Zur Kenntnis des Faktors F430 aus methanogenen Bakterien: Struktur des proteinfreien Faktors

Factor F430 from Methanogenic Bacteria: Structure of the Protein-free Factor Factor F430, the porphinoid nickel-containing coenzyme of the methylcoenzyme-M reductase of metanogenic bacteria is shown to be the 3³,8³,12²,13³,18²-pentaacid derivative of the pentamethylester F430M, the structure of which had been determined previously (see structural formulae 1 and 2 ). The structure assignment rests on chromatographic, UV/VIS-, CD-, IR-, and ¹³C-NMR-spectroscopic as well as FAB-mass spectral comparision of F430 with F430M and the pentaacid prepared by acid-catalyzed hydrolysis of F430M. In the cells of Methanobacterium thermoautotrophicum, factor F430 is present in a ‘bound’ and also, depending on the growth conditions, in ‘free’ form, the latter being defined as the part of total F430 that can be extracted from the cells under extremely mild conditions (80% EtOH at 0–4°). From the (protein)-‘bound’ form, F430 is extracted by subsequently treating the cells at 0–4° with 80% EtOH containing (e.g.), 2m LiCi. From both sources, the extracted factor is the same pentaacid, and there is no indication for the existence of a protein-free F430 species that would contain additional (covalently bound) structural elements.     

Zur Kenntnis des Faktors F430 aus methanogenen Bakterien: Absolute Konfiguration

Factor F430 from Methanogenic Bacteria: Absolute Configuration Experiments on F430M ( 2 ) aiming at a potentially biomimetic, reductive reconstruction of the F430 ( 1 ) chromophore from corresponding pyrrocorphinate intermediates provided us with F430 derivatives which contain an isobacteriochlorinate chromophore system similar to the one occurring in sirohydrochlorin ( 3 ) (cf. the Scheme). Comparison of their CD spectra with the-CD spectrum of nickel( II )-sirohydrochlorinate octamethyl ester demonstrates that the absolute configurations of factor F430 and sirohydrochlorin in the region of rings A and B are the same.     

Zur Kenntnis des Faktors F430 aus methanogenen Bakterien: Struktur des porphinoiden Ligandsystems

Factor F430 from Methanogenic Bacteria: Structure of the Porphninoid Ligand System A structure is proposed for F430M, a non-cristalline methanolysis product of isolates of the nickel-containing, porphinoid factor F430 from Methanobacterium thermoautotrophicum. Crucial to the structure determination are five incorporation experiments with M. thermoautotrophicum (strain Marburg) in which the specifically mono-¹³C-labeled biosynthetic precursors (2-¹³C), (3-¹³C), (4-¹³C)-, (5-¹³C) ALA (ALA = δ-amino-levulinic acid) and L-(methyl-¹³C)methionine were incorporated into F430 with high efficiency. The ¹³C-NMR,-spectra of the specifically labeled F430M samples derived therefrom, together with the UV./VIS. spectral data of F430M, contain all the information necessary for the deduction of the constitution of the F430M chromophore, assuming the established pattern of porphinoid biosynthesis to be operative in F430 biosynthesis. ¹H-NMR. spectroscopy and, in particular, ¹H-NMR.-NOE-difference spectroscopy corroborates and completes the constitutional assignments and, furthermore, makes possible an almost complete derivation of the molecule's relative configuration. Schemes 3 and 4 summarize the results of ¹H-NMR. spectroscopy, presenting them within the context of the proposed structure for F430M. The assignment of absolute configuration implied in the formula is given preference because of F430M's very close structural and (assumed) biosynthetic relationship to sirohydrochlorin and vitamin B₁₂ (with respect to ring C, the assignment is based on degradative evidence). According to the proposed structure, the nickel complex F430M possesses an uroporphinoid (Type III) ligand skeleton with an additional carbocyclic ring and a chromophore system not previously encountered among natural porphinoids. It can be considered to be a (tetrahydro) derivative of the corphin system, combining structural elements of both porphyrins and corrins.     

