bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computation of the Laplace inverse transform by application of the wavelet theory
Authors: Wang Jizeng , Zhou Youhe , Gao Huajian 
Published: December 2003

AbstractAn efficient and robust method of solving Laplace inverse ransform is proposed based on the wavelet theory. The inverse function is expressed as a wavelet expansion with rapid convergence. Several examples are provided to demonstrate the methodology. As an example of application, the proposed inversion method is applied to the dynamic analysis of a single‐degree‐of‐freedom spring–mass–damper system whose damping is described by a stress–strain relation containing fractional derivatives. The results are compared with previous studies. Copyright © 2003 John Wiley Sons, Ltd
Numerical homogenization of active material finite‐element cells
Authors: Buehler Markus J. , Bettig Bernhard P. , Parker Gordon G. 
Published: December 2003

AbstractWe present the homogenization of a parametrically defined periodic microstructure in which it is possible to separately control the volume fractions of conventional material, active material and void. The effective material properties from the homogenization reduce the necessary finite‐element model complexity and also allow for topology optimization of smart structures or optimization of the microstructure itself. Homogenization equations for piezoelectric material including thermal effects are derived with a first‐order asymptotic approach. The homogenization problem is solved numerically for discrete values of the design parameters. An interpolation technique is used to find analytical, continuously derivable functions for material properties of the design parameters. Consideration is given to planar microstructures and the treatment of microstructures consisting of dielectrically distinct materials. Copyright © 2003 John Wiley & Sons, Ltd.
Security Maintenance Mediation: a technology for preventing unintended security breaches
Authors: King Roger (Buzz) 
Published: December 2003

AbstractWeb‐resident information is becoming ‘smarter’, in the sense that emerging technology will support the annotation of it with ontological terms, which will be used to locate and reuse information. This will pose a great security risk in the form of unintended breaches (as distinct from deliberate invasions). Web‐resident information will be far more readily available and relevant, thus causing inadvertent releases of secure information to potentially cause it to be diffusely spread across the Internet. Then as this information is iteratively transformed and integrated with other information, it will become irretrievable and potentially used in a myriad of unpredictable ways. The problem is that ontological annotations, while making information more understandable in its original form, do not provide a means for easily capturing the complex semantics of information that has been transformed via abstraction, aggregation, and integration. This demands the development of a semantically rich way of specifying ‘views’ of Web information, to which security controls can be attached. Also needed is a way for users of secure information to easily and voluntarily blend—and thereby propagate—security controls as information is transformed. Information mediators designed by collaborative teams of experts are proposed as the vehicle for wrapping information, so that at each step of reuse, high‐level views and their corresponding integrity controls can be made easily accessible to trusted users who will then be able to ensure their proper maintenance. Copyright © 2004 John Wiley & Sons, Ltd.
Parallel operation of CartaBlanca on shared and distributed memory computers
Authors: Padial‐Collins N. T. , VanderHeyden W. B. , Zhang D. Z. , Dendy E. D. , Livescu D. 
Published: December 2003

AbstractWe describe the parallel performance of the pure Java CartaBlanca code on heat transfer and multiphase fluid flow problems. CartaBlanca is designed for parallel computations on partitioned unstructured meshes. It uses Java's thread facility to manage computations on each of the mesh partitions. Inter‐partition communications are handled by two compact objects for node‐by‐node communication along partition boundaries and for global reduction calculations across the entire mesh. For distributed calculations, the JavaParty package from the University of Karlsruhe is demonstrated to work with CartaBlanca. Copyright © 2004 John Wiley & Sons, Ltd.
Investigation of the Crystallization Stages of LTA‐Type Zeolite by Complementary Characterization Techniques
Authors: Smaihi Monique , Barida Olivier , Valtchev Valentin 
Published: December 2003

