bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resonance‐Assisted Intramolecular Chalcogen–Chalcogen Interactions?
Authors: Sanz Pablo , Yáñez Manuel , Mó Otilia 
Published: September 2003

AbstractHigh‐level B3LYP/6‐311+G(3df,2p) density functional calculations have been carried out for a series of saturated chalcogenoaldehydes: CH(X)‐CH2‐CH2YH (X, Y=O, S, Se, Te). Our results indicate that in CH(X)‐CH2‐CH2YH (X=Y=O, S, Se) the XH⋅⋅⋅X intramolecular hydrogen bond (IHB) competes in strength with the X⋅⋅⋅XH chalcogen–chalcogen interaction, while the opposite is found for the corresponding tellurium‐containing analogues. For those derivatives in which X≠Y, X being the more electronegative atom, the situation is more complicated due to the existence of two non‐equivalent XH and YH tautomers. The YH tautomer is found to be lower in energy than the XH tautomer, independently of the nature of X and Y. For X=O, S, Se and Y=S, Se the most stable conformerbis the one exhibiting a YH⋅⋅⋅X IHB. Conversely when Y=Te, the chelated conformerd, stabilized through a X⋅⋅⋅YH chalcogen–chalcogen interaction is the global minimum of the potential energy surface. Systematically the IHB and the chalcogen–chalcogen interactions observed for saturated compounds are much weaker than those found for their unsaturated analogues. This result implies that the nonbonding interactions involving chalcogen atoms, mainly Se and Te, are not always strongly stabilizing. This conclusion is in agreement with the fact that intermolecular interactions between Se and Te containing systems with bases bearing dative groups are very weak. We have also shown that these interactions are enhanced for unsaturated compounds, through an increase of the charge delocalization within the system, in a mechanism rather similar to the so call Resonance Assisted Hydrogen Bonds (RAHB). The chalcogen–chalcogen interactions will be also large, due to the enhancement of the X→Y dative bond, if the molecular environment forces the interacting atoms X and Y to be close each other.
Scope, Kinetics, and Mechanistic Aspects of Aerobic Oxidations Catalyzed by Ruthenium Supported on Alumina
Authors: Yamaguchi Kazuya , Mizuno Noritaka 
Published: September 2003

AbstractThe Ru/Al2O3 catalyst was prepared by modification of the preparation of Ru(OH)3⋅n H2O. The present Ru/Al2O3 catalyst has high catalytic activities for the oxidations of activated, nonactivated, and heterocyclic alcohols, diols, and amines at 1 atm of molecular oxygen. Furthermore, the catalyst could be reused seven times without a loss of catalytic activity and selectivity for the oxidation of benzyl alcohol. A catalytic reaction mechanism involving a ruthenium alcoholate species and β‐hydride elimination from the alcoholate has been proposed. The reaction rate has a first‐order dependence on the amount of catalyst, a fractional order on the concentration of benzyl alcohol, and a zero order on the pressure of molecular oxygen. These results and kinetic isotope effects indicate that β‐elimination from the ruthenium alcoholate species is a rate‐determining step.
Supramolecular Spintronic Devices: Spin Transitions and Magnetostructural Correlations in [Fe4IIL4]8+ [2×2]‐Grid‐Type Complexes
Authors: Ruben Mario , Breuning Esther , Lehn Jean‐Marie , Ksenofontov Vadim , Renz Franz , Gütlich Philip , Vaughan Gavin B. M. 
Published: September 2003

AbstractThe magnetism of a series of tetranuclear complexes of the [FeII4L4](X)8 [2×2]‐grid‐type was investigated, revealing the occurrence of spin transition behavior within this class of compounds. The phenomenon depends directly on the nature of the substituent R1 in the 2‐position on the central pyrimidine group of the ligand L. All FeII ions in compounds with R1 substituents favoring strong ligand fields (R1=H; OH) remain completely in the diamagnetic low‐spin state. Only complexes bearing R1 substituents attenuating the ligand field by steric (and to a lesser extent electronic) effects (R1=Me; Ph) exhibit spin transition behavior triggered by temperature. In general, gradual and incomplete transitions without hysteresis were observed for magnetically active complexes. The systems described provide approaches to the development of (supra)molecular spintronics.
Square‐Planar Coordinated Polyanions of Palladium, Platinum, and Gold Stannaborate [SnB11H11]2− Coordination Chemistry
Authors: Marx Thiemo , Mosel Bernd , Pantenburg Ingo , Hagen Siegbert , Schulze Herbert , Wesemann Lars 
Published: September 2003

