bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of diastereomeric chlorophyll allomers by atmospheric pressure chemical ionisation liquid chromatography/tandem mass spectrometry
Authors: Walker J. Stuart , Jie Chi , Keely Brendan J.
Published: May 2003

Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry (APCI‐LC/MS) has been used for identification of the epimers of hydroxy, methoxy and methoxylactone allomers of chlorophyll a (132‐HO‐chl a, 132‐MeO‐chl a and 151‐MeO‐lact‐chl a), the hydroxy allomer of bacteriochlorophyll a (132‐HO‐bchl a) and the hydroxy and methoxylactone allomers of bacterioviridin a (132‐HO‐bvir a and 151‐MeO‐lact‐bvir a). The APCI mass spectra show that facile fragmentations involve the methoxyl or hydroxyl groups at the C‐132 or C‐151 chiral centres. Losses involving the C‐132 or C‐151 hydroxyl or methoxyl groups occur more easily from the S‐epimer than from the R‐epimer due to the greater relief of the steric strain associated with interaction with the bulky C‐17 substituent. The differences in mass spectrometric fragmentation can be used as a diagnostic tool for the assignment of the stereochemical configuration at the C‐132 or C‐151 chiral centres. Copyright © 2003 John Wiley & Sons, Ltd.
Isolation of ammonium‐N as 1‐sulfonato‐iso‐indole for measurement of δ15N
Authors: Johnston Andrew M. , Scrimgeour Charles M. , Kennedy Hilary , Handley Linda L.
Published: May 2003

The conversion of ammonium (NH4+) to 1‐sulfonato‐iso‐indole has been examined as a method for natural abundance measurement of δ15N of NH4+. The reaction is complete within 2 h and is based on the derivatisation of NH4+ by o‐phthaldialdehyde and sodium sulfite at a high pH, 11.2. The product is readily concentrated from dilute solutions by reverse‐phase solid‐phase extraction (SPE). The method is compound‐specific despite partial derivatisation of potentially interfering amino acids, as their derivatives are not extracted by SPE. δ15N values of NH4+ in KCL soil extracts can be measured within 48 h by automated continuous‐flow IRMS with a precision of 0.23‰ (1 SD). Parallel measurements of NH4+ standards of known δ15N are made to allow correction for the isotopic dilution by non‐sample NH4+. The practicality of this method is demonstrated by measuring the changes in NH4+ concentration and δ15N following the addition of urea as a nitrogen source to inorganic N‐depleted soil. Copyright © 2003 John Wiley & Sons, Ltd.
Confirmatory analysis of sulfonamide antibacterials in bovine liver and kidney: extraction with hot water and liquid chromatography coupled to a single‐ or triple‐quadrupole mass spectrometer
Authors: Bogialli Sara , Curini Roberta , Di Corcia Antonio , Nazzari Manuela , Sergi Manuel
Published: May 2003

A simple, specific, and rapid confirmatory method for determining 12 sulfonamide (SAs) antibacterials in bovine liver and kidney is presented. This method is based on the matrix solid‐phase dispersion technique with hot water as extractant followed by liquid chromatography/mass spectrometry (LC/MS) with an electrospray ion source. The method was tailored for use with both single‐quadrupole MS (I) and triple‐quadrupole MS (II) instruments. After acidification and filtration of the aqueous extract, a 250‐μL aliquot was injected into instrument I while only 25 μL was analyzed by instrument II. With instrument I MS data acquisition was performed in the selected ion monitoring (SIM) mode, selecting at least three ions for each target compound. With instrument II the selected reaction monitoring (SRM) mode with three fragmentation reactions for each compound was chosen. With the exception of sulfaquinoxaline (SQX), recovery of the analytes at the 50 ppb level in both liver and kidney was 72–96% with relative standard deviations (RSDs) ranging between 3 and 11%. The very poor recovery of SQX was due to its rapid enzymatic oxidation when in contact with the two tissues. With instrument I, limits of quantification (LOQs, S/N = 10) were 5–14 ppb of SAs. Even lower LOQs (1–8 ppb) were estimated by using instrument II, even though the extract volume analyzed was ten times lower than that with instrument I. With both matrices and using instrument I, severe ion signal suppression was experienced for the early‐eluted SAs when trying to fractionate analytes by using a short chromatographic run time. This effect was traced to polar endogenous co‐extractives eluted in the first part of the chromatographic run that interfered with gas‐phase ion formation for SAs. Adopting more selective chromatographic conditions minimized this effect. Copyright © 2003 John Wiley & Sons, Ltd.
Sample preparation effects in matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry of partially depolymerised methyl cellulose
Authors: Momcilovic Dane , Wittgren Bengt , Wahlund Karl‐Gustav , Karlsson Johan , Brinkmalm Gunnar
Published: May 2003

