Volume 36, Issue 8

The preparation of CH 3 SO 2 NBrCl and p-CH 3 C 6 H 4 NBrCl is described. These compounds react with (C 6 H 5 ) 4 Sn, (C 6 H 5 ) 4 Pb, and (C 6 H 5 ) 2 Hg to give derivatives CH 3 SO 2 N(C1)M(C 6 H 5 ) n-1 . In these reactions one phenyl group is cleaved from the metal.

119 Sn NMR chemical shifts as well as 1 H 119 Sn and 31 P 119 Sn NMR coupling constants are reported and discussed for compounds of the type [(CH 3 ) 3 Sn] n [ t C 4 H 9 ] 3-n P (n = 1, 2, 3) and related complexes Mn(NO) 3 L, Fe(CO)(NO) 2 L, Co(CO) 2 (NO)L and Ni(CO) 3 L (L = organotin phosphine).

3 ∞ [Al(H 2 PO 4 ) 3 ] has been prepared and characterized as a second modification of aluminium tris(dihydrogenphosphate). Its crystal structure is a three-dimensional Al-O-P network of AlO 6 octahedra, linked by common vertices through O 2 P(OH) 2 tetrahedra with six further octahedra. Each P-OH group is a proton donor as well as a proton acceptor of O-H···O hydrogen bonds arranged in angular chains of alternating polarity in macroscopic domains.

Primary phosphanes, RPH 2 , react with carbonic ester chlorides, ClCOOR′, in the presence of K 2 C0 3 to yield the title compounds RPHCOOR′ and RP(COOR′) 2 . The NMR data of the novel compounds are presented and discussed. Other physical and some chemical properties are described.

The ternary compound β-Li 2 ZnGe was prepared and its structure determined from powder and single crystal data. The compound crystallizes in a modified Na 3 As type structure, space group Ṗ̇̇̇̇̇̇̇̇̇̇̇̇̇̇3̄ m 1 - D 3 3d .The cell parameters are: a = 432.6 pm, c = 1647.0 pm, c/a= 3.83. A phase transition between a-and β-Li 2 ZnGe was found and the reaction of the elements lithium, zinc and germanium to a-Li 2 ZnGe was followed by differential thermal analysis. The temperatures and the enthalpies of transition and fusion were determined.

Benzoato-pyridine-iodine(I) and phthalato-bis(pyridine-iodine(I)) crystallize in the monoclinic spacegroup P2 1 /c. In both cases iodine(I) shows an almost linear coordination towards the pyridine-N and one carboxylate-O donor atom. The I -N distances range from 228 to 232 pm, the I - O distances from 213 to 219 pm. The vibrational spectra contain frequencies in the range 136-145 and 164-175 cm - 1 assigned to the quasi-symmetric and quasi-antisymmetric N-I-O-vibrations. The IR and Ra spectra of the benzoate and phthalate ligands are similar to those of the crystalline benzoic and phthalic acids.

In the context of the synthesis of allenylidene compounds, the reaction of methylpropiolate with a (OC) 5 CrO(C 2 H 5 ) 2 complex was investigated. The species pentacarbonyl- (methylpropiolate)chromium(0) (1), 2,4-bis(methoxycarbonyl)-cyclobut-2-en-1-yliden-1- pentacarbonylchromium(0) (2) and cis-2,4-dimethoxycarbonyl-1,3-butadien-1 -yliden-1 - pentacarbonylchromium (3) were isolated. Attempts to synthesize allenylidene complexes from 1 were unsuccessful. Di-iso-propyl or di-tert-butylallenylidene complexes with chromium or tungsten centers (4a, 4b, 5a, 5b) were finally obtained by the photochemical reaction of pentacarbonylpropargylates, (OC) 5 MC(O)C ≡ CCR 2 O 2- , M = Cr, W, and subsequent desoxygenation. The complexes 4 a, b were characterized as triphenylphosphane adducts, di-iso-propylallenylidenetriphenylphosphorane complexes (6a und 6b). The structure of 6 a was determined by X-ray methods.

The reaction of H 2 Fe(CO) 4 with trimethylphosphite in various stoichiometric ratios is reported. The compounds H 2 Fe(CO) 2 [P(OCH 3 ) 3 ] 2 (stoichiometry of reactants 1:2), H 2 Fe(CO) 3 P(OCH 3 ) 3 (1:1), Fe 3 (CO) 11 [P(OCH 3 ) 3 ], and H 3 Fe 4 (CO) 11 [P(OCH 3 ) 2 ] (3.5:1) were obtained.

