Attempts to Synthesize a Thiirane,Selenirane, and Thiirene by Dealkylation of Chalcogeniranium and Thiirenium Salts

Thiiranium salts [Ad₂SR]⁺X⁻ ( 5 , 8 , 9 , 11 , 12 ; X⁻=Tf₂N⁻ (Tf=CF₃SO₂), SbCl₆⁻) and seleniranium salts [Ad₂SeR]⁺X⁻ ( 14 , 16 , 17 , 23 – 25 ; X⁻=Tf₂N⁻, BF₄⁻, CHB₁₁Cl₁₁⁻, SbCl₆⁻) are synthesized from strained alkene bis(adamantylidene) ( 1 ). The disulfides and the diselenides (Me₃SiCH₂CH₂E)₂ ( 4 , 13 ), (tBuMe₂SiCH₂CH₂E)₂ ( 7 , 22 ), and (NCCH₂CH₂E)₂ ( 10 , 15 ; E=S, Se) have been used. The thiirenium salts [tBu₂C₂SR]⁺X⁻ ( 34 ) and [Ad₂C₂SR]⁺X⁻ ( 35 , 36 ) are prepared from the bis-tert-butylacetylene ( 2 ) and bis-adamantyl-acetylene ( 3 ) with R=Me₃SiCH₂CH₂ and tBuMe₂SiCH₂CH₂. Attempts to cleave off the groups Me₃SiCH₂CH₂, tBuMe₂SiCH₂CH₂, and NCCH₂CH₂ resulted in thiiranes 27 , 30 . No selenirane Ad₂Se ( 33 ) is formed from seleniranium salts, instead cleavage to the alkene ( 1 ) and diselenide ( 13 , 15 ) occurs. The thiirenium salt [Ad₂C₂SCH₂CH₂SiMe₃]⁺Tf₂N⁻ ( 35 ) does not yield the thiirene Ad₂C₂S ( 37 ), the three-membered ring is cleaved, forming the alkyne ( 3 ) and disulfide ( 4 ). All compounds are characterized by ESI mass spectra, NMR spectra, and by quantum chemical calculations. Crystal structures of the salts 8 , 12 , 25 , 17 , 26 , 36 and the thiiranes 27 , 30 are presented.     

Carbon-13 and proton NMR parameters of neopentyl-and trimethylsilylmethyl-thallium(III) derivatives and the x-ray crystal structure of bis(trimethylsilylmethyl)chlorothallium(III)

Carbon-13 and proton NMR spectra have been determined for organothallium (III) derivatives of the types RTlX₂ and R₂ TlX (R  (CH₃)₃CCH₂ or (CH₃)₃SiCH₂; X  Cl, Br or O₂CCH(CH₃)₂). The dependence of coupling of ¹³C and ¹H to thallium on the number and nature of R groups is discussed in terms of the Fermi contact mechanism for spinspin coupling.The crystal structure of [(CH₃)₃SiCH₂]₂ TlCl has been determined. The compound crystallises in the monoclinic space group P2₁/n, with a 10.618, b 24.492, c 6.017 Å, β 99.76°. The molecule is dimeric with each four-coordinate thallium atom bonded unequally to two bridging chlorine atoms. The CTlC angle is 168°.     

Synthesis and properties of alkylvanadium(III) alkoxides

The reactions of R₃V · THF (R  C₆F₅, CH₂SiMe₃) with one t-BuOH equivalent result in formation of unstable R₂V(Ot-Bu)·THF, which disproportionates readily to V^IV and V^II compounds. The interaction of V(Ot-Bu)₃ with Me₃SiCH₂Li in diethyl ether is accompanied by formation of the at-complex [Me₃SiCH₂V(Ot-Bu)₃]^-Li⁺ which decomposes with formation of (Me₃SiCH₂)₂V(Ot-Bu)₂ and [V(Ot-Bu)₃]^-Li⁺. As a result of exchange reaction of V(Ot-Bu)₃ with one mole of RMgX, the complexes RV(Ot-Bu)₂·XMgOt-Bu (R  Me, X  Br, R  CH₂Ph, CH₂SiMe₃, C₆F₅, X  Cl) have been obtained. The insertion of carbon dioxide in vanadiumcarbon and vanadiumoxygen bonds has also been investigated.     