Methyl cellulose (MC) was partially depolymerised and the oligomers thus obtained were studied by matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS). The depolymerisation was either enzymatic or acidic. Fractions of enzymatically depolymerised MC were collected from size‐exclusion chromatography and subjected to a sample preparation investigation. Several MALDI matrices and solvents were evaluated. The results showed that the solvent choice had a significant effect on the measured degree of substitution (DS). Aprotic solvents produced higher DS values, which was most likely due to poor solubility of species with low DS. The obtained signal intensity, however, did not correlate with the solubility but seemed to be more dependent on certain matrix/solvent combinations. All the matrices attempted produced mass spectra with sufficient signal intensity for accurate peak area calculation. The choice of matrix did not have any significant effect on the measured DS. Sample spots obtained from organic solvents had a more homogeneous distribution of the analyte and smaller crystals than those obtained from water. This increased both the reproducibility and peak resolution and in addition the analysis time was shorter. DS measurements were performed on two acidically depolymerised MCs with different nominal DS values. It was easy to distinguish between the two MCs, and the measured DS values agreed well with the values supplied by the manufacturers. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of dinucleoside polyphosphates by matrix‐assisted laser desorption/ionisation post‐source decay mass spectrometry
Authors: Jankowski J. , Große‐Hüttmann P. , Zidek W. , Schlüter H.
Published: May 2003

Dinucleoside polyphosphates are a group of intra‐ and extracellular mediators controlling numerous physiological functions. In this study dinucleoside polyphosphates were examined by positive ion matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MADLI‐TOFMS). 3‐Hydroxypicolinic acid was used as UV‐absorbing matrix. For the individual dinucleoside polyphosphates ApnA (n = 2–7), ApnG (n = 2–6) and GpnG (n = 2–6), MALDI post‐source decay (PSD) mass spectra were measured. Each mass peak in the MALDI‐PSD mass spectra could be assigned to individual fragments of dinucleoside polyphosphates. The comparison of the fragmentation patterns of the dinucleoside polyphosphates presented here demonstrates that dinucleoside polyphosphates preferably cleave to fragment ions consisting of the corresponding mononucleoside polyphosphates as well as the corresponding nucleosides and bases during flight in the field‐free drift path of the MALDI mass spectrometer. Therefore, the MALDI‐PSD approach described here is suitable for identification of other dinucleoside polyphosphates. The present MALDI‐PSD mass spectra may be used as MALDI‐PSD mass reference spectra for future identification of dinucleoside polyphosphates and other nucleotides. Copyright © 2003 John Wiley & Sons, Ltd.
A standard protocol for single nucleotide primer extension in the human genome using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Wise Cheryl A. , Paris Maxime , Morar Bharti , Wang Wei , Kalaydjieva Luba , Bittles Alan H.
Published: May 2003

Analysis of single nucleotide polymorphisms (SNPs) has become an increasingly important area of research, with numerous applications in medical genetics, population genetics, forensic science, and agricultural biotechnology. Large‐scale SNP analyses require the development of methodologies that are economical, flexible, accurate and capable of automation. Primer extension in conjunction with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) is currently emerging as a potential method for high‐throughput SNP genotyping. We have evaluated a number of published primer extension methods and refined a simple and robust protocol to analyze human autosomal disease‐causing mutations and population genetic markers on the Y‐chromosome. Twelve different variant sites were examined, and homozygotes, heterozygotes and hemizygotes were accurately typed. A 100% concordance was observed between SNP genotypes obtained using the MALDI‐TOFMS technique and alternative genotyping methods, such as restriction fragment length polymorphism (RFLP) assays and denaturing high‐performance liquid chromatography (DHPLC). Since multiple polymorphisms can be detected in single reactions, the method provides a cost‐effective approach for SNP analysis. The protocol is also extremely flexible (able to accommodate new markers) and can be adapted to a number of platforms without the use of commercial kits. Copyright © 2003 John Wiley & Sons, Ltd.
Simultaneous quantitation of enalapril and enalaprilat in human plasma by 96‐well solid‐phase extraction and liquid chromatography/tandem mass spectrometry
Authors: Lee Jaeick , Son Junghyun , Lee Mijin , Lee Kyung Tae , Kim Dong‐Hyun
Published: May 2003

A sensitive and rapid method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) combined with rapid solid‐phase extraction (SPE) has been developed and validated for the quantitative determination of enalapril and its active metabolite enalaprilat in human plasma. After addition of internal standard to human plasma, samples were extracted by 96‐well SPE cartridge. The extracts were analyzed by HPLC with the detection of the analyte in the multiple reaction monitoring (MRM) mode. This method for the simultaneous determination of enalapril and enalaprilat was accurate and reproducible, with respective limits of quantitation of 0.2 and 1.0 ng/mL in plasma. The standard calibration curves for both enalapril and enalaprilat were linear (r2 = 0.9978 and 0.9998) over the concentration ranges 0.2–200 and 1.0–100 ng/mL in human plasma, respectively. The intra‐ and inter‐day precision over the concentration range for enalapril and enalaprilat were lower than 13.3 and 15.4% (relative standard deviation, %RSD), and accuracy was between 89.2–105.0 and 91.9–104.7%, respectively. Copyright © 2003 John Wiley & Sons, Ltd.
Approaches towards the automated interpretation and prediction of electrospray tandem mass spectra of non‐peptidic combinatorial compounds
Authors: Klagkou Katerina , Pullen Frank , Harrison Mark , Organ Andy , Firth Alistair , Langley G. John
Published: May 2003