AbstractThis paper reports on the physicochemical reorganizations, at 40 °C, of a template‐free aluminosilicate system yielding an LTA‐type zeolite. The events that take place in the system during the transformations of the amorphous material into a crystalline material were monitored by various characterization techniques which provide information from the molecular to the micrometer scale. High‐resolution solid‐state 29Si and 27Al MAS NMR spectroscopy, small‐angle X‐ray scattering (SAXS), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) were used in order to achieve a better understanding of the structural properties of the precursor gel and its transformation into a crystalline zeolite‐type material. The experimental results show that the first crystallization stage proceeds by reorganization of the amorphous aluminosilicate units formed during the mixing of the precursors. This reorganization involves an ordering of the Si−O−Al bond angles and operates on aggregates of constant volume. The crystallization process takes place in the volume of the aggregates by propagation through the gel phase. This propagation through the gel continues to complete the transformation of the particles into crystalline zeolite Na‐A nanocrystals with a rough surface. After this stage, the growth in the system is dominated by the solution‐mediated transport, which leads to the formation of well‐shaped zeolite A crystals. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Thermal Stability and Absorption Spectroscopic Behavior of (μ‐Peroxo)dicopper Complexes Regulated with Intramolecular Hydrogen Bonding Interactions
Authors: Yamaguchi Syuhei , Wada Akira , Funahashi Yasuhiro , Nagatomo Shigenori , Kitagawa Teizo , Jitsukawa Koichiro , Masuda Hideki 
Published: December 2003

AbstractIn order to clarify the effect of hydrogen bonding on the stabilities of (μ‐peroxo)dicopper complexes with a trans‐μ‐1,2‐peroxo form, novel copper complexes with intramolecular hydrogen bonding interaction sites have been synthesized, and their spectroscopic properties and thermal stabilities studied. The selected tripodal tetradentate ligands were tris(2‐pyridylmethyl)amine (TPA) derivatives bearing pivalamido and amino groups at the 6‐position of the pyridine ring in TPA, {[6‐(pivalamido)pyrid‐2‐yl]methyl}bis(pyrid‐2‐ylmethyl)amine (MPPA) and [(6‐aminopyrid‐2‐yl)methyl]bis(pyrid‐2‐ylmethyl)amine (MAPA). The single‐crystal X‐ray structure of a monomeric CuII complex with N3− namely [Cu(mppa)N3]ClO4 (1a), revealed an interligand hydrogen bonding interaction between the substituent NH group of MPPA and the azide nitrogen atom in the axial position. The CuI complexes of MPPA and MAPA were immediately oxygenated with dioxygen in acetone solution at −78 °C to give the μ‐peroxo dinuclear copper(II) complexes [{Cu(mppa)}2(O2)]2+ (1b) and [{Cu(mapa)}2(O2)]2+ (2b). These complexes exhibited two kinds of characteristic absorption bands (π*σ⇄dσ, π*v⇄dσ) originating from the ligand−metal charge transfer (LMCT) of O22− to Cu. Affected by the hydrogen bonding interaction, the π*σ⇄dσ CT band shifted significantly to a higher energy region and the π*v⇄dσ CT absorbance decreased due to stabilization of the π*σ orbital and restriction of the Cu−O bond rotation. The thermal stabilities of the (μ‐peroxo)dicopper(II) complexes were estimated from their decomposition rates which decreased in the order, 2b ≈︁ [{Cu(tpa)}2(O2)]2+ (3b) > 1b >> [{Cu(6‐metpa)}2(O2)]2+ (4b) {6‐MeTPA = [(6‐methylpyrid‐2‐yl)methyl]bis(pyrid‐2‐ylmethyl)amine}. The above findings indicate that the interligand hydrogen bonding interaction, although overcome to some extent by the adverse effect of the steric bulk of the NH group, is inclined to stabilize (μ‐peroxo)dicopper(II) complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Reaction of MnII Iodides Bearing the β‐Diketiminate Ligand: the First Divalent Manganese N‐Heterocyclic Carbene Complexes [{HC(CMeNAr)2}MnI{C[N(iPr)CMe]2}] and [{HC(CMeNAr)2}MnNHAr{C[N(iPr)CMe]2}] (Ar = 2,6‐iPr2C6H3)
Authors: Chai Jianfang , Zhu Hongping , Most Kerstin , Roesky Herbert W. , Vidovic Denis , Schmidt Hans‐Georg , Noltemeyer Mathias 
Published: December 2003