Synthese von Fluoro-λ5-monophosphazenen und Fluoro-1, 3-diaza-2λ5, 4λ5-diphosphetidinen mittels der Staudinger-Reaktion

Synthesis of Fluoro-λ⁵-monophosphazenes and Fluoro-1,3-diaza-2λ⁵,4λ⁵-diphosphetidines by Means of the Staudinger Reaction 35 Tetrafluoro- and 2 difluorodiaza-diphosphetidines as well as 4 difluoro- and 30 monofluoro-λ⁵-monophosphazenes were prepared by the Staudinger reaction between tervalent phosphorus fluorides, R_nPF_3?n (n = 1, 2; R = R₂N, (CH₂)₅N, O(CH₂)₄N, RO, (CH₂O)₂, alkyl, aryl) and phenylazides, X? C₆H₄N₃ (X = H, 4-CH₃, 4-Cl, 4-Br, 4-NO₂, 3-NO₂). PF₃ does not react with phenylazide The influence of substituents on the structure of the reaction products is discussed. Kinetic measurements allowed to determine the constants λ^P_I of the substituents (CH₂)₅N, O(CH₂)₄N and R(C₆H₅)N (R = CH₃, C₂H₅, n-C₄H₉).     

Synthesis of C-functionalized acetylacetone and its europium complex. Preparation and study of luminescence of europium-containing sol-gel films

New fuctionalized ligand 3-(3′-triethoxysilylpropylaminocarbonyl)pent-2-on-3-en-4-ol (EtO)₃SiCH₂·CH₂CH₂NHC(O)-C[C(O)CH₃][=C(OH)CH₃] (I) containing ketoenol and triethoxysilyl groups is synthesized from 3-triethoxysilylpropyl isocyanate (EtO)₃SiCH₂CH₂CH₂N=C=O and acetylacetone. The reaction is accompanied by the formation of 2-(3′-triethoxysilylpropylaminocarboxy)-pent-2-en-4-one (EtO)₃SiCH₂CH₂·CH₂NHC(O)-OC(CH₃)=CH-C(O)CH₃ (II), the product of addition of acetylacetone enol form to isocyanate group. The ratio of amide I and urethane II forms is 7:3. Europium(III) tris[3-(3′-triethoxysilylpropylaminocarbonyl) pent-2-on-3-en-4-olate] is prepared from I and Eu(i-OPr)₃. An alternative pathway consists in the reaction of europium tris(acetylacetonate) with 3-triethoxysilylpropyl isocyanate. Conditions of formation of transparent europium-containing sol-gel films were developed. Thermal stability and photoluminescence of the films were investigated.     

Bimetallic Rare Earth Alkyl Complexes Bearing Bridged Amidinate Ligands: Synthesis and Activity for L-Lactide Polymerization

Four novel bridged‐amidines H₂L {1,4‐R¹[C(=NR²)(NHR²)]₂ [R¹=C₆H₄, R²=2,6‐ⁱPr₂C₆H₃ (H₂L¹); R¹=C₆H₄, R²=2,6‐Me₂C₆H₃ (H₂L²); R¹=C₆H₁₀, R²=2,6‐ⁱPr₂C₆H₃ (H₂L³); R¹=C₆H₁₀, R²=2,6‐Me₂C₆H₃ (H₂L⁴)]} were synthesized in 65%–78% isolated yields by the condensation reaction of dicarboxylic acid with four equimolar amounts of amines in the presence of PPSE at 180°C. Alkane elimination reaction of Ln(CH₂SiMe₃)₃(THF)₂ (Ln=Y, Lu) with 0.5 equiv. of amidine in THF at room temperature afforded the corresponding bimetallic rare earth alkyl complexes (THF)(Me₃SiCH₂)₂LnL¹Ln(CH₂SiMe₃)₂(THF) [Ln=Y ( 1 ), Lu ( 2 )], (THF)(Me₃SiCH₂)₂LnL²Ln‐ (CH₂SiMe₃)₂(THF) [Ln=Y ( 3 ), Lu ( 4 )], (THF)(Me₃SiCH₂)₂YL³Y(CH₂SiMe₃)₂(THF) ( 5 ), (THF)(Me₃SiCH₂)₂YL⁴‐ Y(CH₂SiMe₃)₂(THF) ( 6 ) in 72% –80% isolated yields. These neutral complexes showed activity towards L‐lactide polymerization in toluene at 70°C to give high molecular weight (M>10⁴) and narrow molecular weight distribution (M_w/M_n≦1.40) polymers     