Combinatorial chemistry is widely used within the pharmaceutical industry as a means of rapid identification of potential drugs. With the growth of combinatorial libraries, mass spectrometry (MS) became the key analytical technique because of its speed of analysis, sensitivity, accuracy and ability to be coupled with other analytical techniques. In the majority of cases, electrospray mass spectrometry (ES‐MS) has become the default ionisation technique. However, due to the absence of fragment ions in the resulting spectra, tandem mass spectrometry (MS/MS) is required to provide structural information for the identification of an unknown analyte. This work discusses the first steps of an investigation into the fragmentation pathways taking place in electrospray tandem mass spectrometry. The ultimate goal for this project is to set general fragmentation rules for non‐peptidic, pharmaceutical, combinatorial compounds. As an aid, an artificial intelligence (AI) software package is used to facilitate interpretation of the spectra. This initial study has focused on determining the fragmentation rules for some classes of compound types that fit the remit as outlined above. Based on studies carried out on several combinatorial libraries of these compounds, it was established that different classes of drug molecules follow unique fragmentation pathways. In addition to these general observations, the specific ionisation processes and the fragmentation pathways involved in the electrospray mass spectra of these systems were explored. The ultimate goal will be to incorporate our findings into the computer program and allow identification of an unknown, non‐peptidic compound following insertion of its ES‐MS/MS spectrum into the AI package. The work herein demonstrates the potential benefit of such an approach in addressing the issue of high‐throughput, automated MS/MS data interpretation. Copyright © 2003 John Wiley & Sons, Ltd.
Experimental Testing of a Gauge Based Collision Detection Mechanism for a New Three‐Degree‐of‐Freedom Flexible Robot
Authors: García A. , Feliu V. , Somolinos J. A.
Published: May 2003

The use of flexible robots can be easily justified in two main cases: (1) when the weight of the robot has to be minimized and (2) when collisions between the robot and the environment are foreseen, since a flexible, lightweight robot implies less impact energy. The position control of these robots has already been analyzed in previous communications. However, the second of these cases justifying the use of flexible robots requires further consideration, leading to the development of a force controller. Inmost up to date analysis the force control is studied beginning from a known contact point at a given collision time. In a more realistic approach, however, an accurate detection of the collision would be needed prior to dealing with the force control. After developing a reliable position controller for a three‐degree‐of‐freedom flexible robot using strain gauges placed over the robot structure, in this paper we deal with the possibility of carrying out the collision detection for the same prototype. This has been easily achieved by analyzing some estimated signals such as tip position and tip velocity. However, a complete analysis of the information obtained with the sensors has been required to obtain those estimates and a signal processing scheme had to be devised for a previous filtering of the original signals from the sensors (encoders and strain gauges). This work has been carried out as a first step towards the position/force control. Experimental results on a three‐degree‐of‐freedom flexible arm prototype are presented to verify how well this method performs. © 2003 Wiley Periodicals, Inc.
Mechatronic Design and Locomotion of Amoebot—A Metamorphic Underwater Vehicle
Authors: Chen I‐Ming , Li Hsi‐Shang , Cathala Arnaud
Published: May 2003

The Metamorphic Underwater Vehicle (MUV) is a vehicle that propels in the water by continuously changing the shape of its body similar to the motion of the microorganism amoebae. In this article, we describe the basic design of Amoebot, a plastic MUV that achieves shape‐changing capability through the inflation and deflation of water‐filled balloons. A sequence of inflation and deflation procedures can be taken to produce cyclic swimming shapes that propel the MUV. Swimming shapes similar to the microorganism amoebae have been successfully reproduced by present Amoebot. The mechanical system designed proves to be very reliable and flexible in producing desired body shapes. The physical shape of the Amoebot is analyzed numerically and its variation in time during the swim can be expressed explicitly. By formulating sets of idealized swimming rules based on the changing shape, simulations are carried out to predict the trajectory and study the pseudo dynamics of the swimming of Amoebot. Possible applications of this type of underwater vehicle are discussed. © 2003 Wiley Periodicals, Inc.
Design of rational agents for performing speech acts intentionally in multiagent environment
Authors: Takata Shiro , Igarashi Yoshime , Nide Naoyuki , Enomoto Mika , Mase Kenji , Nakatsu Ryohei
Published: May 2003

