257 research outputs found
Synthesis and structure of a tetrahydroxydisilane and a trihydroxycyclotrisiloxane with all the OH functions in cis position
No full textThe reaction of the tetrachlorodisilane R2Si2-Cl-4 (R = CH(SiMe3)(2)) with a mixture of H2O2/H2O/toluene resulted in the formation of the tetrahydroxy-disilane R2Si2(OH)(4). However the corresponding tetraaminodisilane R(2)S(i)2(NH2)(4) reacted under the same conditions to yield a trihydroxycyclotrisiloxane (RSi(OH)O)(3) (R = CH(SiMe3)(2)). The structures of both products were determined by X-ray crystallography. The latter structure is reminiscent of that of a calixarene with an inverse conic shape
ChemInform Abstract: Cyclopropyl Building Blocks in Organic Synthesis. Part 151. Diastereoselective Synthesis of Alkylcyclopropane‐Anellated Methyl 2‐Iminoimidazolinecarboxylates.
No full textTetra- and pentacyclopropyleyclopentadiene - Two new donor-substituted ligands for metal complexes
No full textSynthesis, structural characterization, and theoretical treatment of an unusual organozirconium hydroxide with the [Zr-6(mu(4)-O)(mu-O)(4)(mu-OH)(8)] core
No full textA novel organozirconium hydroxide, [(Cp Zr)(6)(mu(4)-O)(mu-O)(4)(mu-OH)(8)].2(C7H8) (2), was prepared by the hydrolysis of Cp ZrCl3. For the preparation of 2 the reagents KOH and water and the two-phase system ammonia/toluene were used. The crystal structure reveals that 2 is an octahedron comprising Cp Zr fragments arranged around an interstitial oxygen atom that preferentially occupies two off-center positions, 0.933(13) Angstrom apart from each other. The six Cp Zr fragments are bridged by a total of 12 mu-O and mu-OH groups. Molecular mechanical and ab initio calculations were carried out in order to analyze the stability and the bonding environment of the off-center structure by comparing to that with the ideal mu(6)-0 arrangement
ChemInform Abstract: N,N′-Bis(silyl)ethylenediamine and 1,3-Diaza-2-silacyclopentanes - Synthesis, Reactions, Crystal Structures.
No full textN,N '-bis(silyl)ethylenediamines and 1.3-diaza-2-silacyclopentanes - Synthesis, reactions, crystal structures
No full textEthylenediamine reacts with chlorosilanes to give N,N'-bis(silyl)ethylenediamines [(H2C-NHSiRR'R")2,3: R, R'=Me; R" = CMe3; 4: R = H; R', R" = CMe3; 5: R, R'=CMe3, R" = OH]. In the reaction of N,N,N'-tris(trimethylsilyl)ethylenediamine with SiF4 the difluoro-bis(1.1.4-tris(trimethylsilyl)ethylenediamino)silane (6) is obtained. The 1.3-diaza-2-silacyclopentanes R2Si[N(SiMe2R')CH2](2), 7 - 10 (7: R = Cl, R' = Ph; 8: R = Cl, R' = CMe3; 9: R = H, Cl, R' = CMe3; 10: R = Br, R' = CMe3) are isolated from the reactions of the corresponding bis(silyl)ethylenediamines and halosilanes in Et2O with NEt3 as HHa1 acceptor. Dilithium derivatives of N,N'-bis(silyl)ethylenediamines react with fluorosilanes with formation of the 1.3-diaza-2-silacyclopentanes, R2Si[N(SiMe2R')CH2](2) (11 - 13) (11: R = F, R'= Me; 12: R = F, R' = CMe3; 13: R = CHMe2, R' = Me). N-Fluoro-di(tert-butyl)silyl-N,N'-bis(trimethylsilyl)ethylenediamine (14) is formed in the reaction of lithiated bis(trimethylsilyl)ethylenediamine with F2Si(CMe3)(2). 8 reacts in a molar ratio 1:2 with NaNH2 or NaOMe with formation of 15 and 16, respectively . R2Si[N(SiMe2CMe3)CH2](2), 15: R = NH2; 16: R = OMe]. 1.3-Bis(tert-butyldimethylsilyl)-2-tert-butyldimethylsiloxy-2-fluoro-1.3-diaza-2-silacyclopentane is the product of the reaction of 12 with LiOSiMe2CMe3. The crystal structures of 6 and 13 have been determined
Mono-, di-, and trimetallic complexes of the nonalternating polycondensed pi-perimeter decacyclene, C36H18: Synthesis, structure, and spectroelectrochemistry of [{(eta(5)-Me4EtC5)Co}(2)(mu-eta(5):eta(4)-C36H18)]