AbstractThe manganese mono‐iodide [HC(CMeNAr)2]MnI(THF) (Ar = 2,6‐iPr2C6H3) (3) was prepared in good yield from the reaction of [HC(CMeNAr)2]K with MnI2 in THF. Treatment of 3 under reflux in toluene and removing all the volatiles in vacuo afforded the dimeric compound [{HC(CMeNAr)2}Mn]2(μ‐I)2 (4). Displacement of the coordinated THF in 3 by a strong Lewis base C[N(iPr)CMe]2 or by adding C[N(iPr)CMe]2 to the toluene solution of 4 readily gave the N‐heterocyclic carbene adduct [{HC(CMeNAr)2}]MnI{C[N(iPr)CMe]2} (5). Reduction of 5 with sodium/potassium alloy at room temperature unexpectedly resulted in the formation of the monomeric compound [{HC(CMeNAr)2}]MnNHAr{C[N(iPr)CMe]2} (6). Alternatively 6 was obtained by the salt elimination reaction of 5 with LiNHAr. Compounds 5 and 6 are the first examples of divalent manganese N‐heterocyclic carbene adducts and the first manganese non‐carbonyl carbene complexes. The single crystal X‐ray structural analyses reveal that compounds 3 and 6 are monomeric and compound 4 is dimeric in the solid state. The manganese centers in these compounds exhibit a distorted tetrahedral geometry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
η1‐Vinylidene to η2‐Alkyne Isomerization of Tungsten and Molybdenum Complexes
Authors: Ipaktschi Junes , Mohsseni‐Ala Javad , Uhlig Sascha 
Published: December 2003

AbstractThe thermal isomerizations of η1‐vinylidene complexes [(η5‐C5H5)(CO)(NO)W=C=CHR] [5a, R = Si(CH3)2C(CH3)3; 5c, R = C(CH3)3] as well as [(η5‐C5H5)(CO)(NO)Mo=C=CHC(CH3)3] (8), to the corresponding η2‐1‐alkyne complexes [(η5‐C5H5)(CO)(NO)W(η2‐H−C≡C−R)] [7a, R = Si(CH3)2C(CH3)3; 7c, R = C(CH3)3] and [(η5‐C5H5)(CO)(NO)Mo{η2‐H−C≡C−CHC(CH3)3}] (9) has been investigated. Activation parameters for the isomerization of 5a in [D6]benzene and 8 in [D8]toluene and [D5]ethanol were determined. In [D8]toluene η1‐vinylidene complex 5a undergoes a single step 1,2‐shift of the silyl group from Cβ to Cα. However, complex 8 shows dichotomous behavior. The isomerization 8 ⇄ 9, dependent upon the solvent applied, occurs by means of two different pathways: in a nonpolar solvent, 8 tautomerizes via the 1,2‐migration of the hydrogen atom to 9 and in ethanol this tautomerization proceeds by a multi‐step process via deprotonation‐protonation and subsequent reductive elimination. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Structure, and Biological Activity of New Azine‐Bridged Dinuclear Platinum(II) Complexes − a New Class of Anticancer Compounds
Authors: Kalayda Ganna V. , Komeda Seiji , Ikeda Kyoko , Sato Takaji , Chikuma Masahiko , Reedijk Jan 
Published: December 2003