This paper presents the basic design for rational agents who intentionally perform speech acts in multiagent environments for the purpose of problem‐solving in collaboration with humans or other agents. The authors aim at construction of a rational agent with the BDI (belief, desire, intention) architecture. The rational agent aims at achieving her given goal and selects a plan carefully on the basis of her belief. She then forms the selected plan as her intention, as her mental state to control future deliberation. If the precondition for the intention is satisfied, a speech act composing that intention is intentionally performed. In this paper, the FIPA (Foundation of Intelligent Physical Agents)‐conformant primitive communicative acts and protocols are first defined as speech acts of the agent. The extended BDI architecture is proposed in which conditional branching, synchronized waiting for a message, and so on, generated in the communication between agents by using speech acts, are directly represented in the body part of the plan. Then, information filtering by the researcher secretary agent in a laboratory tour guide system is considered, and the usefulness of the proposed method is demonstrated. Lastly, a problem is posed regarding a courteous rejection of a request from the user by the rational agent, which will be an important issue in the future. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(8): 77–88, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10114
Formal specification of components in a component‐based framework development method
Authors: Yoshida Kazuki , Honiden Shinichi
Published: May 2003

This paper presents a technique called FCF (Formally specified Component based Framework development method) to develop frameworks by connecting components whose functional aspects are formally specified. In FCF, three rules are imposed on component extraction/design from the perspectives of the framework's hot spot and its algebraic specification. Then, on the basis of the rules, problems for specifying the functional aspect of a framework which is composed by connecting components are clarified, and these are solved by a descriptive device and a theoretical extension of algebraic specification. Then, using these solutions, the components of business transaction processing extracted and designed following the rules are specified, from which the solutions are evaluated. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(8): 62–76, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10280
Deformation model of a human face based on measurements
Authors: Mizobuchi Tomoki , Hirota Koichi , Kaneko Toyohisa
Published: May 2003

This paper proposes a method for simulating a soft object in a virtual space. We employ a spring mass network to represent a human face, which is an example of a soft object. A bubble mesh algorithm is applied to CT data to obtain a network whose nodes are approximately equally spaced. For connecting bubble centers we devised a technique employing a Voronoi diagram. Softness is represented by a spring network model with springs assigned to edges connecting adjacent nodes. The spring constant is determined experimentally so that the measured softness is equal to the softness of a virtual object in terms of the relation between force and displacement. The nonlinearity of a spring is set at 80% of its depth, read from the CT data. A force feedback system using PHANToM was implemented in order to allow a sensation of virtually feeling and pushing a soft object. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(8): 33–41, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10320
Bayes code with singular prior
Authors: Takahashi Hayato
Published: May 2003

We study the asymptotic code lengths of sequences generated by smooth parametric models. We study especially the cases such that the parameters are in a set of Lebesgue measure 0. In general, for smooth parametric models, it is known that, under a suitable condition, the lower bound of the code length is −logP̂ + (k/2)logn + o(logn), except for parameters in a set of Lebesgue measure 0, where P̂ is the maximum likelihood, k is the dimension of the model, and n is a sample size. It is known that MDL coding and Bayes coding achieve this lower bound. In this paper we construct a code by Bayes mixture with a singular prior. The code shown in this paper has a shorter code length than MDL coding (log coefficient less than k/2) when the parameters are in a set of measure 0, and is considered to be intermediate between Shannon coding and MDL coding. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(8): 22–32, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10358
A networkwide backup system with inter‐memory autonomic copy mechanism
Authors: Mukai Ryo , Yamada Shigeki , Tanaka Satoshi , Tanaka Akira , Kubota Minoru , Kogiku Ichizo
Published: May 2003

We propose a networkwide backup system for a system composed of multiple primary nodes connected by a wide‐area network. The system enables us to implement the backup node physically far from the primary nodes. In this system, we can implement a replica of the primary node with low overhead, and the replica can start up when the primary node stops. The replica is made by serially transferring memory update information of a primary node to a backup node, by using a hardware‐based memory copying mechanism.

In addition, our system is transparent for application programs, that is, the applications are not aware of the switchover. Thus, we need no modification to the application software, and we can build a highly reliable system using existing software.

In the evaluation of a prototype system, the overhead for checkpoint processing was about 1.6 ms, and the processing time for switching to the backup node from the time fault detection was about 165 µs. This result means that our system is superior to the ordinary active replication system in terms of the overhead when the distance between a primary node and a backup node is larger than 160 km. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(8): 89–99, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1211
Development and evaluation of a mediabase system for supporting inductive knowledge acquisition
Authors: Funaoi Hideo , Kuroda Takayuki , Egami Eiji , Gotoh Youhei , Itami Makoto , Itoh Kohji
Published: May 2003

With the progress of computer applications to education, such facilities as databases and hypermedia have come into educational use in recent years. The mediabase system “ShareMedia” which is being developed in this study is a system that supports the description, sharing, retrieval, and examination of knowledge by students. In ShareMedia, a semantic frame is used by a community of students by common agreement. A rough semantic index is added to the media representation, so that the same community or the inheriting community can extract closely related media representations through such an index or its converted form and can use it for comparison and examination. It is intended in this study to support the inductive acquisition of generalized knowledge which applies to the domain under consideration, that is, Japanese geography and world geography as subjects in junior high school. A system was experimentally constructed and a preliminary experiment performed. The results suggested that the support of knowledge acquisition by ShareMedia browsing is useful in aiding the student to discover general knowledge and the rules in a domain with which the student is not familiar. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(8): 100–111, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1212
Ownership, organization, and private firms' efficient use of resources
Authors: Durand Rodolphe , Vargas Vicente
Published: May 2003