AbstractThe tetrasubstituted polyanions of platinum, palladium, and gold [M(SnB11H11)4]x− (x=6, M=Pd, Pt; x=5, M=Au) have been prepared and characterized by single‐crystal X‐ray diffraction, elemental analysis, IR, Raman, 11B, and 119Sn heteronuclear NMR spectroscopy. In the case of the platinum derivative [Bu3MeN]6[Pt(SnB11H11)4] (2) 119Sn Mössbauer spectroscopy has been carried out. The isolated salts are stable towards moisture and air and the complexes 2 and 3 were treated with 1,3‐bis(diphenylphosphino)propane (dppp) to give the respective substitution products [Bu3MeN]2[(dppp)M(SnB11H11)2] (M=Pd, Pt).
Gold Catalysis: Efficient Synthesis and Structural Assignment of Jungianol and epi‐Jungianol
Authors: Hashmi A. Stephen K. , Ding Li , Bats Jan W. , Fischer Peter , Frey Wolfgang 
Published: September 2003

AbstractStarting from 2‐methylfuran and crotonaldehyde, both jungianol and epi‐jungianol were prepared by a six‐step sequence including a gold‐catalyzed arene synthesis and a photochemical SN2‐like reduction with lithium aluminum hydride. Not a single protective group was needed in the entire synthesis. With both diastereomers in hand, the stereochemical assignment in the literature could be corrected by means of a thorough 1H NMR spectroscopic analysis and an X‐ray diffraction study on an epi‐jungianol derivative.
Chiral Pyrimidine Metallacalixarenes: Synthesis, Structure and Host–Guest Chemistry
Authors: Barea Elisa , Navarro Jorge A. R. , Salas Juan M. , Quirós Miguel , Willermann Michael , Lippert Bernhard 
Published: September 2003

AbstractA set of enantiomerically pure cyclic multinuclear complexes with the formula cis‐[a2PdL]nn+ [a2=(R,R)‐1,2‐diaminocyclohexane (R,R‐dach), (S,S)‐1,2‐diaminocyclohexane (S,S‐dach); n=4, 6; LH=2‐hydroxypyrimidine (2‐Hpymo), 4,6‐dimethyl‐2‐hydroxypyrimidine (2‐Hdmpymo) and 4‐hydroxypyrimidine (4‐Hpymo)] were obtained by reaction of cis‐[a2Pd(H2O)2]2+ and LH in aqueous media. The polynuclear complexes were studied by 1H NMR spectroscopy and X‐ray crystallography. These studies revealed that the N1,N3‐bridging mode exhibited by the pyrimidine moieties is ideally suited for formation of inorganic analogues of calixarenes (metallacalixarenes) in a self‐assembly process. The most stable species are the tetranuclear metallacalix[4]arenes, which are obtained in all cases. Hexanuclear species, namely, [a2Pd(2‐dmpymo)]66+, were also isolated and fully characterised. 1H NMR experiments show conversion of [a2Pd(2‐dmpymo)]66+ to [a2Pd(2‐dmpymo)]44+ on heating. Analogously to organic calixarenes, these systems are also capable of incorporating hard metal ions at the oxo surface. Additionally, investigations on the receptor properties of these metallacalixarenes towards mononucleotides showed that enantioselective recognition processes occur in aqueous media.
Review: Different types of ordering
Authors: Hauck J. , Mika K. 
Published: September 2003

AbstractHomogeneous structures AxBywith identical A–A or B–B self‐coordination numbersT1,T2,T3, of nearest, next‐nearest and third neighbors are selected. The maximumTivalues are 2 2 2 (1D row), 6 6 6 (2D hexagonal net) and 12 6 24 (3D cubic close‐packing). ReducedT1orT2values for AxBycan be related with attractive or repulsive A–A (or B–B) interactions. A single set ofT1T2T3; y/x values was obtained for y/x = 1–4 and 6. The y/x = 2 structures of three equivalent positions A, B and C are unfavourable for A = ⊕ and B = ⊖ charge or direction of magnetic moments. The spatial distribution of positive and negative potential near A+and B−positions gives rise to neutral C positions. Frustrated magnetic moments at C positions are disordered. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transmission spectra of crystals at elevated temperatures for the calculation of internal radiant heat transport during crystal growth – Part 1: The spectrometer and its performance
Authors: Schwabe D. , Polity A. 
Published: September 2003