Zur Kenntnis der Chemie der Silazane. IV. Über ein Sulfurylphosphazo-silazan

Trichlorophosphazo-sulphurylchloride. Cl₃P?N? SO₂Cl, reacts with heptamethyldisilazane to yield the Si? N? P compound (I) formulated in ?Inhaltsübersicht”?. (I) reacts with PCl₅ or C₆H₅? PCl₄ forming the known 2,2,2,4,4,4-hexachloro-1,3-di-methylcyclo-diphosphazane(II), accompanied by the compound Cl₃P?N? SO₂Cl and C₆H₅? PCl₂?N? SO₂Cl, respectively, which were detected by means of ³¹P-NMR spectroscopy.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XIII. Über die Reaktion von Vanadinsäure-triisopropylester mit Zinkdimethyl—Zur Kenntnis des Methylvanadinoxiddiisopropoxids

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XIII. the Reaction of Vanadium Isopropyl Ester with Dimethyl Zinc. — On the Formation of CH₃VO(i-OC₃H₇)₂ Dimethyl zinc reacts with ortho vanadium acid triisopropyl ester forming methyl zinc isopropoxide (CH₃Zn-i-OC₃H₇)_n and methyl vanadium oxide diisopropoxide CH₃VO(i-OC₃H₇)₂. The new σ-organovanadium compound was isolated and thoroughly characterized.     

Zur Kenntnis der neuen Phosphorsulfidphase P4S9. II. Über verschiedene Methoden zur Darstellung und über die Eigenschaften und Konstitution des P4S9

Both, reaction of red phosphorus, P₄S₃ or P₄S₇ with sulphur, and elimination of sulphur from P₄S₁₀ yield the new phosphorus sulphide phase P₄S₉. This phase exists in two modifications. The properties and constitution of the P₄S₉ phase are described.     

Über die Stereochemie von Zwischenprodukten (Aldolbasen) der Doebner-von Miller-Chinolin-Synthese

In the Doebner-von Miller quinoline synthesis with acetaldehyde or crotonaldehyde two stereoisomeric 4-hydroxy-1, 2, 3, 4-tetrahydroquinaldines are formed as intermediates. The stereochemistry of these compounds differing in the relative positions of the hydroxygroups to the methyl-group can be ascertained by NMR.-spectroscopy. The pK_a-values of stereoisomers are not identical due to the different spacial positions of the HO-groups.     

Zur Kenntnis der Fluoride zweiwertiger Lanthanoide. II. Über die Synthese von MLnF3 aus MLnF4

On Fluorides of Divalent Lanthanoids. II. Synthesis of MLnF₃ from MLnF₄ CsEuF₃, CsYbF₃, and RbYbF₃, which had already been prepared via reduction of the corresponding trifluorides with alkali metal, were also obtained by reducing MLnF₄ with M (M = Cs, Rb, K; Ln = Eu, Yb). No additional alkali fluoroperovskites of lanthanoids were detected either by reduction of LnF₃ or MLnF₄ with metallic Cs, Rb, or K or by other reactions, e.g. 3CsF + 2SmF₃ + Sm. It was shown that the reaction of CsF with EuF₂ (350–850°C) produced only very little CsEuF₃.     

Protonierungs- und Deprotonierungskinetik des Systems Azulen-Azuleniumkation,ein Beitrag zur Kenntnis der Hammett'schen Ho-Aciditätsfunktion

Using a flashphotolysis-method to evaluate the rates of the protonation of azulene and the deprotonation of azuleniumcation as a function of H₀ the validity of the Hammett H₀-function was examined. Using this technique it was possible to obtain information on the behaviour of the activity coefficients and to show that the H_c-acidityfunction of Reagan [1] is a better measure of the hydrogen activity than the H₀-function. The dependence of the deprotonation rate on H₀ is explained as a consequence of the different behaviour of the activity coefficients of Hammett-indicators and azulene/azuleniumcation, respectively.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. IV Über Darstellung und Eigenschaften von Alkyl- und Aryltitantrihalogeniden

Titanium(IV)chloride and bromide react with zinc dialkyls forming the corresponding titanium trihalides. In detail the preparation and charakterisation of methyltitanium trichloride, methyltitanium tribromide, phenyltitanium trichloride and of complexes of proypl-, pentyl- and phenyltitanium trichloride are described. Furthermore some considerations are made on the stabilities of organotitanium compounds.     

Beiträge zur Chemie des Siliciums und Germaniums. XVII. Über die Aufbewahrung von Silanen in Behältern aus Stahl

For the storage of raw silane and silane isomeres isolated by distillation or gaschromatographic separation, 40 Mn 4-steel vessels are proposed. A metallographic analysis of a steel vessel containing silanes over a period of six years shows only a small partiel decarbonization of the material up to a depth of 200–250 μm. Decomposition of the silane was not observed.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XXXII. Über Benzylverbindungen des Kupfers

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXXII. On Benzyl Copper Compounds Benzyl copper is formed reacting copper dichloride or acetylacetonate with dibenzyl zinc complexed by chlorides or acetylacetonates of copper and zinc. The complexes decompose between ?15 and +25°C with separation of copper and benzyl radicals proved by spin trap experiments. The stability of the compound is not influenced remarkably by substituents in o-position but is caused by complex formation with triphenyl phosphine. Pure benzyl copper, obtained by decomposition of BzCu · 0.25 BzZn(acac) · 0.75 Zn(acac)₂ by means of diethyl ether, decomposes spontaneously even at a temperature of ?50°C.     