The principal–agent theory asserts that public firms' performance is driven by efficient capital and labor markets but is silent about non‐listed private companies, which are less permeable to market forces (both capital and labor) than are public companies. We propose and test a 2 × 2 framework distinguishing owner‐controlled vs. agent‐led firms from firms with a flat vs. multilayer organization. Our findings provide highly contrasted results and raise important issues for further study of private firms. Copyright © 2003 John Wiley & Sons, Ltd.
Pricing process as a capability: a resource‐based perspective
Authors: Dutta Shantanu , Zbaracki Mark J. , Bergen Mark
Published: May 2003

Strategists following the resource‐based view argue that firms can generate rents through value creation. To create value, firms develop and use resources and capabilities that other firms cannot imitate, trade for, or substitute other assets for. Even a firm that has created value, however, may not capture the potential rents associated with that value. To capture rents, a firm must set the right prices for what it sells. Most views of pricing assume that a firm can readily set appropriate prices. In contrast, we argue that pricing is a capability. To develop the ability to set the right prices, a firm must invest in resources and routines. We base our argument on a study of the pricing process of a large Midwestern manufacturing firm. We show that pricing resources, routines, and skills may help or inhibit a firm in setting the right price—and hence in appropriating value created. Our view of pricing as a capability contributes to the resource‐based view because it suggests that strategists should consider the portfolio of value creation and value appropriation capabilities a firm uses to create competitive advantage. Our view also contributes to economics because it suggests that strategic decisions about pricing capabilities have important implications for a fundamental economic action, determining prices. Managers in firms without effective pricing processes may be unable to set prices that reflect the wishes of its customers, so the customers may misuse their resources. As a result, resources may be used ineffectively. Our view of pricing as a capability therefore takes the resource‐based‐view straight to the heart of what is perhaps the central economic question: the best use of resources. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamic capabilities, social capital, and rent appropriation: ties that split pies
Authors: Blyler Maureen , Coff Russell W.
Published: May 2003

Who reaps the fruits of a dynamic capability? We argue that while social capital is essential for the acquisition, integration, and release of resources at the core of a dynamic capability, actors can also use social capital for personal gain. Thus, social capital may be a key to understanding both rent generation and rent appropriation. Even when causal ambiguity obscures individual contributions, they may use their social capital to establish credible claims on the rent. Specifically, employees who occupy structural holes, span organizational boundaries, or who are highly central may be most able to appropriate rent because their social capital grants credibility to their claims. Rent that is appropriated in this way may be unobservable in performance measures that fail to distinguish normal compensation from rent. We contribute by identifying the specific role of social capital in a dynamic capability and linking social capital to rent appropriation patterns. Copyright © 2003 John Wiley & Sons, Ltd.
Ein stabiles Trichlor‐oxyphosphoran mit einem Oxaphosphorinring
Authors: Gloede Jörg , Pieper Ursula , Costisella Burkhard , Krüger Ralph‐Peter
Published: May 2003

Das cyclische, arylsubstituierte Chlorphosphonit 3 reagiert mit Chlor zum Trichlor‐oxyphosphoran 4 (6, 6, 6‐Trichlor‐6H‐dibenzo[c, e]1, 2‐oxaphosphorin). Die Stabilität des Phosphorans ist lösungsmittelabhängig.
Single Crystal X‐ray Diffraction Study of CsHSi2O5
Authors: Dörsam Guido , Kahlenberg Volker , Fischer Reinhard X.
Published: May 2003

Hydrothermally synthesized CsHSi2O5 was studied by single‐crystal X‐ray diffraction. The compound is orthorhombic (space group Pnma). Unit cell parameters are a = 4.9758(3), b = 8.8089(6), c = 12.9295(9) Å with four formula units per cell. The structure was solved by direct methods and refined to a residual R1 = 0.025 for 621 independent observed reflections with I > 2σ(I) and 41 parameters. Residual electron densities were used to locate positions of the H atoms. They are part of silanol groups and show a disorder involving two positions related by a center of symmetry. The resulting O—H···O distance of 2.44 Å is one of the shortest hydrogen bonded O···O distances in inorganic compounds containing silanol groups. The structure belongs to the class of unbranched zweier double chain silicates. The [Si2O4(OH)—] chains run parallel [100]. Cesium cations providing additional linkage between the anionic ribbons reside in voids between the chains and coordinate to nine oxygen ligands.
Polysulfonylamine. CLXIII [1] Kristallstrukturen von Metall‐di(methansulfonyl)amiden. 12 [1] Das orthorhombische Doppelsalz Na2Cs2[(CH3SO2)2N]4·3H2O: Ein dreidimensionales Koordinationspolymer aus (Caesium‐Anion‐Wasser)‐Schichten und intercalierten Natriumionen
Authors: Moers Oliver , Blaschette Armand , Jones Peter G.
Published: May 2003