AbstractWe report the construction, operation and performance of a transmission spectrometer for the visible to the IR (up to 3.5 μm wavelength) to measure crystals up to a temperature of 1400 °C. The spectral resolution is almost comparable to that of a commercial spectrometer. The performance of the spectrometer and some problems are demonstrated by spectra of YAG : Nd at different temperatures. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and chemical composition of LiB3O5 surfaces
Authors: Atuchin V. V. , Kesler V. G. , Lisova I. A. , Pokrovsky L. D. , Pylneva N. A. , Yurkin A. M. 
Published: September 2003

AbstractThe electronic and structural properties of LiB3O5 (LBO) surfaces have been studied by X‐ray photoemission spectroscopy (XPS) and reflectance high‐energy electron diffraction (RHEED). The as‐grown (110) crystal face and mechanically polished (001) surfaces have been investigated comparatively. Electronic structure of LBO has been determined on as‐grown (110) crystal face previously cleaned by chemical etching with RHEED control. The correlation of valence band structure and measured binding energies with earlier reported results has been discussed. Core‐level spectroscopy reveals strong enriching of mechanically polished LBO surface with carbon, when nanodiamond powder is used as an abrasive. So high carbon level as C:B = 0.7 has been observed at the surface while the ratio Li:B:O remains according to LBO chemical composition. The association of LBO Kikuchi‐lines with strong background has been shown by RHEED analysis of the surface. Thus, the polished LBO surface constitutes a high structure quality LBO with the inclusions of some amorphous carbon compound. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystal and molecular structure of 2,6‐bis(4‐chlorophenyl)‐3‐phenylpiperidin‐4‐one
Authors: Ompraba G. , Srinivasan M. , Perumal S. , Sekar K. , Choudhury A. R. , Guru Row T. N. , Rafi Z. A. 
Published: September 2003

AbstractThe crystal structure of the title compound is described. The chemical formula of the compound is C23H19Cl2NO. The compound is found to crystallize in monoclinic system with space group P21/c, Z = 4. The unit cell dimensions are a = 15.137(3) Å, b = 8.9171(18) Å, c = 14.779(3) Å, β = 91.461(4)° and V = 1994.2(7) Å3, Dcalc = 1.320 gcm‐3. The final R factor is 4.4%. The central piperidone ring of the molecule adopts a slightly distorted chair conformation, the mean torsion angle being 52.3°; the phenyl rings are planar. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Toroidal Main Group Macrocycles: New Opportunities for Cation and Anion Coordination
Authors: Doyle Emma L. , Riera Lucía , Wright Dominic S. 
Published: September 2003

AbstractInorganic macrocycles, possessing molecular frameworks composed entirely of elements other than carbon, are rare. Even rarer are species analogous to classical organic macrocycles (like crown ethers) that possess the potential ability to coordinate metal ions within their cavities. Recent studies reveal an emerging structural class of valence‐isoelectronic main‐group ligands of general formula [{E(µ‐E′R)}2Y]nx−, which possess fascinating coordination characteristics. Such species can coordinate metal ions within their cavities (using the donor centres Y and E′), their peripheral donor centres (E′) (in an exo fashion) and are also capable of coordinating anions (where Y = N−H). This short review highlights the recent synthetic and structural studies of these unusual ligand systems and pinpoints potential future areas of development. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Monomeric Magnesium and Calcium Complexes Containing the Bidentate, Dianionic 1,2‐Bis[(2,6‐diisopropylphenyl)imino]acenaphthene Ligand
Authors: Fedushkin Igor L. , Skatova Alexandra A. , Chudakova Valentina A. , Fukin Georgy K. , Dechert Sebastian , Schumann Herbert 
Published: September 2003

