Täuschend einfache 1H-NMR-Spektren bei symmetrisch aufgebauten,zwei Phosphoratome enthaltenden organischen Verbindungen

The ¹H-NMR spectra of symmetric compounds with two phosphorus atoms of the type R? X? P? Y? P? X? R, R = CH₃, C₂H₅, X = —, O, NCH₃, NCH₂—, Y = NCH₃, have been determined. After elimination of eventual couplings within the alkyl protons these spectra always show triplets in the case of trivalent phosphorus and doublets in the case of pentavalent phosphorus atoms. Since this paper establishes an unequal coupling between the alkyl protons and the two phosphorus nuclei, it is concluded that these compounds show a degenerate, however deceivingly simple, coupling: The spectra of symmetric diorgano diphosphines can be interpreted via the same mechanism. Calculations to substantiate these findings are reported.     

Synthesis,characterization, and structures of 1-(9-Fluorenyl)-germatrane and 1-(Phenylacetylenyl)germatrane

Syntheses of the title compounds, viz. N(CH₂CH₂O)₃GeY ( 2 Y?Fluorenyl; 4 Y?PhC?C) by the reaction of X₃GeY ( 1 Y?Fluorenyl, X?Br; 5 Y?PhC?C, X?Cl) with N(CH₂CH₂OSnR₃)₃ ( 3 R?Et; 6 R?Bu) are reported including the preparation of the new compound 1 . Identity and structures were established by elemental analyses, ¹H and ¹³C NMR spectroscopy. 2 and 4 were characterized by mass spectrometry. Single crystal structures of 1 , 2 and 4 were determined by X-ray diffraction methods.     

β-Alkoxycarbonyl Alkyl Tin Chelates 2. Dithizonates – Preparation and Spectroscopic Studies

Dithizone forms stable complexes with β-alkoxycarbonyl ethyl tin chlorides (the so called “Estertins” – a unique class of PVC stabilizer). Reduction of Lewis acidity of the resulting organotin chloride can improve the efficiency of a stabilizer and therefore the β-alkoxycarbonyl ethyl tin dithizonates are likely to show PVC stabilization property. A number of β-alkoxycarbonyl ethyl tin dithizonates of the types R₂SnL₂, R₂SnLX, and RSnL₂X where R = CH₃OCOCH₂CH₂–, C₄H₉OCOCH₂CH₂–, and CH₃OCOCH(CH₃)CH₂–; X = Cl, SCN and L = Dithizone (i. e. 1,5-diphenyl thiocarbazone) and one complex (CH₃OCOCH₂CH₂)₂SnL′Cl where L′ = Diphenylcarbazone have been prepared and characterized by elemental analysis, electronic, IR and PMR spectral data. Possible structural features of the isolated complexes have also been discussed. Preliminary evaluation of the complex (CH₃OCOCH₂CH₂)₂Sn(HDz)₂ as a PVC stabilizer has also been reported.     

IR-spektroskopische Untersuchungen an Halogenmethyl-, Benzyl- und α-Halogenbenzyl-Substituierten Alkoxysilanen,Phenoxysilanen und Disiloxanen

I.R.-spectroscopic Investigation on Halogenomethyl-, Benzyl-, and α-Halogenobenzyl-substituted Alkoxysilanes, Phenoxysilanes, and Disiloxanes Frequencies of Si? O-characteristic vibrations and the relative basicity of oxygen have been measured for Si? O compounds of the type X(CH₃)₂Si? OY (X = halogenomethyl, benzyl, α-halogenobenzyl; Y = alkyl, phenyl, Si(CH₃)₂X). With exception of the less Si? O-characteristic C? O? (Si)-stretching vibration of alkoxysilanes the observed data show a significant dependence from the inductive effect of substituents at Si. There are no informations on conjugative interactions between Si and β-standing halogeno or phenyl groups.     