Über Metall-Stickoxid-Komplexe. XXV. Zur Kenntnis von Nitrosylcyano-Komplexen der Metalle der Eisengruppe

The binuclear nitrosylhalides of iron and cobalt react with cyanide to anionic complexes [M(NO)₂(CN)₂]^? (M = Fe, Co). Substituted monomeric compounds M(NO)₂LBr and Ni(NO)L₂Br lead primarily under replacement of bromide to nonionic complexes M(NO)₂LCN and Ni(NO)L₂CN. In general these complexes react with more cyanide yielding anions [M(NO)₂(CN)₂]^?, [Ni(NO)L(CN)₂]^? and [Ni(NO)(CN)₃]^2?. The paramagnetic dinitrosyliron compounds can be reduced to diamagnetic complexes by Na/Hg. A disproportion reaction of Co(NO)₂P(C₆H₅)₃CN forms a salt [Co(NO)₂ · (P(C₆H₅)₃)₂][Co(NO)₂(CN)₂], a similar salt can be made by the reaction of Na[Co(NO)₂(CN)₂] with [Co(NO)₂(NHP(C₆H₅)₃₂]Br. The IR spectra are discussed.     

Zur Chemie und Strukturchemie der Phosphide und Polyphosphide. 29. Die molaren Volumina von Metall-Phosphiden,ein Beitrag zur Raumchemie der festen Stoffe

Chemistry and Structural Chemistry of Phosphides and Polyphosphides. 29. Molar Volumes of Metal-Phosphides, a Contribution to the “Raumchemie” of Solids After a short introduction into the “Raumchemie” of solids, developed in 1934 by W. Biltz, the behaviour of the molecular volumes of phosphorus in metal phosphides is discussed. In the case of salt-like phosphides the volume increment of phosphorus, V_P, which is obtained after removal of the cation increment, increases with increasing negative charge z_P of the phosphide ions P^z (?0.07 ≥ z ≥ ?3) and on the other hand decreases with increasing cation charge z_M. The relations are shown by the interpolation equation V_P(z_P, z_M) = exp (αz_Pz_M + βz_P + γz_M + δ) with α = 0.046, β = ?0.368, γ = ?0.066, δ = 2.630. There is no observable difference between compounds with A and B metals. Special conditions due to crystal structure and chemical bonding are discussed. Semimetallic phosphides are appropriately discussed on the basis of the volumes of the metals and of increments of semimetallic phosphorus. Here the V_P values lie between 10 and 6 cm³ · mol^?1. They become smaller as the ratio M/P increases. Some examples are given to show that in special cases the volume can be used to judge the type of bonding. The statement of tho theorem of optima1 volumes is explained for a group of salt-like phosphides. Our study shows, that the “Raumchemie” of BILTZ reliable on the field of metal phosphides.     

Über Oxocobaltate der Alkalimetalle. Zur Kenntnis von Li8CoO6

Oxocobaltates of Alkali Metals. On Li₈CoO₆. Hitherto unknown Li₈CoO₆, rubin- red single crystals, cristallizes according to WEISSENBERG and precession photographs (MoK_α) hexagonal with a = 5.44 Å, c = 10.87 Å; c/a = 2.0; Z = 2, space group C? P6₃cm. Atomic parameters see text. The structure derives from a closest packing of O^2?, ABACA … (The tetrahedral, ?isolated”? groups [CoO₄] show remarkable short distances Co–O (1.66 Å), comparable with [CoO₄] in Li₄CoO₄, being isotypic with Li₄SiO₄. The MADELUNG Part of Lattice Energy is calculated and discussed.     

Über Erdalkalimetalloxogallate. II. Zur Kenntnis von SrGa4O7

SrGa₄O₇ was prepared, and studied by single crystal x-ray investigations. It is isotypic with CaAl₄O₇ and CaGa₄O₇; space group C⁶_2h – C2/c a = 13.46, b = 9.19, c = 5.69 Å, β = 105.8°). Sr²⁺ as well as Ca²⁺ is surrounded by five oxygen ions in a trigonal-bipyramidal array.