Die Kristallpackung des dreidimensionalen Koordinationspolymers Na2Cs2[(MeSO2)2N]4·3H2O (orthorhombisch, Raumgruppe Pna21, Z′ = 1) zeigt teilweise Übereinstimmung mit der des zuvor beschriebenen Natrium‐Kalium‐Doppelsalzes Na2K2[(MeSO2)2N]4·4H2O (tetragonal, P43212, Z′ = 1/2). In der vorliegenden Struktur finden sich vier mehrzähnig koordinierende unabhängige Anionen, drei unabhängige Aquoliganden und zwei Arten von Caesiumionen in Monoschicht‐Substrukturen angehäuft, die paarweise über ein [Cs(1)—H2O—Cs(2)]‐Motiv zu Doppelschichten assoziiert sind. Auf diese Weise gelangt jedes Cs+ zu einer unregelmäßigen (O8N2)‐Koordination durch Bindungswechselwirkungen mit zwei N, O‐chelatisierenden und zwei O, O‐chelatisierenden Anionen sowie zwei Wassermolekülen. Die Hälfte der Natriumionen besetzt Pseudoinversionszentren zwischen den Doppelschichten und befindet sich in oktaedrischer (O6)‐Umgebung zwischen vier Anionen und zwei Wassermolekülen, während die übrigen Natriumionen im Inneren der Doppelschichten intercaliert sind und durch Bindungen zu vier Anionen und zum Wassermolekül des [Cs—H2O—Cs]‐Motivs eine quadratisch‐pyramidale (O5)‐Koordinationssphäre mit Pseudo‐C2‐Symmetrie erreichen. Im Endeffekt verklammert jedes Anion zwei Cs+‐ und zwei Na+‐Ionen, zwei Wassermoleküle bilden [Cs—H2O—Na]‐Motive, das dritte wirkt als μ3‐Brückenligand zwischen zwei Cs+‐Ionen und einem Na+‐Ion. Die Kristallkohäsion wird unterstützt durch ein dreidimensionales Netzwerk von konventionellen (O—H···O=S)‐ und schwachen (C—H···O=S/N)‐Wasserstoffbrücken.
Crystal Structures and Thermal Behaviour of Lanthanide(III) Hexanoate 1, 10‐Phenanthroline Complexes, [M(C5H11CO2)3(phen)] and [Tm(C5H11CO2)2(NO3)(phen)]
Authors: Jongen Liesbet , Bromant Claudia , Hinz‐Hübner Dirk , Meyer Gerd , Robeyns Koen , Van Hecke Kristof , Van Meervelt Luc , Binnemans Koen
Published: May 2003

Lanthanide(III) hexanoate 1, 10‐phenanthroline complexes crystallise in the space group P21/n. The compounds consist of dimers, whereby two lanthanide ions are held together by two bidentate bridging and two tridentate bridging carboxylate groups. The first coordination sphere of the lanthanide ions is completed by one bidentate chelating carboxylate group and by one bidentate 1, 10‐phenanthroline molecule, resulting in the coordination number 9. The dimers have a spherical form, which has important consequences for the thermal properties of complexes. The basic idea behind the preparation of this type of compounds is the stabilisation of the ionic lanthanide layer, so that the smaller lanthanide ions (from which the normal alkanoates do not show mesomorphism because they are too small) show liquid crystallinity. The stabilisation of the ionic layer was successful, expressed by the high melting temperatures, but mesomorphism is not observed. The absence of mesomorphism is related to the isotropic structure of the compounds. A lower symmetry is obtained when a hexanoate group is replaced by a nitrate group. Thulium(III) dihexanoate nitrate 1, 10‐phenanthroline crystallises in the space group P1¯. However, this compound also shows a spherical dimeric structure, but no mesomorphism.
A New Oxynitride Compound of Molybdenum, Na3MoO3N — Synthesis via the Azide Route and Structure
Authors: Arumugam Nachiappan , Hönnerscheid Andreas , Jansen Martin
Published: May 2003

The new oxynitride compound of molybdenum, Na3MoO3N was prepared via the azide route. Its crystal structure was solved and refined from X‐ray powder data (orthorhombic, Pmn21, a = 724.63(1), b = 624.98(1), c = 563.86(1) pm, Rp: 9.04 %; Rwp: 9.83 %). The structure consists of isolated [MoO3N]3— tetra‐hedra which are separated by Na+ cations, also in a tetrahedral coordination. It is isostructural to Na3WO3N which is a lower symmetry derivative of the Cu3AsS4 structure. Due to the small difference in the scattering lengths of nitrogen and oxygen, we were unable to distinguish between fully ordered, fully disordered, or partially ordered anions. However, from the positive SHG responses, we can deduce the acentric space group being the correct one and based on the lattice energy calculations, we have been able to identify the position most probably being occupied by nitrogen.
Synthesis and Structure of a 2, 8, 9‐Trioxa‐3, 5, 7‐trisila‐1‐titanaadamantane
Authors: Arnason Ingvar , Gudnason Palmar I. , Fenske Dieter
Published: May 2003