AbstractA recently described new class of dinuclear platinum anticancer compounds, represented so far by the isomeric azine‐bridged complexes [{cis‐Pt(NH3)2Cl}2(µ‐pzn)]Cl2 (1) (pzn = pyrazine), [{cis‐Pt(NH3)2Cl}2(µ‐pmn)]Cl2 (2) (pmn = pyrimidine) and [{cis‐Pt(NH3)2Cl}2(µ‐pdn)](NO3)2 (3) (pdn = pyridazine), has been added to. Three new dinuclear complexes of this type, [{cis‐Pt(NH3)2Cl}2(µ‐2,5pzn)]Cl2 (4) (2,5pzn = 2,5‐dimethylpyrazine), [{cis‐Pt(NH3)2Cl}2(µ‐qzn)]Cl2 (5) (qzn = quinazoline), and [{cis‐Pt(NH3)2Cl}2(µ‐pht)](NO3)2 (6) (pht = phthalazine), have been newly synthesized and characterized by 1H and 195Pt NMR spectroscopy. The interaction of the new compounds with 2 equiv. of 9EtG in D2O at 310 K has been investigated. Complexes 4 and 5 undergo substitution of both chloride ligands by 9EtG similarly to the related complexes 1 and 2, respectively. The methyl substituents on the pyrazine ring induce steric hindrance in 4 resulting in a slower reaction rate as compared to 1. Similarly to the case of 3, interaction of complex 6 with 9EtG results in cleavage of the Pt−N(pht) bond and subsequent formation of the polymeric species. A cytotoxicity assay of 4−6 has been performed on seven human tumor cell lines and on L1210 murine leukemia cell lines, sensitive and resistant to cisplatin. Compounds 4 and 5 exhibit lower cytotoxicity than the analogous complexes with unsubstituted azines. Complex 6 is more active: its cytotoxicity in the L1210 cell lines is similar to that of cisplatin. Analysis of nuclear DNA fragmentation in L1210 cells treated with the azine‐bridged complexes 1−6 has been carried out. The results clearly indicate induction of apoptosis by all the compounds, implying considerable anticancer potential. The structure‐activity relationship for this class of dinuclear platinum(II) complexes is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Non‐Oxo Vanadium(IV) Complexes of Aminebis(phenolate) [O,N,O] Donor Ligands and Solution Studies of Isostructural VIV and MnIV Complexes
Authors: Paine Tapan K. , Weyhermüller Thomas , Bill Eckhard , Bothe Eberhard , Chaudhuri Phalguni 
Published: December 2003

AbstractMononuclear non‐oxo vanadium(IV) complexes, [VIVLMe2] (1) and [VIVLtBu2] (2), with a tridentate bis(phenol) ligand H2L bearing the O2N donor atoms and with either dimethyl or di‐tert‐butyl substituents have been synthesized and the X‐ray structures of 1 and 2 are reported. Additionally, 3, an MnIV complex [MnIVLMe2], and 4, the anion containing the MnIII center [MnIIILMe2]−, are discussed. The X‐ray structure of 4 present as an anion in 4a, [(Me3tacn)2MnII2(μ‐OOCCH3)3][MnIIILMe2], where Me3tacn = 1,4,7‐trimethyl‐1,4,7‐triazacyclononane, confirms the magnetic susceptibility results of the high‐spin d4 nature of the manganese center in 4. The compounds were characterized by elemental analysis, IR, UV/Vis, mass spectrometry, EPR spectroscopy, electrochemical and variable‐temperature (2−295 K) magnetic susceptibility measurements. The electrochemical results of 1 and 2 suggest the metal‐centered oxidation, i.e. the generation of a VV−phenolate species, prior to the second oxidation attributable to the formation of a VV−phenoxyl radical species. Isomerization of the meridional form for the bis(ligand)metal species to the facial form has been observed for 1 and 3 in solution. The EPR spectroscopic data of 1 and 2 clearly show a considerable increase in the in‐plane π bonding, as is expected for a phenolate ligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
High Molecular Weight Phosphazene Copolymers Having Chemical Functions Inside Chiral Pockets Formed by (R)‐(1,1′‐Binaphthyl‐2,2′‐dioxy)phosphazene Units
Authors: Carriedo Gabino A. , García Alonso Francisco J. , Presa‐Soto Alejandro 
Published: December 2003