Triphenyllead derivatives Ph 3 PbL (HL = glycine, alanine, phenylalanine) and (Ph 3 Pb) 2 L′ (H 2 L′ = aspartic acid) have been prepared from Ph 3 PbOH and the appropriate amino acid. PH 3 Pb-leucinate has been synthesized from Ph 3 PbCl and Tl(I)-leucinate. From IR data structural proposals are inferred: Ph 3 Pb-glycinate is polymeric through monodentate carboxylate and coordinating NH 2 ; Ph 3 Pb-alaninate, -phenylalaninate, and -leucinate contain bidentate carboxylate and non-coordinating NH 2 groups and are probably monomeric. For (Ph 3 Pb) 2 -aspartate and (Me 3 Sn) 2 -aspartate a structure with coordinating NH 2 and mono-and bidentate carboxylate groups is proposed.

The formation of metal ion complexes ML (n-1)+ and ML 2 (n-2)+ of the oxygen tripod ligand L - = cyclopentadienyltris(diethylphosphito-P)cobaltate(l-) with metal ions M n+ = Li + , Na + , K + , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ ,Cd 2+ , Hg 2+ , Pb 2+ , Ag + ,and La 3+ has been studied by pH titration at 25 °C in 95/5 methanol/water solutions kept at an ionic strength of 0.1 by means of tetramethylammonium chloride. The stability of the alkali metal ion complexes increases with decreasing metal ion radii. The sodium complex NaL is more stable than the known crown ether sodium complexes. The K 1 values of the transition metal complexes ML+ are ≈ 10 9 [1/mol]. For H + , Na + , Mg 2+ , and La 3+ the enthalpies and entropies of complex formation have been determined by calorimetric measurements. The results are comparable to those of the tripolyphosphate anion. The complex formation is slightly endothermic and the stability of the complexes arises from a large positive ⊿S of reaction.

C 16 H 18 N 2· 2 C 12 H 4 N 4 , C 40 H 26 N 10 , Mr = 646.7, crystallizes in space group P1̄ with a = 6.843(2), 6 = 7.845(3), c = 16.208(7) Å, α = 84.59(3), β = 81.63(3), γ = 75.75(3)°, V = 832.9 Å 3 , Z = 1, d c = 1.29 Mgm -3 . Final weighted R = 0.107 based on 2894 reflections. The structure consists of stacks of TCNQ π-dimers with interplanar distances of 3.25(1) Å within a dimer and 3.54(1) A between dimers. The phenazine species do not form stacks and show no electronic interaction with adjacent E 2 P or TCNQ molecules.

The total energies, heats of formation (⊿H f ), bond lengths and bond angles of four isomers of S 5 N 5 + (1) have been calculated using the MNDO method. The heart shaped and azulene like structures 1 e and 1 f have been found to be the most stable isomers with about equal energies.

cis-Bis(2-methoxyphenyl)bis(triphenylphosphane)platinum(II) has been synthesized and its molecular and crystal structure determined by X-ray analysis. The structure is discussed with respect to the transition state of the thermal reductive elimination of 2,2′ -bismethoxybiphenyl.

Protected deoxyribonucleotides were identified by field desorption mass spectrometry in eluate fractions from high performance liquid chromatography. The production of abundant cationized molecules and the formation of structural significant fragments by thermally/field induced processes allowed a direct and unambiguous identification of the synthesized products. In addition, indications can be obtained on both organic and inorganic impurities.

By 1 H NMR spectroscopy the stereochemistry of the 1-methyl-1-benzothiepinium ring system was investigated both in thermodynamic and kinetic respects. It was shown that in solution a rapid mutual conversion of the boat shaped seven membered ring system with exo-respectively endo-S-methyl group occurs via a ring inversion and not by a pyramidal inversion at the sulfonium ion. At room temperature predominantly the conformation with the exo-S-methyl group is present.

The cis and trans 2-alkylidene-5-methylcyclohexanones have been separated and distinguished. 2-Benzylidene-5-methylcyclohexanone was also prepared in both forms. The CD, ORD, UV and IR spectra are recorded and discussed. The NMR data include solvent and temperature effects.

The analysis of the protective coating produced during the corrosion of copper in the presence of 2-aminopyrimidine (2-AP) is consistent with the composition [Cu 1+ -2-AP-Cl] n . The individual units form a three-dimensional macro-structure via chloride bridging and hydrogen bonding. The assignment of the structure was supported by NMR, IR, UV and magnetic susceptibüity measurements and an X-ray investigation using the Debye- Scherrer powder method. The thermal behaviour of the coating was studied by massspectral and DTA (differential thermal analysis) methods. Radiochemical experiments were carried out using active copper samples (i.e. containing 64 Cu), or using added 64 CuCl and 64 CuCl 2 in the corrosion of non-active copper both in the presence and absence of added 2-AP. The results elucidate the exchange reactions at the copper surface between dissolved and metallic components. The equilibrium between Cu 2+ and metallic copper on the one hand and 2 Cu 1+ ions on the other is central to the problem, as is also the dissociation of the [Cu 1+ -2-AP-Cl] n complex. The concepts here developed were confirmed by studies of the autoxidation of CuCl and CuO in the presence and absence of 2-AP.

