Volume 36, Issue 6

The solvolysis of (CO) 5 CrPCl 3 with N 2 H 4 or H 2 N-N(CH 3 ) 2 yields (CO) 5 CrP(NH-NH 2 ) 3 and (CO) 5 CrP[NH-N(CH 3 ) 2 ] 3 respectively containing the hitherto unknown and unstable ligands P(NH-NH 2 ) 3 and P[NH-N(CH 3 ) 2 ] 3 . Their constitution is derived from spectroscopic data.

The explosive nitrido azido complexes MoN(N 3 )Cl 2 · py and MoN(N 3 ) 3 py are prepared by the reaction of MoCl 4 (py) 2 with (CH 3 ) 3 SiN 3 in 1,2-dichloroethane. Both compounds hydrolyze quickly in moist air. After separation of the insoluble, black MoN(N 3 )Cl 2 · py from the solution of MoN(N 3 ) 3 py, the latter can be obtained in form of monoclinic, red crystals of the space group C2/c. Its structure consists of monomeric complexes, wherein the Mo atom has a square pyramidal coordination. The nitrido ligand occupies the apex and forms a strong multiple bond of 163.4 pm to the Mo atom. σ-Bonds of different strength exist between the Mo atom and the basal ligands: MO-N 3 - 204.3 pm; Mo-py = 225.8 pm. The α-N atoms of the azido groups are sp 2 hybridized, with their lone pair pointing away from the nitrido ligand. The pyridine ligand forms an angle of 61.6° to the basal plane of the coordination polyhedron.

The cleavage of element-element bonds in ligands of the type R 2 EER′ 2 and R 2 EE′R′ (R, R′ = CH 3 , CF 3 ; E = P, As; E′ = S, Se, Te) coordinated to M(CO) 5 -fragments (M = Cr, Mo) by Me 3 SnH (Me = CH 3 ) has been studied in some detail by NMR spectroscopic measurements ( 1 H, 19 F). In comparison with the analogous reactions of the free ligands, the rate of reaction is considerably reduced, wheras the cleavage direction is generally retained. Possible reaction intermediates have been synthesized by independent routes and tested under comparable conditions.

The title complex, IrCl(bdpp) (1), where bdpp = PhP[(CH 2 ) 3 PPh 2 ] 2 , has been obtained from [IrCl(C 8 H 14 ) 2 ] 2 and the triphosphine ligand. Characteristic 31 P NMR data of 1 dissolved in THF are δ(P̲Ph 2 ) = 2.7 and δ(P̲Ph) = - 19.9 with cis- 2 J(P̲IrP̲) = 32.8 Hz. Reaction of 1 with CO proceeds stepwise to yield five-coordinate IrCl(CO)(bdpp) (2) and ionic [Ir(CO) 2 (bdpp)]Cl (3). A trigonal bipyramidal geometry with equatorial CO ligands is assigned to the cation of 3 on the basis of its v(CO) infrared intensities. When allowed to react with HCl, 1 gives the monohydride IrHCl 2 (bdpp) (4). Similarly, the dihydride IrH 2 Cl(bdpp) (5) is formed from 1 and H 2 . As has been established by IR and NMR spectroscopy, 4 and 5 adopt cis-mer-octahedral structures.

The alkyls MR 3 (M = B, AI, Ga, In) react with pyrazine (Pz) and sodium in THF to yield persistent radical complexes Pz(MR 2 ) 2 · + MR 4 - (1). Use of TIR 3 leads to rapid deposition of thallium metal. The formation of these ionic complexes 1 is the result of MR 3 dissociation into + MR2 and -MR 4 ions. All radicals have been identified and characterized by ESR; the data reveal the influence of back bonding in the boron derivative.

The kinetics and the mechanism of a reversible, intramolecular conversion of a coordinated nitrosyl ligand into a probably O,N-coordinated hydroxylamido(1-) ligand is reported for the complex anion [V(tha)(NO)(H 2 O)] - (tha = 1,1′,1″-nitrilo-tris-2-propanol). Mechanisms for the formation of nitrosyl complexes of the type {V-N=O} 4 generated from hydroxylamine and complexes of vanadium in the oxidation states + V or + III, respectively, are proposed.

The new compound Tl 2 Sn 2 S 5 was prepared by fusion of a stoichiometric mixture of the elements followed by prolonged heating at 300 °C. The compound crystallizes in the monoclinic system in space group C2/c with lattice constants a - 11.115(2), 6 = 7.723(1), c = 11.492(2) Å, and β = 108.60(1)° (Z = 4). The Sn atoms are coordinated by five S atoms forming a considerably distorted trigonal bipyramid (mean distance Sn-S: 2.497 Å). By common edges the SnS 5 bipyramids are linked into chains extending in the [110] and [11̄̄0] directions, respectively. The chains are cross-linked by sharing the remaining equatorial vertices of the SnSs bipyramids, thus forming a three-dimensional framework which is related to that described for Na 4 Sn 3 S 8 [1]. The Tl atoms located in channels running parallel to the b axis are surrounded by nine S atoms. The distances Tl-S vary from 3.073 to 3.897 Å.