Preparation and reactivity of the new cyclopentadienyl-bridged complex (Me2SiCH2CH2SiMe2)(C5H4Fe(CO)2)2

A new metal-metal bonded binuclear iron system [Me₂SiCH₂CH₂SiMe₂][η⁵-C₅H₄Fe(CO)₂]₂ (2) has been prepared by treating two equivalents of NaCp with one equivalent of ClSi(Me)₂CH₂CH₂SiClMe₂ obtaining the intermediate (C₅H₅)Si(Me)₂CH₂CH₂Si(Me)₂(C₅H₅) which then is directly allowed to react with Fe(CO)₅ given 2 in 30% yield. From this cyclopentadienyldisilyl linked system three new binuclear irom complexes are formed. Treatment of 2 with Na/Hg in THF produced the dianion [Me₂SiCH₂CH₂SiMe₂][η⁵-C₅H₄Fe(CO)₂^?]₂ which is quenched with CH₃I giving [Me₂SiCH₂CH₂SiMe₂][η⁵-C₄H₄Fe(CO)₂CH₃]₂ (4) in 76% yield. Complex 2 is oxidized with 1.2 equivalent of I₂ to give [Me₂SiCH₂CH₂SiMe₂][η⁵-C₅H₄Fe(CO)₂I]₂ (5) in 85% yield. Photolysis of 5 (1 equiv.) and PPh₃ (3 equiv.) results in the formation of the bis-substituted compound [Me₂SiCH₂CH₂SiMe₂][η⁵-C₅H₄Fe(CO)(PPh₃)I]₂ (6). These four new binuclear iron complexes are characterized by ¹H, ¹³C, and ³¹P NMR and IR spectroscopy.     

Molecular design and photo-physics of quaternary hybrid terbium centered systems with novel functional di-urea linkages of strong chemical bonds through hydrogen transfer addition

Two kinds of crosslinking reagents, 3-aminopropyl-methyl-diethoxylsiliane (H₂N(CH₂)₃SiCH₃(OC₂H₅)₂, abbreviated as APMES) and N-2-aminoethyl-3-aminopropyltriethoxylsiliane (H₂N(CH₂)₂HN(CH₂)₃Si(OC₂H₅)₃, abbreviated as AEAPES) are modified by 3-(triethoxysilyl)-propyl isocyanate (TESPIC) to afford two novel crosslinking molecular derivatives as bridge ligands. Then the ternary organic-inorganic molecular-based hybrid system with these functional bridge ligands and 1,10-phenanthroline (phen) are constructed with the two components equipped with covalent bonds. The two components of APMES (or AEAPES) and TESPIC is linked through -NHC(O)NH- groups which is applied to coordinate to Tb³⁺ and further formed Si-O backbones after co-hydrolysis and co-polycondensation processes, while phen behaves as the main energy donor for the sensitization of luminescence of Tb³⁺. Luminescence spectra were utilized to characterize the photo-physical properties of the obtained hybrid system and the above spectroscopic data reveal that the phen in this favorable hybrid system behaves the main energy donor for the luminescence of Tb³⁺. In this way, the intra-molecular energy transfer process took place within these molecular-based hybrids and strong green and blue emissions of Tb³⁺ have been achieved.     