AbstractThe polyphosphazene {[NPCl2]x[NP(O2C20H12)]1−x}n (O2C20H12 = 1,1′‐binaphthyl‐2,2′‐dioxy) reacted in refluxing THF in the presence of Cs2CO3 with HOC5H4N or para‐substituted phenols HOC6H4R to give the random copolymers {[NP(OC5H4N)2]x[NP(O2C20H12)]1−x}n (1) or {[NP(OC6H4R)2]x[NP(O2C20H12)]1−x}n [R = CN (2), COMe (3), CO2nPr (4), PPh2 (5)] and with H2NnBu to give {[NP(NHnBu)2]x[NP(O2C20H12)]1−x}n (6). The reaction of the polymer {[NPCl2]x[NP(O2C20H10Br2)]1−x}n (O2C20H10Br2 = 6,6′‐dibromo‐1,1′‐binaphthyl‐2,2′‐dioxy) with HOC6H4PPh2 and Cs2CO3 gave {[NP(OC6H4PPh2)2]x[NP(O2C20H10Br2)]1−x}n (7). Those polymers have a very high glass‐transition temperature (Tg) and a chemical function or ligand that is in the interior of a chiral pocket. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
New Diphosphane Ligands Based on Bisphenol A Backbones − Synthesis and Coordination Chemistry
Authors: van der Vlugt Jarl Ivar , Grutters Michiel M. P. , Mills Allison M. , Kooijman Huub , Spek Anthony L. , Vogt Dieter 
Published: December 2003

AbstractA series of easily accessible diphosphane compounds 1−4, based on bisphenol A derived backbones, has been prepared. A straightforward two‐step synthetic route has been employed to obtain these new ligands in good yields from cheap starting materials. Molecular structures for both compound 2 and its oxidized form (5·H2O) have been determined and are discussed in detail. The coordination of ligand 2 to palladium, platinum, and rhodium precursors has been studied by NMR spectroscopy as well as X‐ray crystallography. The molecular structures of the face‐to‐face dimeric species [{PdCl(CH3)(2)}2] (6), [{PtCl2(2)}2] (7), and [{RhCl(CO)(2)}2] (8) are described in detail. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The First Chemical Achievements and Publications by Justus von Liebig (1803−1873) on Metal Fulminates and Some Further Developments in Metal Fulminates and Related Areas of Chemistry
Authors: Beck Wolfgang 
Published: December 2003

AbstractThe first chemical investigations and publications by Justus von Liebig dealt with the fulminates of silver and mercury. Even as a boy Liebig had learnt how to prepare silver fulminate, and as student of chemistry in Erlangen (1821) he studied the properties and reactions of silver fulminate. In Paris in 1823 (together with Gay‐Lussac) he succeeded in analyzing quantitatively the highly explosive silver compound. This great experimental success with the dangerous silver fulminate was most important in three respects: i. The development of the experimental method later culminated in Liebig’s perfected and well‐known C,H,N analysis of organic compounds (1830). ii. It led to the concept of isomerism when F. Wöhler found that silver cyanate had the same composition as silver fulminate. iii. It was decisive for furthering the scientific career of Liebig, since Alexander von Humboldt was highly impressed by the great skill and talent of Liebig and — by recommendation of Humboldt — Liebig became Professor in Gießen in 1824 (at the young age of 21). The first (fulminato)metal complex, K[Ag(CNO)2], was also isolated by Liebig. Later, explosive (fulminato)metal complexes were prepared by Nef, Wieland, and especially by Lothar Wöhler and co‐workers. In Munich the HCNO structure of fulminic acid was established by its IR spectrum and the spectroscopic properties of (fulminato)metal complexes were studied. A series of new nonexplosive complexes could be obtained by dilution of the energy‐rich species with large cations or ligands. Recent X‐ray structure determinations have revealed the almost perfect linear, tetrahedral, square‐planar, or octahedral structures of these complexes with linear metal−C≡NO bonds, e.g. [Au(CNO)2]−, [Zn(CNO)4]2−, [Ni(CNO)4]2−, [Co(CNO)6]3−. DFT calculations have given very good agreement between the calculated and experimental structural parameters and CNO stretching frequencies. The (fulminato)metal complexes closely resemble the analogous cyano compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Metastable, Glasslike Solid‐State Phase of HAlO and Its Transformation to Al/Al2O3 Using a CO2 Laser
Authors: Veith Michael , Andres Kathrin , Stefan Faber  , Blin Joel , Zimmer Michael , Wolf Yan , Schnöckel Hansgeorg , Köppe Ralf , de Masi Remo , Hüfner Stefan 
Published: December 2003