In the course of the hydrolysis of tris(alkoxy)boranes B(OR) 3 (R = methyl, n-butyl, or 2-ethylhexyl) with a small amount of water in organic solvents, both possible intermediates (RO) 2 BOH and ROB(OH) 2 have been unambiguously identified by Raman spectroscopic measurements. Lines have been found for (CH 3 O) 2 BOH at 772.8 cm -1 and for CH 3 OB(OH) 2 at 814.6 cm -1 . The compounds are in equilibrium with the starting material B(OCH 3 ) 3 and the product B(OH) 3 . Potentiometrie and conductometric investigations likewise indicate the existence of these species. A mechanism of the hydrolysis reaction is based on kinetic considerations. With hydroxide ions in non-aqueous solvents or aqueous hydroxide ions the hydrolysis reactions occur differently because in the first case the end product of the hydrolysis is the orthoborate ion [B(OH) 4 ]-, whereas in the second case in concentrated aqueous solutions poly borates are formed.

The preparation, for the first time, of the deprotonated complexes of oxamic acid with Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Dy(III), Ho(III) and Yb(III) is reported. Properties, analytical results, conductometric measurements, magnetic moments and spectral data (IR and diffuse reflectance spectra) are discussed in terms of possible structural types and the nature of the bonding. Oxamic acid acts as a bidentate non-bridging ligand.

NMR parameters [chemical] shifts (δ 11 B, δ 13 C) and coupling constants ( 1 J( 13 C 1 H), 1 J( 13 C 11 B), 1 J( 13 C 13 C), 1 J( 11 B 11 B) of closo-pentaalkyl-1,5-dicarbapentaboranes(5) were determinated by 10 B, 11 B, and 13 C NMR spectroscopy. The magnitudes of 1 J( 13 C 11 B) and 1 J( 13 C 13 C) correspond to 1 J( 11 B 1 H), 1 J( 13 C 11 B) and 1 J( 13 C 1 H) in the parent compound 1,5-C 2 B 3 H 5 . According to predictions from MO calculations 1 J( 11 B 11 B) was found to be < 10 Hz. Together with these data the δ 11 B and δ 13 C values show that neither the structure nor the bonding situation in the polyhedron are significantly affected by alkyl substitution.

The reactions of pentacarbonyl manganese bromide and pentacarbonyl rhenium bromide with di(tert-butyl)trimethylsilyl phosphine, teri-butyl-bis(trimethylsilyl)-, -(germyl)-, -(stannyl) phosphine, as well as with tris(trimethylsilyl)-, -(germyl)-, and -(stannyl) phosphine result in the elimination of one CO ligand and the formation either of corresponding bromo-tetracarbonyl(organometalphosphine)manganese or -rhenium complexes or of corresponding octacarbonyl-bis(μ-organometalphosphido)dimanganese or -dirhenium complexes. The IR, NMR, and Mössbauer spectra are reported and discussed.

The corrosion of copper granules under controlled conditions (2.5% NaCl solution, pH 4 buffer, O 2 ) was studied using a) the rate of uptake of oxigen and b) the pH stat method. Cu 2+ ions catalyse the corrosion of copper. The surface area of the copper and the temperature influence the rate of corrosion in the expected manner. Experiments in light and dark showed little variation in the results. The results obtained by measuring the O 2 uptake and using the pH stat method were confirmed and complemented by electrochemical measurements. (Steady potential/time curves, current/voltage curves, measurement of the polarisation resistance and estimation of Cu 2+ during corrosion via a Cu 2+ sensitive electrode.) The influence on the corrosion of F - , CI - , Br - and I - , mineral acid concentration and other inorganic ions was also studied under standard conditions. To ensure the correctness of the interpretation of the results (see reaction scheme), the autoxidation of CuCl and CU 2 O was also studied under standard conditions. The experimental results are consistent with the steps (1)-(4) in the reaction scheme. The fastest step is clearly the oxidation of Cu 1+ , which is continuously supplied via the copper surface. The interpretation here presented forms the basis for the understanding of the inhibition of corrosion exhibited by a number of organic compounds.

N-Substituted (Z)-5-benzylidenetetramic acids undergo isomerisation to E/Z mixtures on treatment with acids or methylate.

The crystal structure of 2-deoxy-β-D-enrythro-pentopyranose (1) was reexamined by X-ray crystallographic studies. In crystalline 1, a radiation-induced chain reaction occurs with the only product being, 2,5-dideoxy-D-enrythro-pentonic acid (4). In the chain propagating step leading to 4, an H atom is transferred over a distance of ≤ 3.3 Å as taken from interatomic distances in the unperturbed crystal. The crystal structure clearly indicates the direction by which the chain reaction proceeds through the crystal. The strong temperature dependence of G(4) is discussed in terms of temperature effects on chain initiation, propagation and termination rates.