NMR study (1H, 13C and 29Si) of the methylallylsilanes

¹H, ¹³C and ²⁹Si NMR data for the compounds (CH₃)_xSi(CH₂CHCH₂)_4-x are reported. The ¹H resonances from the π system are indicative of the electron-supplying inductive effect (+I) of the (CH₃SiCH₂, moiety but the corresponding ¹³C_π chemical shifts seem to be influenced by a sterically induced polarization of the C-H bonds. The ¹³C_All, ¹³C_Me and ²⁹Si chemical shift data reveal an important neighbour anisotropy contribution originating from the π system. Ultraviolet study of the compounds mentioned above gives indication of a σ—π conjugation in accordance with PES and ab initio results [1—5]. The trend observed in the various coupling constants is too small to be Interpreted.     

Stabilization in the order I>Br>Cl among trimethylsilylmethyl halides,compared to carbon analogs. Possible role of electronegativity in organosilicon chemistry

Electronegativities may be used to rationalize the observation that the equilibrium, CH₃(CH₂)₃I + (CH₃)₃SiCH₂Cl ? CH₃(CH₂)₃Cl + (CH₃)₃SiCH₂I, lies to the right.     

Radicals containing β-muonium and α or β substituents:

A range of radicals, CH₂(Mu) HX (1) and XCH(Mu)CR₂ (2), where X is a second-row substituent, have been studied by transverse-fieldμ ⁺SR spectroscopy. The reduced muon—electron hyperfine coupling constants (A′_Mu) for class (1) were all close to 37.3 G, the value for the parent radical CH₂(Mu)CH₂. However, for class (2)A′ _Mu values are greatly reduced, as is the case for the corresponding hydrogen derivatives, XCH₂CR₂, relative to CH₃CH₂. Nevertheless, the reduction in coupling for Mu in (2] is appreciably less that that for¹H in XCH₂CR₂ radicals, suggesting significant competition between Mu and X for the out-of-plane site. In addition to theμ ⁺ SR studies, the ESR spectra for the radicals (MeO)₃SiCHCH₃ and (MeO)₃SiCH₂CH₂ have been measured for comparative purposes.     

Beiträge zur Chemie des Bors, 134. Addukte von (Dimethylamino)boranen mit Aluminum- und Galliumhalogeniden

Contributions to the Chemistry of Boron, 134. Adducts of (Dimethylamino)boranes with Aluminium and Gallium Halides²⁾ The (dimethylamino)boranes (CH₃)₂BN(CH₃)₂ ( 1 ) and RB[N(CH₃)₂]₂ ( 2, 3 ) form 1 : 1 adducts 1a – c and 2a , b , 3a , b with AlCl₃, AlBr₃, and GaCl₃, respectively, in contrast to B[N(CH₃)₂]₃ ( 4 ) which reacts with GaCl₃ to produce a 1:2 adduct 4a . NMR and IR data are in accord with the presence of a simple N – Al or N – Ga coordinative bound for the first two classes of compounds. However, 4a is to be regarded as a tris(dimethylamino)borane-dichlorogallium(1+) tetrachlorogallate containing a bidentate aminoborane component.     

Synthetic,spectral, thermal and antimicrobial studies on some bis(N,N′‐dialkyldithiocarbamato) antimony(III) alkylenedithiophosphates

Bis(N, N′‐dialkyldithiocarbamato)antimony(III) alkylenedithiophosphates of the type [R₂NCS₂]₂ SbS(S)POGO [where NR₂ = N(CH₃)₂, N(C₂H₅)₂ and N(CH₂)₄; G = ? CH₂? C(C₂H₅)₂? CH₂? , ? CH₂? C(CH₃)₂? CH₂? , ? CH(CH₃)? CH(CH₃)? and ? C(CH₃)₂? C(CH₃)₂? ] were synthesized and characterized by physico‐chemical, spectral [UV, IR and NMR (¹H, ¹³C and ³¹P)] and thermal (TG, DTA and DSC) analysis. The TG decomposition analysis step of the complex indicated the formation of Sb₂S₃ as the final product. The first endothermic peak in DSC indicated the melting point of the complexes. These complexes were screened for their antimicrobial activities using the disk diffusion method. All the complexes showed good activity as antibacterial and antifungal agents on some selected bacterial and fungal strains, which increased on increasing the concentration. Chloroamphenicol and terbinafin were used as standards for comparison. Copyright © 2007 John Wiley & Sons, Ltd.     