AbstractThe reduction of 1,2‐bis[(2,6‐diisopropylphenyl)imino]acenaphthene (2,6‐iPr2C6H3‐BIAN) with metallic magnesium or calcium in THF affords the monomeric complexes (2,6‐iPr2C6H3‐BIAN)Mg(THF)3 (1) and (2,6‐iPr2C6H3‐BIAN)Ca(THF)4·(THF)1/2 (2). The crystallisation of 1 and 2 from benzene causes the removal of one of the coordinated THF molecules, yielding (2,6‐iPr2C6H3‐BIAN)Mg(THF)2·(C6H6)1/2 (3a) and (2,6‐iPr2C6H3‐BIAN)Ca(THF)3 (4). Repeated recrystallisation of 1 from benzene gives (2,6‐iPr2C6H3‐BIAN)Mg(THF)2·(C6H6)2 (3b). Although the crystals of 3a and 3b differ in colour and in their crystallographic parameters, their molecular dimensions are very similar. Recrystallisation of 1 from pyridine produces (2,6‐iPr2C6H3‐BIAN)Mg(py)3·(py)2 (5). Complexes 1−5 have been characterised by elemental analysis, UV, IR and 1H NMR spectroscopy, as well as by single‐crystal X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Structure of a Monomeric Chiral Lithium Dialkylaluminium Amide Derived from Schöllkopf’s Bis‐lactim Ether and α‐(Methylbenzyl)benzylamine
Authors: Andrews Philip C. , Maguire Melissa , Pombo‐Villar Esteban 
Published: September 2003

AbstractCrystals of a monomeric lithium dialkylaluminium amide containing two different chiral amide moieties have been isolated from the reaction of lithiated Schöllkopf’s bis‐lactim ether complexed by pmdta with the diethylaluminium amide of (S)‐α‐(methylbenzyl)benzylamine, with single crystal X‐ray diffraction revealing a migration of the Li cation in the aluminate from its initial position on the pyrazine ring of the lactim ether precursor. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A Solid‐State, Solution, and Theoretical Structural Study of Kinetic and Thermodynamic Lithiated Derivatives of a Simple Diazomethane and Their Reactivities Towards Aryl Isothiocyanates
Authors: Armstrong David R. , Davies Robert P. , Haigh Robert , Hendy Mark A. , Raithby Paul R. , Snaith Ronald , Wheatley Andrew E. H. 
Published: September 2003

Abstract(Trimethylsilyl)diazomethane (1‐H) reacts with nBuLi in THF at elevated temperature to afford (previously reported) 1‐Li·3/2THF. However, reaction in hexane/TMEDA at low temperature affords instead the N‐lithiate Me3SiCNNLi·TMEDA (9), which is a novel “open” pseudo‐cubic tetramer in the solid state. Variable‐temperature NMR spectroscopy suggests that N‐metallated 9, apparently the kinetic product of the reaction, irreversibly rearranges at high temperature in solution to give the thermodynamically preferred C‐lithiated isomer. These observations, supported by DFT calculations, influence our understanding of the reactivity of lithiated diazomethanes towards aryl isothiocyanates, suggesting as they do that previously observed product selectivity in these reactions is critically dependent on temperature control exercised during the process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Sodiated β‐Diphosphonate Carbanions: Characterization of the Tetrameric Cubane and the Hexameric Ladder Complexes [{(iPrO)2P(O)}2CHNa]4and [{(EtO)2P(O)}2CHNa]6
Authors: Nassar Roger , Beatty Alicia M. , Henderson Kenneth W. 
Published: September 2003

AbstractReaction of the methylene diphosphonates [(RO)2P(O)]2CH2, where R =iPr or Et, with the metalating reagents NaH,nBuNa or the superbasic mixturetBuONa/nBuLi leads to monodeprotonation, and formation of the complexes [{(iPrO)2P(O)}2CHNa]4(1) and [{(EtO)2P(O)}2CHNa]6(2). Single‐crystal X‐ray diffraction studies revealed that1is tetrameric in the solid state, with a central Na4O4cubane core. Each metal in1is rendered pentacoordinate by binding to three μ3‐O phosphoryl bridges within the cubane, a chelating phosphoryl unit, and also a singleiPrO group. In contrast, the structure of2is hexameric, and is composed of an unusual six‐rung Na6O6ladder core. Three distinct sodium environments as well as μ1‐, μ2‐ and μ3‐O phosphoryl units are present within the ladder framework. No Na−C interactions are present in either1or2. All of the six‐membered NaOPCPO chelate rings display localized P=O double bonds and partial multiple bonding on the P−C−P linkages (mean P−O: 1.49 Å, and mean P−C: 1.69 Å). Ab initio molecular orbital calculations (HF/6−31G*) on model complexes indicate that the hexameric arrangement found for2is thermodynamically more stable than the cubane structure of1, in the absence of steric effects. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Structures of Alkali Metal Amides Derived from the Ligands [N(SiMe2Ph)(SiMe3)]−, [N(tBu)(SiMe3)]−, [N(Ph)(2‐C5H4N)]−, and [N(2‐C5H4N)2]−
Authors: Antolini Floria , Hitchcock Peter B. , Khvostov Alexei V. , Lappert Michael F. 
Published: September 2003