The title compound has been prepared from [Ti(η5‐C5Me5)Cl3] and cis‐cis‐(t‐BuSi(OH)—CH2)3 in hexane solution in the presence of Et3N. The pale yellow complex was characterized by NMR and MS spectra, as well as by a crystal structure determination. The two crystallographic independent molecules in the triclinic unit cell (space group P1¯, No. 2, Z = 4) both have a nearly identical adamantane‐like TiO3Si3C3 cage of approximate C3v symmetry. The exocyclic C—C—C bond angles in the Cp‐ligand range from 123° to 129°. A quantum chemical calculation of the free molecule predicts this range to be 124° to 127°. The arrangement of the molecules in the crystal is characteristic for an offset face‐to‐face ππ stacking of the aromatic η5‐C5Me5 rings.
Nd4N2Se3 und Tb4N2Se3: Zwei nicht‐isotype Lanthanoid(III)‐Nitridselenide
Authors: Lissner Falk , Schleid Thomas
Published: May 2003

Die nicht‐isotypen Nitridselenide M4N2Se3 des Neodyms (Nd4N2Se3) und Terbiums (Tb4N2Se3) bilden sich durch Umsetzung des betreffenden Selten‐Erd‐Metalls mit Natriumazid (NaN3), Selen und dem entsprechenden Selten‐Erd‐Tribromid (MBr3) nach sieben Tagen bei 900 °C in evakuierten Kieselglasampullen. Sie kristallisieren jeweils monoklin in der Raumgruppe C2/c mit Z = 4 für Nd4N2Se3 (a = 1300, 47(4), b = 1009, 90(3), c = 643, 33(2) pm, β = 90, 039(2)°) bzw. in der Raumgruppe C2/m mit Z = 2 für Tb4N2Se3 (a = 1333, 56(5), b = 394, 30(2), c = 1034, 37(4) pm, β = 130, 377(2)°). Die Kristallstrukturen unterscheiden sich grundlegend in der Verknüpfung der strukturdominierenden N3‐‐zentrierten (M3+)4‐Tetraeder. In Nd4N2Se3 sind die [NNd4]‐Einheiten zu Tetraederdoppeln kantenverknüpft, die über ihre verbleibenden vier Ecken zu Schichten [N(Nd1)(Nd2)]3+ zusammentreten, wohingegen die [NTb4]‐Tetraeder in Tb4N2Se3 durch cis‐Kantenverknüpfung zu Strängen [N(Tb1)(Tb2)]3+ kondensiert vorliegen. Beide Kristallstrukturen enthalten jeweils zwei kristallographisch unterschiedliche M3+‐Kationen, die Koordinationszahlen von sechs und sieben (Nd4N2Se3) bzw. von zweimal sechs (Tb4N2Se3) gegenüber den Anionen (N3‐ und Se2‐) aufweisen. Jeweils zwei unabhängige Sorten von Se2‐‐Anionen sorgen schließlich für die dreidimensionale Vernetzung und den Ladungsausgleich. Wegen des besonderen Achsverhältnisses a/c und des überstumpfen monoklinen Winkels ergeben sich für die Festlegung der Elementarzelle von Tb4N2Se3 zwei Auswahlmöglichkeiten.
New Rhenium(V) Nitrofuryl Semicarbazone Complexes.Crystal Structure of [ReOCl2(PPh3)(3‐(5‐Nitrofuryl)acroleine semicarbazone)]
Authors: Otero L. , Noblia P. , Gambino D. , Cerecetto H. , González M. , Sánchez‐Delgado R. , Castellano E.E. , Piro O. E.
Published: May 2003

The synthesis and characterization of the first two Re complexes with semicarbazone ligands is presented. Selected ligands are 5‐Nitro‐2‐furaldehyde semicarbazone (Nitrofurazone) (L1) and its derivative 3‐(5‐Nitrofuryl)acroleine semicarbazone (L2). Complexes of general formula [ReVOCl2(PPh3)L], where L = L1 and L2, were prepared in good yields and high purity by reaction of [ReVOCl3(PPh3)2] with L in ethanol or methanol solutions. The complexes formula and molecular structures were supported by elemental analyses and electronic, FTIR, 1H, 13C and 31P NMR spectroscopies. In addition, the crystal and molecular structure of [ReVOCl2(PPh3)L2] was determined by X‐ray diffraction methods. [ReOCl2(PPh3)(3‐(5‐Nitrofuryl)acroleine semicarbazone)] crystallizes in the space group P‐1 with a = 11.2334(2), b = 11.3040(2), c = 12.5040(2) Å, α = 81.861(1), β = 63.555(1), γ = 83.626(1)°, and Z = 2. The Re(V) ion is in a distorted octahedral environment, equatorially coordinated to a deprotonated semicarbazone molecule acting as a bidentate ligand through its carbonylic oxygen and azomethynic nitrogen atoms, to an oxo ligand and a chlorine atom. The six‐fold coordination is completed by another chlorine atom and a triphenylphosphine ligand at the axial positions.
Trifluoromethylselenate(0), [SeCF3]—, and Trifluoromethyltellurate(0), [TeCF3]— — Crystalline Products of the Reduction of the Bis(trifluoromethyl)dichalkogen Compounds, E2(CF3)2 (E = Se, Te), with Tetrakis(dimethylamino)ethene (TDAE)
Authors: Tyrra Wieland , Naumann Dieter , Pohl Herbert , Pantenburg Ingo
Published: May 2003