The diastereomeric 2,3-O-[2-phenyl-2-methyl-1,3 dioxalanes] of methyl-α-L-rhamno-pyranosides were synthesised for the first time. The stereochemical characterisation was carried out by X-ray analysis. Evaluation of the X-ray data and comparison with NMR data indicated that the same configuration exists in the crystalline state as in solution.

The electronic absorption (UV/VIS), circular dichroism (CD) and proton magnetic resonance ( 1 H NMR) spectra have been recorded for C-10 epimeric chlorophylls a and a′, pheophytins a and a′ as well as pheophorbides a and a′. Although the epimers in each pair showed virtually identical UV/VIS spectra, their CD spectra were profoundly different and exhibited opposite signs at most wavelengths in the UV region. The differences were interpreted as arising, in part, from different C-10 configurations, and, in part, from conformational alterations induced by the steric strain in the crowded periphery of the macrocycle. The conformational alterations were also clearly indicated by the 1 H NMR Δδ-values observed for the α,β and δ methine protons, the C-10 protons and most methyl group protons of the epimers in each pair. This was considered to imply changes in the geometry of the whole macrocycle. The Δδ-values were larger for the Mg-free epimers than for the chlorophyll epimers, which shows that the central Mg-atom makes the macrocycle more rigid. Correlations between the signs of the CD bands and configurations are discussed.

It is shown that the allomerization of chlorophylls a and b is effectively inhibited by carotenoid pigments. In the light of this finding, two possible mechanisms are considered for the allomerization. One assumes the addition of singlet oxygen to the 9,10-double bond of the chlorophyll (Chl) enolate anion to yield a C-10 hydroperoxide or a dioxetane derivative. The other assumes a free-radical chain reaction involving Chl enolate anion, triplet oxygen, Chl C-10 radicals and peroxide radicals, and Chl C-10 hydroperoxide. The observation that the allomerization and its inhibition by carotenoids occur under carefully controlled dark conditions precluding singlet oxygen formation provides substantial support to the latter mechanism. Further evidence for the free-radical mechanism is obtained by observing the increase of the allomerization rate when air is replaced with pure oxygen from a container. The rate increases to about two-fold in the methanolic Chl solution containing no carotenoid but remains close to zero in the Chl solution containing an equimolar amount of β-carotene. The relevance of the results to photosynthesis and cancer research is briefly discussed.

A 1 H and 13 C NMR spectroscopical study is performed on the basis of 37 1,2,3-selena-diazoles. Besides the discussion of chemical shifts and coupling constants of 1 H and 13 C, selenium satellites were measured providing 1 H 77 Se and 13 C 77 Se coupling constants.

The stereochemistry of the bisaboloids in chamomile-with the exception of bisabolol-oxide C-has been elucidated. The in-vitro-examination of the mutual convertibilities of some bisaboloids gave evidence for the stereochemical accordance of the common chiral centres of all the bisaboloids. The absolute configurations of the remaining third asymmetric carbon atoms in bisabololoxide A and B have been determined by NMR spectrometric studies in comparison with their unnatural semisynthetic epimers. All the stereogenic centres of the bisabololoxides A and B, of (-)-α-bisabolol and of bisabolonoxide A turn out to be S-configurated.

Pyridinium Salts with electron-withdrawing groups in the 3-position react with aliphatic ketoximes under basic conditions to lipophilic addition products, 6-(alkylideniminoxy)-1,6-dihydropyridines.

The structure elucidation of several minor phenazine pigments of Pseudomonads is described. 4-Hydroxyphenazine-1,6-dicarboxylic acid dimethyl ester, 2,3-dihydroxyphenazine, 2,3,7-trihydroxyphenazine, 4-hydroxyphenazine-1-carboxylic acid, 2,3-dihydroxyphenazine-1-carboxylic acid, 2,6-dihydroxyphenazine-1-carboxylic acid and 2,3,7-trihydroxyphenazine-1,6-dicarboxylic acid are new phenazine derivatives. The distribution of phenazines in the genus Pseudomonas is investigated.

Aromatic dithiocarboxylic acids 1 react with imines 4 to give the corresponding adducts 5, aminomethyl dithiocarboxylates, in good yields. The adducts 5 react with phenacyl bromide to give the corresponding phenacyl dithiocarboxy-lates 6.

The compound Au 2 (SeO 3 ) 2 (Se 2 O 5 ) was prepared from gold metal and seienic acid at 553 K. The crystal structure [C2/c, a = 2034.4(5), b = 413.0(1), c = 1325.4(3) pm, β = 115.88(3)°, Z = 4] was refined to R = 0.035. Both gold atoms lie on crystallographic centres of symmetry and show square planar coordination (Au-0 196.9-201.3 pm). The extended structure consists of three cross-linked systems of the form [··· -Au-(selenite or diselenite) -Au-···].