AbstractThe following crystalline complexes are reported: [(M{μ‐N(SiMe2Ph)(SiMe3)})2]n [the cis complex for n = 1 and M = Li (1); and the trans complexes with n = ∞ and M = Na (2), K (4), Rb (5), Cs (6)], [(Na{μ‐trans‐N(SiMe2Ph)(SiMe3)})2(tmeda)] (3), [(K{μ‐trans‐N(tBu)(SiMe3)})4(η‐C6H6)2] (7), [(K{μ‐trans‐N(Ph)(2‐C5H4N)})2(μ′‐thf)3]∞ (8), and [K{μ‐N(2‐C5H4N)2}]∞ (9). Each, except 3, was obtained by metallation of the appropriate secondary amine with LinBu (for 1), MBzl [M = Na (for 2), K (for 4 and 7), Rb (for 5), Cs (for 6)], or KH (for 8 and 9); treatment of 2 with an excess of tmeda yielded 3. Each of 1−9 has an unusual, and in some cases unprecedented, molecular structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Characterization of the Very Bulky Phenols Ar*OH and Ar′OH (Ar* = C6H3‐2,6‐Trip2, Trip = C6H2‐2,4,6‐iPr3; Ar′ = C6H3‐2,6‐Dipp2, Dipp = C6H3‐2,6‐iPr2) and Their Lithium and Sodium Derivatives (LiOAr′)2 and (NaOAr*)2
Authors: Stanciu Corneliu , Olmstead Marilyn M. , Phillips Andrew D. , Stender Matthias , Power Philip P. 
Published: September 2003

AbstractThe very bulky phenols Ar*OH (1) and Ar′OH (2), where Ar* = C6H3‐2,6‐Trip2 (Trip = C6H2‐2,4,6‐iPr3) and Ar′ = C6H3‐2,6‐Dipp2 (Dipp = C6H3‐2,6‐iPr2), as well as their lithium and sodium derivatives (LiOAr*)2 (3), (LiOAr′)2 (4) and (NaOAr*)2 (5) have been synthesized and characterized. The terphenols 1 and 2 were obtained by the reaction of the aryllithium reagents with nitrobenzene and were isolated in ca. 70% yield. The lithium or sodium salts 3−5 were isolated by the reaction of 1 or 2 with nBuLi or sodium metal. All compounds were characterized spectroscopically, and by X‐ray crystallography in the case of 1, 2, 4 and 5. The large terphenyl substituents prevent hydrogen‐bonded association of the phenols 1 and 2. Instead, the O−H hydrogens interact with the π‐electron cloud on one of the flanking Trip or Dipp rings. The dimeric structures of 4 and 5 are relatively rare examples of structurally characterized alkali metal phenoxides that are unsolvated by internal electron pair donors or classical Lewis bases such as ethers or amines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Fluorite‐Related Phases in the System Li‐Pt‐Sn: Synthesis and Structures of Li2PtSn, Li3Pt2Sn3, Li2.27Pt2Sn3.73 and Li2.43Pt2Sn3.57
Authors: Hoffmann Rolf‐Dieter , Wu Zhiyun , Pöttgen Rainer 
Published: September 2003