AbstractBis(tert‐butoxyaluminum dihydride) (tBuOAlH2)2 decomposes on metal surfaces heated to 250 °C (Fe, Ni, Cu, Pt) and under reduced pressures of 0.01−0.1 atm with elimination of dihydrogen and isobutene to form a glasslike, amorphous film, which is composed of equimolar parts of hydrogen, aluminum and oxygen (elemental analysis, EDX analysis). The gases eliminated during this process were characterized by mass spectroscopy (H2, isobutene) or by infrared matrix techniques (isobutene). The exclusive binding of hydrogen to aluminum is deduced from IR spectroscopy of the HAlO film and of its deuterated form DAlO. The HAlO layer (which shows no X‐ray diffraction pattern), when heated to 450 °C or when exposed to a CO2 laser, loses hydrogen and transforms to an almost stoichiometric composite with nanoscale crystalline aluminum and aluminum oxide (Al/Al2O3) as ingredients. This transformation may be followed by IR spectroscopy, by 27Al MAS NMR or by XPS, the latter showing different signals (Al, 2p electrons, Mg‐Kα, θ = 0°) for HAlO (74.2 eV) and for the composite (Al: 72.1 eV, Al2O3: 75.3 eV). Microstructures that are characterized by different chemical compositions and different optical contrasts of the “drawing”, relative to the surrounding matrix, may be generated with an X/Y‐table and a CO2 laser. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Stoichiometric Control of the Magnetic Properties in Copper(II) Cyano‐Bridged Bimetallic Complexes
Authors: Coronado Eugenio , Giménez‐Saiz Carlos , Nuez Alicia , Sánchez Víctor , Romero Francisco M. 
Published: December 2003

AbstractControl of the Cu2+ ion coordination environment affords a 1D, magnetically diluted compound, [Cu(cis‐chxn)2]3[Fe(CN)6]2·7H2O (1) and the 2D ferromagnetic material [Cu(cis‐chxn)]3[Fe(CN)6]2·6H2O (2) with a critical temperature, Tc, of 3.5 K. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Structure and Magnetic Properties of a New Iron Arsenate, [C10N4H28][{FeF(OH)(HAsO4)}4], with a Layer Structure
Authors: Chakrabarti Sandip , Pati Swapan K. , Green Mark A. , Natarajan Srinivasan 
Published: December 2003

AbstractThe reaction of FeCl3·6H2O, H3AsO4, HF and 1,4‐bis(3‐aminopropyl)piperazine under solvothermal conditions gives rise to a new iron arsenate, [C10N4H28][{FeF(OH)(HAsO4)}4] (I) with a layered structure. The cell parameters are monoclinic, space group = P21/n (no.14), M = 1143.08, a = 9.6320(3), b = 8.3598(3), c = 10.7794(1) Å, β = 115.036(1)°, V = 786.42(4) Å3, Z = 4, R1 = 0.0492, wR2 = 0.1227 [1114 observed reflections with I > 2σ(I)]. The connectivity between FeO3F2(OH) octahedra and HAsO4 tetrahedra forms a secondary building unit (SBU) of the type SBU‐4. The SBU‐4 units are linked together to form a layer structure with apertures formed by 8‐T atoms (T = Fe, As). The amine molecules are disordered and occupy the inter‐lamellar region. To the best of our knowledge, I is the first example of an iron arsenate structure formed from only one type of secondary building unit, SBU‐4. A dimer model has been used to describe the magnetic behavior. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Theoretical Gas‐Phase Stabilities of α‐Trimethylsilyl‐Substituted Tertiary Carbenium Ions
Authors: Grunenberg Jörg , Laschat Sabine , Dickner Tim 
Published: December 2003

AbstractTheoretical hydride ion affinities in the gas phase are presented for α‐SiMe3‐substituted tertiary carbenium ions. Thermodynamic stabilization of the ”nascent“ ions by a single trimethylsilyl group is weaker than by atert‐butyl group but comparable to the effect of a methyl group. In the case of the cyclopropenylium cation, the stabilization by a trimethylsilyl group even exceeds the effectiveness of atert‐butyl group. Compliance constants are used to quantify the chemical concept of hyperconjugation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)