Base Catalysed Racemization of Ethylenediamine-N,N,N′-triacetato-aqua-cobalt(III)

The kinetics of the base catalysed racemization of [Co(EN3A)H₂O]

1 Abbreviations: EN3A^3?=(^?OOCCH₂)₂N(CH₂)₂NHCH₂COO^?; ME3A^3?=(^?OOCCH₂)₂N(CH₂)₂ N(CH₃)CH₂COO^?; EDDA^2?=^?OOCCH₂NH(CH₂)₂NHCH₂COO^?; EDTA^4?=(^?OOCCH₂)₂N(CH₂)₂N(CH₂COO^?)₂;TNTA^4?=(^?OOCCH₂)₂N(CH₂)₃N(CH₃COO^?)₂; HETA^3?=(^?OOCCH₂)₂N(CH₂)₂N(CH₂COO^?)CH₂CH₂OH; en=H₂N(CH₂)₂NH₂; Meen=H₂N(CH₂)₂NHCH₃; sar^?=^?OOCCH₂NHCH₃.

were studied polarimetrically in aqueous buffer solution. The reaction rate is first order in OH^? and in complex, in weakly acidic medium. Activation parameters are ΔH≠=22 kcal · mol^?1, ΔS≠=26 cal · K^?1. The results are discussed in terms of an S_N1CB mechanism involving exchange of the ligand water molecule. The N-methylated analogue [Co(ME3A)H₂O] does not racemize in the pH-range investigated. Loss of optical activity occurs at a rate which is about 1,000 times slower than the racemization of [Co(EN3A)H₂O](60°) and coincides with the decomposition of the complex.     

Synthesis and structures of new 1,3,6,2-dioxazaborocanes containing substituents in the ocane fragment

New 1,3,6,2-dioxazaborocanes R¹N(CHR³CR⁴R²O)(CHR⁶CHR⁵O)BX (1–11, X = Ph, 4-MeC₆H₄, Me; R¹ = Me, PhCH₂; R², R³, R⁴, R⁵, R⁶ = H, Ph) were synthesized by the reactions of aryl- or methylboronic acids with dialkanolamines. The treatment of (Me₂NCH₂CH₂O)₃B (15) with MeN(CH₂CH₂OH)(CH₂CPh₂OH) afforded 2-[2-(dime-thylamino)ethoxy]-1,3,6,2-dioxazaborocane (12). 2-Fluoro-1,3,6,2-dioxazaborocanes R¹N(CHR³CHR²O)(CH₂CH₂O)BF (13: R¹ = PhCH₂, R² = R³ = H; 14: R¹ = Me, R² = R³ = Ph, threo) were synthesized by the reaction of bis(trimethylsilyl) ethers of the corresponding dialkanolamines with BF₃·Et₂O. The new borocanes can be used for the synthesis of the corre-sponding germanium derivatives PhCH₂N(CH₂CH₂O)₂GeX₂ (16, X = OEt; 17, X = Cl), as exemplified by the reaction of compound 6. The structures of erythro-MeN(CH₂CH₂O)(CHPhCHPhO)BPh (3), threo-MeN(CH₂CH₂O)(CHPhCHPhO)BPh (4), erythro-MeN(CH₂CH₂O)(CHPhCHPhO)B(4-MeC₆H₄) (8), and PhCH₂N(CH₂CH₂O)₂BF (13) were established by X-ray diffraction. The coordination polyhedra of the boron atoms in these complexes can be described as distorted tetrahedra. The boron-nitrogen distances (1.705(7)–1.723(3) Å) provide unambiguous evidence for the presence of the B←N transannular interaction in these compounds. The structures of the resulting borocanes containing phenyl substituents at the carbon atoms of the ocane skeleton were studied by NMR spectroscopy and quantum chemical density functional theory calculations.     