Zweikernige Palladium(II)‐, Platin(II)‐ und Iridium(III)‐Komplexe von Bis[imidazol‐4‐yl]alkanen

Dinuclear Palladium(II), Platinum(II), and Iridium(III) Complexes of Bis[imidazol‐4‐yl]alkanes The reaction of bis(1,1′‐triphenylmethyl‐imidazol‐4‐yl) alkanes ((CH₂)_n bridged imidazoles L(CH₂)_nL, n = 3–6) with chloro bridged complexes [R₃P(Cl)M(μ‐Cl)M(Cl)PR₃] (M = Pd, Pt; R = Et, Pr, Bu) affords the dinuclear compounds [Cl₂(R₃P)M–L(CH₂)_nL–M(PR₃)Cl₂] 1 – 17 . The structures of [Cl₂(Et₃P)Pd–L(CH₂)₃L–Pd(PEt₃)Cl₂] ( 1 ), [Cl₂(Bu₃P)Pd–L(CH₂)₄L–Pd(PBu₃)Cl₂] ( 10 ), [Cl₂(Et₃P)Pd–L(CH₂)₅L–Pd(PEt₃)Cl₂] ( 3 ), [Cl₂(Et₃P)Pt–L(CH₂)₃L–Pt(PEt₃)Cl₂] ( 13 ) with trans Cl–M–Cl groups were determined by X‐ray diffraction. Similarly the complexes [Cl₂(Cp*)Ir–L(CH₂)_nL–Ir(Cp*)Cl₂] (n = 4–6) are obtained from [Cp*(Cl)Ir(μ‐Cl)₂Ir(Cl)Cp*] and the methylene bridged bis(imidazoles).     

Bis(trimethylsilyl)-hypophosphit und Alkoxycarbonylphosphonigsäure-bis(trimethylsilyl)ester als Schlüsselsubstanzen für die Synthese von Organophosphorverbindungen

Bis(trimethylsilyl)hypophosphite und Alkoxycarbonylphosphonous Acid Bis(trimethylsilyl) esters as Building Blocks in Organophosphorus Chemistry The oxidation of pure bis(trimethylsilyl)hypophosphite ( BTH ) with chalcogenides forming (Me₃SiO)₂P(X)H (X = O, S, Se, Te) is described as well as its reactions with alkylhalides RX (X = Cl, Br, I) and Cl? C(O)OR (R = Me, Et, Bzl). By reaction with oxygen, sulfur, and selenium the alkoxycarbonylphosphonous acid bis(trimethylsilyl)esters form RO? C(O)? P(X)(OSiMe₃)₂ (X = O, S, Se) whereas with Cl? C(O)OR the bis(alkoxycarbonyl)-phosphinic acid trimethylsilylesters are obtained. After partial hydrolysis the resulting instable RO? C(O)? P(O)H(OSiMe₃) gives RO? C(O)? P(O)(OSiMe₃)? CH₂? NH? A? COOR′ (A = CH₂, CH₂CH₂, CHCH₃, CH₂CH₂SH, CHCH(CH₃)₂,…) when allowed to react with hexahydro-s-triazines of the aminoacid esters. Reactions of the alkoxycarbonyl-P-silylesters with NaOR or NaOH result in the corresponding mono-, di-, or trisodium salts. With mineral acids decarboxylation occurs, but H? P(O)(OH)? CH₂? NH? A? COOH can be obtained, too. The structure of the compounds described are discussed by their n.m.r. data.     

Neutral Penta‐ and Hexacoordinate Silicon(IV) Complexes Containing Two Bidentate Ligands Derived from the α‐Amino Acids (S)‐Alanine, (S)‐Phenylalanine,and (S)‐tert‐Leucine

The neutral hexacoordinate silicon(IV) complex 6 (SiO₂N₄ skeleton) and the neutral pentacoordinate silicon(IV) complexes 7 – 11 (SiO₂N₂C skeletons) were synthesized from Si(NCO)₄ and RSi(NCO)₃ (R=Me, Ph), respectively. The compounds were structurally characterized by solid‐state NMR spectroscopy ( 6 – 11 ), solution NMR spectroscopy ( 6 and 10 ), and single‐crystal X‐ray diffraction ( 8 and 11 were studied as the solvates 8? CH₃CN and 11? C₅H₁₂ ? 0.5 CH₃CN, respectively). The silicon(IV) complexes 6 (octahedral Si‐coordination polyhedron) and 7 – 11 (trigonal‐bipyramidal Si‐coordination polyhedra) each contain two bidentate ligands derived from an α‐amino acid: (S)‐alanine, (S)‐phenylalanine, or (S)‐tert‐leucine. The deprotonated amino acids act as monoanionic ( 6 ) or as mono‐ and dianionic ligands ( 7 – 11 ). The experimental investigations were complemented by computational studies of the stereoisomers of 6 and 7 .     

