ozone (O 3 ) and hydrogenperoxide (H 2 O 2 ) is excluded with the help of chemical-trapping experiments. The photo-induced transformation proceeds via excited states of DNA. which react with groundstate oxygen to afford peroxide.

From the liverwort Scapania bolanderi eight kinds of diterpenoids have been isolated together with two kinds of sesquiterpenoids, and seven of them have been identified as the verruconsane and neoverrucosane diterpenoids with 3,6,6,5-tetracyclic carbon framework.

Photodimerization of 3,5-diaryl-2-cyclohexenones (1) in benzene solution gave the dimers 3. “Head-to-tail” structures are assigned for 3 on the basis of spectroscopic studies and reasoning from molecular models. Photolysis of the 3-styryl derivatives (5) afforded bicyclo[4,2,0]octan-1,5-dienes (8).

A new indolenine alkaloid, “Lahoricine” has been isolated from the leaves of Ervatamia coronaria to which structure 1 has been assigned.

The isolation and structure of a new pseudoindoxyl alkaloid from Catharanthus roseus leaves is described.