AbstractThe intermetallic compounds Li2PtSn, Li3Pt2Sn3, Li2.27Pt2Sn3.73 and Li2.43Pt2Sn3.57 were synthesised by reaction of the elements in sealed tantalum tubes. They were investigated by X‐ray diffraction on powders and single crystals: F$\bar 4$
3m, a = 626.0(1) pm, wR2 = 0.0834, 70 F2 values, 7 variables for Li2PtSn; Ia$\bar 3$
, a = 1264.3(1) pm, wR2 = 0.0340, 416 F2 values, 23 variables for Li3Pt2Sn3; Ia$\bar 3$
, a = 1269.7(1) pm, wR2 = 0.1130, 521 F2 values, 24 variables for Li2.27(1)Pt2Sn3.73(1); Ia$\bar 3$
, a = 1266.6(1) pm, wR2 = 0.1094, 620 F2 values, 25 variables for Li2.43(1)Pt2Sn3.57(1). The latter refinement was based on a crystal twinned by merohedry. Li2PtSn crystallises with an ordered variant of the BiF3 type. The other stannides adopt a superstructure of the fluorite type where all three subcell axes are doubled. In Li3Pt2Sn3 the platinum atoms are located on the calcium sites while the tin and 1/3 of the lithium atoms are ordered on the fluorine site. The remaining lithium atoms fill octahedral voids of the fcc arrangement of platinum. The superstructure is discussed on the basis of a group‐subgroup scheme and experimental evidence is given for a solid solution Li3−xPt2Sn3+x. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Structure and Theoretical Studies of the Hydrido Inverse Crown [K2Mg2(NiPr2)4(μ‐H)2·(toluene)2]: a Rare Example of a Molecular Magnesium Hydride with a Mg‐(μ‐H)2‐Mg Double Bridge
Authors: Andrikopoulos Prokopis C. , Armstrong David R. , Kennedy Alan R. , Mulvey Robert E. , O’Hara Charles T. , Rowlings René B. 
Published: September 2003

AbstractReaction of benzylpotassium, n,s‐dibutylmagnesium and diisopropylamine in boiling toluene produces a rare example of a molecular magnesium hydride with a Mg‐(μ‐H)2‐Mg double bridge, in [K2Mg2(NiPr2)4(μ‐H)2·(toluene)2] (1). In an effort to rationalise the formation of 1, a series of DFT calculations were performed. This report of 1 establishes the first isostructural pair of Na and K complexes solvated by toluene to be reported in the Cambridge Crystallographic Database. In comparison with its previously reported Na analogue, 2, the metal‐arene centroid distances are considerably shorter (by 0.159 Å) in the new complex reported here. It was found that a hydrocarbon solution of 1 is capable of reducing benzophenone to benzhydrol in moderate yields (74%). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: Structures and Reactions of 1,3‐Diamidodilithium Complexes: the Hemisolvated l‐[CMe2{CHMeN(R)}2Li2·OEt2], the Unsolvated 1:1 Mixed Organo‐amidolithium u‐[CMe2{CHMeN(R′)}2·Li2·(nBuLi)2], and the Product of Oxidative Ring Closure, the Pyrazolidine l‐[(RNCHMe)2CMe2] (R = 2‐iPr‐C6H4; R′ = 2,6‐iPr2‐C6H3) (Eur. J. Inorg. Chem. 18/2003)
Authors: Carey David T. , Mair Francis S. , Pritchard Robin G. , Warren John E. , Woods Rebecca J. 
Published: September 2003

AbstractThe cover picture shows an Li2N2 unit which is prevented by the bulk of the aryl substituents from stacking with another to form a cubic cluster. The diethyl ether solvent traps this fragment of a molecule which, in the absence of diethyl ether, precipitates as a powder, possibly by lateral association of Li2N2 rings to form an infinite ladder in a manner first suggested by Ronald Snaith, whose memory is honoured in this special edition of EurJIC. Details are presented in the article by F. Mair et al. on p. 3464 ff.
Synthesis of Amino Acids with Unnatural Nucleobases or Chromophores Suitable for Use in Model Electron‐Transfer Studies
Authors: Wagner Thomas , Davis William B. , Lorenz Katrin B. , Michel‐Beyerle Maria E. , Diederichsen Ulf 
Published: September 2003

AbstractWe describe the syntheses of Boc‐protected amino acids bearing the chromophores pyromellitic diimide, naphthalene diimide, and pyrene in their side chains, as well as nucleo amino acids with the artificial purines 7‐carbaguanine, 7‐carbaadenine, isoadenine, and 7‐carbaisoadenine covalently linked to the alanyl side chain. These amino acids incorporating chromophores are suitable building blocks for incorporation into alanyl‐PNA for future investigations of the mechanism of nucleobase‐mediated electron transfer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)