Phosphate Production, Hydroxylamine, ATP Saygin and Decker [6, 7] have reported that the formation of hydroxamic acids in solutions containing ATP, MgCl2, hydroxylamine and an acidic acceptor (acetic acid or amino acids) is not accompanied by the release of inorganic phosphate from ATP. Using an ion exchange chromatography method developed by Lowenstein [8] to separate the various components of such reaction mixtures, we now show that inorganic phosphate, as well as some pyrophosphate, is produced during incubation at 50 °C. Evidence is also presented to indicate that the failure of Saygin and Decker [6, 7] to detect phosphate is due to a total inhibition of their phosphate assay system by ATP.

The applicability of solvent induced circular dichroism (SICD) for the conformational analysis of bile pigments has been investigated. The S-(-)-ethyl lactate induced rotational strengths for octaethylbilindion (4) and its dihydroderivative 5 are remarkably high. Related compounds, e.g. the isomeric purpurines 1 and 2 and formyltripyrrinon 3 exhibit an optical activity which is smaller by more than one order of magnitude. 1-3 are essentially free from steric strain so that a flat arrangement of the chromophore is most likely. On the other hand the closed conformations of 4 and 5 experience considerable steric repulsion of their terminal rings, so that a helical topology is energetically favoured. This distinction is reflected in the magnitude of the SICD observed and demonstrates its applicability for the conformational analysis of bile pigments.

The reaction of 3-aryl- or alkylsubstituted 4-hydroxy-2-quinolones or 4-hydroxycoumarins (3a-k) with benzoylchloride afforded the 4-benzoyloxy-2-quinolones or 4- benzoyloxycoumarines 2a-k. Only in one case the 3,3-disubstituted quinolinedione 4 has been isolated, which rearranges to 2a under thermal or basic conditions.

The quaternary 3-cyano-quinolinium salt (1b) reacts in aqueous buffer solution (pH 7.5-12) to oxy-di(1.4-dihydroquinoline) (7), which gives on addition of alcohols or oximes in high yields the alcoxy-dihydroquinolines (8a-c) or dihydroquinolyl-oximethers (8d-f).

Succinyl derivatives of adenosine are synthesized by direct reaction with succinic anhydride catalyzed by 4-morpholine N,N′-dicyclohexylcarboxamidine under kinetic or thermodynamic conditions and partial hydrolysis. Derivatives obtained were N 6 -succinyl adenosine, N 6 ,5′-O-disuccinyl adenosine, 3′(2′)-O-succinyl adenosine, N 6 , 3′(2′)-O-di-succinyl adenosine and 3′(2′),5′-O-disuccinyl adenosine. The last three derivatives were crystallized and gave equilibrium mixtures of 2′-O-and 3′-O-isomers in aqueous solvents with the 3′-O-isomer prevailing. Differentiation of isomers was done by PMR. A mechanism for isomerisation is proposed. The products were purified by anion exchange chromato-graphy and desalting. The procedures are useful for pharmacological applications because of the purity and yield of products.

Based on a discovery of trans-3-hexenal and participation of isomerases and non-enzymatic isomerizing factors, the biogenetic pathway of trans-2-hexenal (leaf aldehyde) and cis-3-hexenol (leaf alcohol) has been demonstrated.

Low molecular weight constituents of 3400 venom sacs of Paravespula vulgaris were extracted with water, diluted acetic acid, and methanol. After conversion to volatile derivatives carbohydrates, amino acids, fatty acids, other constituents of phospho lipids, and biogenic amines were identified by gas chromatography and mass spectrometry. Quantitative analysis was achieved for amino acids by amino acid analysis and for glucose by an enzymatic assay. Results are discussed with regard to biosynthesis of wasp toxins and phylogenetic aspects of hymenopteran venoms.

The solvent effect on the v(N-H) amide I and amide II IR bands of N-methylacetamide were investigated. The frequency shifts could be related to the solvent donor and acceptor num-bers by mean of a two parameters relationship that accounts for the mutual influence between the two interacting sites of the amide.

An X-ray crystallographic study of geminal tetrachlorobis(triphenylphosphazenyl)cyclotriphosphazatriene reveals Type II conformation of both triphenylphosphazenyl groups with respect to the P-N ring. These results are consistent with 31 P NMR data. The phosphazene ring has a distorted chair conformation.

σ-C 3 H 5 · Mn(CO) 5 reacts with bis(diphenyl-phosphino)-N-methyl maleic anhydride to form a complex in which the C 3 H 5 -ligand migrates from the coordination sphere of Mn to the phosphine ligand. The high yield (70%) suggests that this reaction takes place within the coordination sphere of Mn. The product (X-ray analysis) shows unusual bonding properties.

It is demonstrad by means of various mass spectrometric techniques that the dissociative ionization of N.N-bis-silylated hydroxylamine derivatives (5a) and (5b), giving rise to the cleavage of the (O-C) bond, is anchimerically assisted by migration of the trimethylsilyl group to the ether oxygen, thus generating ion (7).