Synthese „anorganischer”︁ Tintenfisch-Moleküle. II

Synthesis of “Inorganic” Pode-type Molecules. II The reaction of the amino compounds Me_yB? NMe₂ (B ? As, y ? 2; B ? Si, y ? 3) with 1, n-dioles results in the formation of the compounds HO(CH₂)_nOBMe_y. These compounds can be used as the arms of pode-type molecules Me_xA[? O(CH₂)_nOBMe_y]_z with A ? Si, As. The influence of A, B, n, and z in the rearrangement of these molecules is examined. A second type of pode molecules can be prepared by the reaction of Me₂As? R? OH (R ? CH₂CH₂, CH₂CH₂(OCH₂CH₂)₂) with the amino compounds Me_x(NMe₂)_z (A ? As, Si). These reactions result in the formation of molecules as Me_xA(ORAsMe₂)_z.     

Polymerization of ethylene with nickel α-diimine catalysts

Several nickel α-diimine compounds of the general formula (ArNC(R) C(R)NAr)NiX₂ (Ar = 2,6-alkyl substituted Ph, R = H or CH₃, X = Br or CH³) were tested in ethylene polymerization after activation with different co-catalysts, such as methylaluminoxane, Al(C₂H₅)₂Cl or other aluminium alkyls, and ionizing reagents like B(C₆F₅)₃, [CPh₃][B(C₆F₅)₄] or HBF₄. The performances of the different catalytic systems were compared with reference to polymer productivity and structure. The degree of branching of the obtained polyethylenes was shown to depend not only on the ligand environment at the Ni centre but also on the type of co-catalyst.     

Phosphoniumsalze mit Hydrogendihalogenidanionen HCl2−, HBr2− Hl2− oder HBrCl−

Phosphonium Salts with Hydrogen Dihalide Anions HCl₂^?, HBr₂^?, HI₂^?, or HBrCl^? Phosphonium hydrogen dihalides [R₃PR′][XHY] (X = Y = Cl, Br, I; X = Br, Y = Cl) resp. [R₃PH]HBr₂ are obtained as extremely hydrolyzable crystals by reaction of phosphonium halides or tertiary phosphanes with hydrogen halide. According to IR spectroscopic results the solid compounds mostly contain anions [XHX]^? with symmetric hydrogen bonds. In solution ¹H NMR measurements show a slight (X = Cl, Br) or considerable (X = I) dissociation according to HX₂^? ? X^? + HX. On heating the solid compounds decompose with formation of hydrogen halide and [R₃PR′]X or [R₃PH]X. In this process the hydrogen bromidechlorides [R₃PR′][BrHCl] exclusively eliminate HCl. NMR studies (¹H und ³¹P) with solutions containing [R₃PH]HBr₂ (R = phenyl, 1-naphtyl) or HBr and Ph₃P in varying molar ratios show that a fast proton exchange between the competing Lewis bases R₃P and Br^? exists.     

3‐Rhoda‐1,2‐diazacyclopentanes: A Series of Novel Metallacycle Complexes Derived From CN Functionalization of Ethylene