No full textReaction of the half-sandwich complexes [(eta (5)-Me4RC5)M(eta (2):O-acac)] (M = Co, Ni; R = Me or Et) with di- and trianions of the polycondensed pi -hydrocarbon decacyclene results in formation of the first Co and Ni triple-decker complexes of this hydrocarbon. For the title compound NMR spectra as well as a crystal structure analysis reveal an antarafacial coordination of two {(eta (5)-Me4EtC5)Co] fragments at the central six-membered ring and one of the neighboring five-membered rings of decacyclene. The bridging pi -perimeter decacyclene displays a bowl-shaped topology. In the case of Ni, coordination of two {(eta (5)-Me5C5)Ni} fragments at the central six-membered ring of decacyclene is observed, based on the results of H-1 and C-13 NMR studies. This coordination mode is without precedent for nickel organometallic compounds reported so far. The cobalt complex shows a rich spectroelectrochemistry. Results of cyclic voltammetry and coupled ESR experiments reveal a strong interaction of both metal centers in the mixed-valent monocation of [{(eta (5)-Me4EtC5)-Co}(2)(mu-eta (5):eta (4)-C36H18)]. This categorizes the title compound into Robin Day class III
N,N '-bis(silyl)ethylenediamines and 1.3-diaza-2-silacyclopentanes - Synthesis, reactions, crystal structures
No full textEthylenediamine reacts with chlorosilanes to give N,N'-bis(silyl)ethylenediamines [(H2C-NHSiRR'R")2,3: R, R'=Me; R" = CMe3; 4: R = H; R', R" = CMe3; 5: R, R'=CMe3, R" = OH]. In the reaction of N,N,N'-tris(trimethylsilyl)ethylenediamine with SiF4 the difluoro-bis(1.1.4-tris(trimethylsilyl)ethylenediamino)silane (6) is obtained. The 1.3-diaza-2-silacyclopentanes R2Si[N(SiMe2R')CH2](2), 7 - 10 (7: R = Cl, R' = Ph; 8: R = Cl, R' = CMe3; 9: R = H, Cl, R' = CMe3; 10: R = Br, R' = CMe3) are isolated from the reactions of the corresponding bis(silyl)ethylenediamines and halosilanes in Et2O with NEt3 as HHa1 acceptor. Dilithium derivatives of N,N'-bis(silyl)ethylenediamines react with fluorosilanes with formation of the 1.3-diaza-2-silacyclopentanes, R2Si[N(SiMe2R')CH2](2) (11 - 13) (11: R = F, R'= Me; 12: R = F, R' = CMe3; 13: R = CHMe2, R' = Me). N-Fluoro-di(tert-butyl)silyl-N,N'-bis(trimethylsilyl)ethylenediamine (14) is formed in the reaction of lithiated bis(trimethylsilyl)ethylenediamine with F2Si(CMe3)(2). 8 reacts in a molar ratio 1:2 with NaNH2 or NaOMe with formation of 15 and 16, respectively . R2Si[N(SiMe2CMe3)CH2](2), 15: R = NH2; 16: R = OMe]. 1.3-Bis(tert-butyldimethylsilyl)-2-tert-butyldimethylsiloxy-2-fluoro-1.3-diaza-2-silacyclopentane is the product of the reaction of 12 with LiOSiMe2CMe3. The crystal structures of 6 and 13 have been determined
Diastereoselective Synthesis of Alkylcyclopropane‐Annelated Methyl 2‐Iminoimidazolidinecarboxylates
No full textCyclopropane- and alkylcyclopropane-annelated methyl imidazolidinecarboxylates 5 are formed from unsubstituted 1-H and from 2'-substituted methyl 2-chloro-2-cyclopropylideneacetates (1-R) and N,N',N ''-triarylguanidines (2) in a domino process consisting of a Michael addition and an immediately ensuing ring closure by intramolecular nucleophilic substitution in moderate to very good yields (30-95%, 8 examples). The products 5 with alkyl substituents on the spirocyclopropane moiety are formed diastereoselectively. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)Land Niedersachsen and BayerCrop-Science AG; BASF A
Synthesis and structural characterization of an unusual heptameric aluminum imide and the surface fluorination products of the Al7N7 and Al(4)C(4)N(4)cores
No full text=Reaction of RCN with an excess of AIH(3).NMe3 in boiling toluene proceeds with the evolution of trimethylamine and provides an unusual heptameric aluminum imide (RCH2NAlH)(7) (R = I-adamantyl) (1). Compound 1 is the second heptameric aluminum imide characterized by structural analysis. Compound I reacts with Me3SnF to yield a mixture of partially fluorinated products of average composition (RCH2NAl)(7)F2.26H4.74 (2). The molecular structures of I and 2 show that both have an asymmetric Al7N7 core. Within the core, each aluminum atom binds to three nitrogen atoms in such a way that a cage-like structure is formed. The size dependent influence of the ligands on the Al-N core formation is discussed. We also report on a tetrafluoro compound (t-BuNCH2AlF)4 (3) with terminal Al-F bonds. (C) 2004 Elsevier B.V. All rights reserved
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