Metalmetal bonded triazenido compounds : II. Compounds with M = RhI,IrI; R = Me,aryld and X = Cl,Br, I Cl,Br, I

Complexes

(M = Rh, X = Cl, M = Ir, X = Cl, Br, I and R = CH₃, R′ = CH₃, p-tolyl) have been made by the reaction of (Ph₃P)₂(CO)MX with

. The proposed structure is analogous to that of the related copper derivatives and contains a five-membered ring in which an M^I to Ag^I donor bond is bridged by an azenido group, while the halide atom X has migrated from M^I to Ag^I.Carbon monoxide at 1 atm reacts rapidly and quantitatively with the iridium compounds to give novel acyltriazenido compounds {Ph₃P(CO)₂ - Ir[OCN(R)N=NR′]} (R = CH₃, p-tolyl; R′ = CH₃, p-tolyl).     

Trioxaphosphocanes-1,3,6,2, etude par R.M.N. (13C, 1H, 31P et stereochimie

The stereochemistry of several 2-R-1,3,6,2-trioxaphosphocanes (R = Cl, OCH₃, CH₃, N(CH₃)₃ has been investigated by ¹H, ¹³C and ³¹P n m r spectroscopy.     

Metastable ion study of organosilicon compounds. Part V—tetramethoxysilane and trimethoxymethylsilane

The fragmentations of tetramethoxysilane ((CH₃O)₄Si (1)) and trimethoxymethylsilane ((CH₃O)₃SiCH₃ (3)) induced by electron impact were investigated by mass-analysed ion kinetic energy (MIKE) spectrometry and a deuterium-labelling study. These molecular ions begin to fragment by the loss of CH₃ or CH₃O. These fragmentations are followed by the loss of an aldehyde molecule (H₂CO), as commonly observed in the mass spectra of alkoxysilanes. Almost complete scrambling of the methoxy hydrogens takes place in the metastable molecular ion, [1]⁺˙, prior to the decomposition. On the other hand, a moderate extent of scrambling of the hydrogens takes place in [3]⁺˙. The fragmentations of [1]⁺˙ and [3]⁺˙ were compared with those of the corresponding carbon analogues, tetramethoxymethane ((CH₃O)₄C (2)) and 1,1,1-trimethoxyethane ((CH₃O)₃CCH₃ (4)), respectively.     

Assembly and Dissociation of Α-Cyclodextrin [2]Pseudorotaxanes with α,ω-Bis(N-(N,N′-dimethylethylenediamine)alkane Threads

A series of novel bischelate bridging ligands, CH₃NH(CH₂)₂N(CH₃)(CH₂)_nN(CH₃)(CH₂)₂NHCH₃ (n = 9, 10, 11, and 12) were synthesized as hydrochloride salts and characterized by elemental analyses, electrospray mass spectrometry, and ¹H and ¹³C NMR spectroscopy. These ligands form [2]pseudorotaxanes with α-cyclodextrin (α-CD) and the stability constants have been determined from ¹H NMR titrations in D₂O. The kinetics and mechanism of the assembly and dissociation of a [2]pseudorotaxane in which α-CD has been threaded by the CH₃NH₂(CH₂)₂N(CH₃)(CH₂)₁₂N(CH₃)(CH₂)₂NH₂CH₃²⁺ ligand were determined in aqueous solution using ¹H NMR spectroscopy. A weak inclusion of the dimethylethylenediamine end group precedes the passage of the α-CD onto the hydrophobic dodecamethylene chain.     

N-Monobromamide: Darstellung durch Bromierung mit „Dibromisocyanursäure”, Eigenschaften

By reaction of primary carboxamides with “dibromoisocyanuric acid” (DBI) N-monobromoamides can be readily obtained as well as the N,N-dibromoamides described in an earlier paper¹. Reactions, some of them new, and properties of these compounds are described and compared with those of the N,N-dibromoamides. Like other compounds bearing the NHBr group^{2, 3} the N-monobromocarboxamides disproportionate at room temperature according to: 2 RCONHBr ? ? RCONH₂+RCONBr₂. For CH₃CONHBr the equilibrium constant was found to beK=0.02. In aqueous solution they behave as weak acids. The dissociation constants of eight compounds [R=?CH₃, ?C₂H₅, ?CH₂Cl, ?CHCl₂, ?CCl₃, ?CF₃, ?C(CH₃)₃ and ?C₆H₅] were measured: they differ from those of the corresponding carboxylic acids by about three powers of ten.