Rh‐containing metallacycles, [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NR)₂‐]Cl; TPA=N,N,N,N‐tris(2‐pyridylmethyl)amine have been accessed through treatment of the Rh^I ethylene complex, [(TPA)Rh(η²‐CH₂CH₂)]Cl ([ 1 ]Cl) with substituted diazenes. We show this methodology to be tolerant of electron‐deficient azo compounds including azo diesters (RCO₂N?NCO₂R; R=Et [ 3 ]Cl, R=iPr [ 4 ]Cl, R=tBu [ 5 ]Cl, and R=Bn [ 6 ]Cl) and a cyclic azo diamide: 4‐phenyl‐1,2,4‐triazole‐3,5‐dione (PTAD), [ 7 ]Cl. The latter complex features two ortho‐fused ring systems and constitutes the first 3‐rhoda‐1,2‐diazabicyclo[3.3.0]octane. Preliminary evidence suggests that these complexes result from N–N coordination followed by insertion of ethylene into a [Rh]?N bond. In terms of reactivity, [ 3 ]Cl and [ 4 ]Cl successfully undergo ring‐opening using p‐toluenesulfonic acid, affording the Rh chlorides, [(TPA)Rh^III(Cl)(κ¹‐(C)‐CH₂CH₂(NCO₂R)(NHCO₂R)]OTs; [ 13 ]OTs and [ 14 ]OTs. Deprotection of [ 5 ]Cl using trifluoroacetic acid was also found to give an ethyl substituted, end‐on coordinated diazene [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NH)₂‐]⁺ [ 16 ]Cl, a hitherto unreported motif. Treatment of [ 16 ]Cl with acetyl chloride resulted in the bisacetylated adduct [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NAc)₂‐]⁺, [ 17 ]Cl. Treatment of [ 1 ]Cl with AcN?NAc did not give the Rh?N insertion product, but instead the N,O‐chelated complex [(TPA)Rh^I ( κ²‐(O,N)‐CH₃(CO)(NH)(N?C(CH₃)(OCH?CH₂))]Cl [ 23 ]Cl, presumably through insertion of ethylene into a [Rh]?O bond.     

Neue Synthesewege für Organohalogenstibane

New Methods for Synthesis of Organohalogenostibanes Organohalogenostibanes RSbX₂ (R = CH₃, C₆H₅; X = Cl, Br) and R₂SbX (R = C₆H₅; X = Cl) are received in good yields by alkylation or arylation of the corresponding antimony halides with Pb(CH₃)₄, Sn(CH₃)₄, Sb(CH₃)₃, or Sb(C₆H₅)₃. These methods are better than those, described in the literature for preparation of the compounds.     

Zur Kenntnis der Organophosphorverbindungen. XV. Darstellung und Reaktionen von Trimethylsilylestern der Phosphinsäuren

On Organophosphorus Compounds. XV. Preparation and Reactions of Trimethylsilyl Esters of Phosphinic Acids Trimethylsilylesters of Phosphinic acids R₂P(X)YSi(CH₃)₃ (R ? CH₃, C₂H₅, C₃H₇, t?C₄H₉, C₆H₅; X, Y ? O, S) were prepared by 7 different methods as in some cases easily hydrolysable but thermally remarkably stable compounds. The properties and some reactions of these substances are reported, their structures confirmed by IR? as well as ¹H- and ³¹P-NMR-spectroscopy. Dimethylsilylen-bis(phosphinic acid esters) were obtained according to \documentclass{article}\pagestyle{empty}\begin{document}$ 2{\rm R}_{2} {\rm P(\rm X)\rm ONH}_{4} + {\rm R}_{\rm 2} {\rm SiCl}_{2} \to 2{\rm E NH}_{4} {\rm Cl + R}_{2} {\rm P(X) - O - SiR}_{2} - {\rm O - P(X)R}_{2} ({\rm R = CH}_{3};{\rm X = O,S}) $\end{document}.     

A New Approach to the Design of Neutral 10‐C‐5 Trigonal‐Bipyramidal Carbon Compounds: A “π‐Electron Cap” Effect

DFT (B3LYP, M06‐2X) and MP2 methods are applied to the design of a wide series of the potentially 10‐C‐5 neutral compounds based on 6‐azabicyclotetradecanes: XC¹(YCH₂CH₂CH₂)₃N 1 – 3 , XC¹(YC₆H₄CH₂)₃N 4 – 6 , XC¹[Y(tBuC₆H₃)CH₂]₃N 7 – 9 and carbatranophanes 10 – 25 (X=Me, F, Cl; Y=O, NH, CH₂, SiH₂; Z=O, CH₂, (CH₂)₂, (CH₂)₃). Carbatranophanes 10 – 25 are characterized by a sterical compression of their axial 3c–4e XC¹←N fragment with respect to that in the parent molecules 4 – 6 . A magnitude of the revealed effect depends on a valence surrounding of the central carbon atom C¹, the size and the nature of the side chains (Z) that link the “π‐electron cap” with a tetradecane backbone. This circumstance allowed us to obtain 10‐C‐5 structures with the configuration of the bonds around the C¹ atom, which corresponds to practically an ideal trigonal bipyramid. In these compounds, the values of the covalence ratio χ of approximately 0.6 for the coordination C¹←N contacts with a covalent contribution (atoms in molecules (AIM) and natural bond orbital (NBO)) are record in magnitude. These values lie close to a low limit of the interval of the χ_Si←D change (0.6–0.9) being characteristic of the dative and ionic‐covalent (by nature) Si←D bond (D=N, O) in the known 10‐Si‐5 silicon compounds.     

Synthesis and reactivity of ω-haloalkyltin compounds

ω-Haloalkyltin trihalides, X(CH₂)_nSnX₃ (n ≧ 3; X = halogen) can readily be prepared in high yields by the direct reaction of stannous halides with α,ω-dihaloalkanes, catalysed by trialkylantimony compounds. The compounds are versatile starting materials for the synthesis of a variety of ω-functionallysubstituted organotin compounds R_3-mX_mSn(CH₂)_n Y (R = alkyl, phenyl; m = 0-3; X = Cl, Br, O; Y = Br, NMe₂, NEt₂, COOH, CHOHR, R₃Sn). ¹H-NMR spectral data for a series of such compounds are presented. The trends observed in the chemical shifts and the ¹¹⁹Sn—methyl proton coupling constants of Me_3-m Br_mSn(CH₂)_nBr (m = 0-3; n = 3-5) are discussed in terms of inductive effects. Intramolecular coordination between the ω-bromine atom and tin could not be demonstrated.     

C,N‐chelated triorganotin(IV) diesters of 4‐ketopimelic acid and their fungicidal activity

The set of four triorganotin(IV) diesters of 4‐ketopimelic acid containing {2‐[(CH₃)₂NCH₂]C₆H₄}‐ as a C,N‐chelating ligand was prepared. Their structures were studied by the help of IR, NMR and X‐ray crystallographic techniques in the case of {{2‐[(CH₃)₂NCH₂]C₆H₄}SnPh₂}₂[(OOCCH₂CH₂)₂C?]. All these compounds are monomeric both in solid state and solution with five‐coordinated tin atoms and medium strong intramolecular Sn? N connection. The antimycotical activity of these compound was studied and compared with the triorganotin(IV) derivatives of 4‐ketopimelic acid and antimycotical drugs in clinical use. Copyright © 2008 John Wiley & Sons, Ltd.     

N‐Heterocyclic Carbene Stabilized Boryl Radicals

The reaction of the 2‐(trimethylsilyl)imidazolium triflate 9 with diarylboron halides (4‐R‐C₆H₄)₂BX (R=H, X=Br; R=CH₃, X=Cl; R=CF₃, X=Cl) afforded the NHC‐stabilized borenium cations 10 a – c . Cyclic voltammetry revealed a linear correlation between the Hammett parameter σ _p of the para substituent and the half‐wave potential. Chemical reduction with decamethylcobaltocene, [(C₅Me₅)₂Co], furnished the corresponding radicals 11 a – c ; their characterization by EPR spectroscopy confirmed the paramagnetic character of 11 a – c , with large hyperfine coupling constants to the boron isotopes ¹¹B and ¹⁰B, while delocalization of the unpaired electron into the NHC is negligible. DFT calculations of the percentage of spin density distribution between the carbene (NHC) and the boryl fragments (BR₂) revealed for 11 a – c a spin density ratio (BR₂/NHC) of ca. 9:1, which underlines their distinct boryl radical character. The molecular structure of the most stable species 11 c was established by X‐ray diffraction analysis.     

1,1‐Ethylboration of alkyn‐1‐yl‐chloro(methyl)silanes: alkenes with chloro(methyl)silyl and diethylboryl groups in cis positions

The 1,1‐ethylboration of alkyn‐1‐yl‐chloro(methyl)silanes, Me₂Si(Cl)? C?C? R ( 1 ) and Me(H)Si(Cl)? C?C? R ( 2 ) [R = Bu ( 2a ), CH₂NMe₂ ( 2b )] requires harsh reaction conditions (up to 20 days in boiling triethylborane), and leads to alkenes in which the boryl and silyl groups occupy cis ((E)‐isomers: 3a , 3b , 5a , 5b ) or trans positions ((Z)‐isomers in smaller quantities: 4b and 6b ). The alkenes are destabilized in the presence of SiH(Cl) and CH₂NMe₂ units ( 5b , 6b ). NMR data indicate hyper‐coordinated silicon by intramolecular N? Si coordination in 3b and 5b , by which, at the same time, weak Si? Cl? B bridges are favoured. Copyright © 2005 John Wiley & Sons, Ltd.     

On the Effect of Tether Composition on cis/trans Selectivity in Intramolecular Diels–Alder Reactions

Intramolecular Diels–Alder (IMDA) transition structures (TSs) and energies have been computed at the B3LYP/6‐31+G(d) and CBS‐QB3 levels of theory for a series of 1,3,8‐nonatrienes, H₂C?CH? CH?CH? CH₂? X? Z? CH?CH₂ [? X? Z? =? CH₂? CH₂? ( 1 ); ? O? C(?O)? ( 2 ); ? CH₂? C(?O)? ( 3 ); ? O? CH₂? ( 4 ); ? NH? C(?O)? ( 5 ); ? S? C(?O)? ( 6 ); ? O? C(?S)? ( 7 ); ? NH? C(?S)? ( 8 ); ? S? C(?S)? ( 9 )]. For each system studied ( 1 – 9 ), cis‐ and trans‐TS isomers, corresponding, respectively, to endo‐ and exo‐positioning of the ? C? X? Z? tether with respect to the diene, have been located and their relative energies (E_rel^TS) employed to predict the cis/trans IMDA product ratio. Although the E_rel^TS values are modest (typically <3 kJ mol^?1), they follow a clear and systematic trend. Specifically, as the electronegativity of the tether group X is reduced (X?O→NH or S), the IMDA cis stereoselectivity diminishes. The predicted stereochemical reaction preferences are explained in terms of two opposing effects operating in the cis‐TS, namely (1) unfavorable torsional (eclipsing) strain about the C4? C5 bond, that is caused by the ? C? X? C(?Y)? group’s strong tendency to maintain local planarity; and (2) attractive electrostatic and secondary orbital interactions between the endo‐(thio)carbonyl group, C?Y, and the diene. The former interaction predominates when X is weakly electronegative (X?N, S), while the latter is dominant when X is more strongly electronegative (X?O), or a methylene group (X?CH₂) which increases tether flexibility. These predictions hold up to experimental scrutiny, with synthetic IMDA reactions of 1 , 2 , 3 , and 4 (published work) and 5 , 6 , and 8 (this work) delivering ratios close to those calculated. The reactions of thiolacrylate 5 and thioamide 8 represent the first examples of IMDA reactions with tethers of these types. Our results point to strategies for designing tethers, which lead to improved cis/trans‐selectivities in IMDAs that are normally only weakly selective. Experimental verification of the validity of this claim comes in the form of fumaramide 14 , which undergoes a more trans‐selective IMDA reaction than the corresponding ester tethered precursor 13 .     

Mono‐ and heterodi‐nuclear complexes of aluminium: synthesis,characterization and antifungal activity

Some new types of mononuclear derivatives, AlL(1–4)L(1–4)H ( 1a–1d ) of aluminium were synthesized by the reaction of Al(OPrⁱ)₃ and LH₂ [XC(NYOH)CHC(R)OH], X = CH₃, Y = (CH₂)₂, R = CH₃(L1H₂); X = C₆H₅, Y = (CH₂)₂, R = CH₃(L2H₂); X = CH₃, Y = (CH₂)₃, R = CH₃(L3H₂); X = C₆H₅, Y = (CH₂)₃, R = CH₃(L4H₂) in 1:2 molar ratio in refluxing benzene. Reactions of AlL(1–4)L(1–4)H with hexamethyldisilazane in 2:1 molar ratio yielded some new ligand bridged heterodinuclear derivatives AlL(1–4)L(1–4)SiMe₃ ( 2a – 2d ). All these newly synthesized derivatives were characterized by elemental analysis and molecular weight measurements. Tentative structures were proposed on the basis of IR and NMR spectra (¹H, ¹³C, 27 Al and ²⁹Si) and FAB‐mass studies. Schiff base ligands and their mono‐ and heterodi‐nuclear derivatives with aluminium have been screened for fungicidal activities. These compounds showed significant antifungal activity against Aspergillus niger and A. flavus. Copyright © 2007 John Wiley & Sons, Ltd.