[Bis(dimethylamino)ethanediylidene]bis(dimethylammonium) bis(trifluoromethylchalcogenates(0)), (TDAE)[ECF3]2 (E = Se, Te), are quantitatively formed from the reductions of E2(CF3)2 with tetrakis(dimethylamino)ethene, TDAE. Both compounds are bright yellow to orange solids which crystallize isostructurally with the corresponding sulfur derivative in the orthorhombic space group Pbca (No. 61).

(TDAE)[SeCF3]2 has alternatively been prepared by cation exchange from [NMe4]SeCF3 and (TDAE)Br2.
π‐Facial Selectivity in the Formation of Tricarbonylchromium(0) Complexes of Estra‐1, 3, 5(10), 6‐tetraenes
Authors: Dongol Krishna Gopal , Melo e Silva M. Cristina , Matsubara Kouki , Matsumoto Taisuke , Mataka Shuntaro , Thiemann Thies
Published: May 2003

The preparation of two η6‐estra‐1, 3, 5(10), 6‐tetraene tricarbonylchromium complexes 4 and 6 are described. In both cases only one stereoisomer can be isolated, in contrast to other estrane‐tricarbonylchromium complexes, where complexations are non‐stereoselective. X‐ray crystal structural analysis of 4 discloses that only the more sterically hindered β‐facial isomer is formed. It is assumed that the 6, 7‐olefinic moiety exerts a directive influence on the complexation.
Synthese und Kristallstruktur von [N(Hex)4][Cu2(CN)3]
Authors: Pretsch Thorsten , Brüdgam Irene , Hartl Hans
Published: May 2003

Synthesis and Crystal Structure of [N(Hex)4][Cu2(CN)3]

[N(Hex)4][Cu2(CN)3] has been prepared by solvothermal reaction of CuCN with Tetra‐n‐hexylammoniumiodide in acetone. The crystal structure is built up by condensed (CuCN)6 and (CuCN)7 rings, forming a zeolith type cyanocuprate(I) framework [Cu2(CN)3—]. Space group R3; α = 44.482(6), c = 21.283(4) Å, V = 36471(9) Å3; Z = 9.
Synthesis, Crystal Structure and Properties of [Mn(hdpa)2(N(CN)2)2] and [Co(hdpa)2(N(CN)2)2] (hdpa = 2, 2'‐Dipyridylamine)
Authors: Xu Jing‐Yuan , Bian He‐Dong , Wang Qing‐Lun , Gu Wen , Yan Shi‐Ping , Liao Dai‐Zheng , Cheng Peng , Jiang Zong‐Hui , Shen Pan‐Wen
Published: May 2003

Two new transition metal(II) complexes [M(hdpa)2(N(CN)2)2] (M = Mn (1), Co (2); hdpa = 2, 2'‐dipyridylamine) have been prepared and characterized structurally and magnetically. Both compounds crystallize in the monoclinic space group C2/c. 1 and 2 are isotypic with the unit cell parameters a = 8.634(9), b = 13.541(14), c = 21.99(2) Å, β = 94.806(18)°, and V = 2562(5) Å3 for 1, a = 8.617(3) Å, b = 13.629(5)Å, c = 21.598(8)Å, β = 94.593(6)°, and V = 2528.4(15)Å3 for 2, and Z = 4 for both. According to X‐ray crystallographic studies, each metal(II) ion was six‐coordinated with four nitrogen atoms from two bidentate hdpa ligand and two nitrogen atoms from two N(CN)— anions to form slightly distorted octahedrons. Adjacent complex molecules are connected by hydrogen bonds or π···π interactions to form three‐dimensional network. The IR and UV spectroscopy were measured and the magnetic behaviors were investigated.
Synthese, Struktur und Phasenumwandlung von Te4[AsF6]2·SO2
Authors: Beck Johannes , Steden Folker , Reich Andreas , Fölsing Holger
Published: May 2003

Durch Oxidation von Tellur mit AsF5 in flüssigem SO2 entsteht Te42+[AsF6—]2, das als SO2‐Solvat in Form dunkelroter Kristalle aus der Lösung gewonnen werden kann. Die Kristalle sind sehr empfindlich gegen Luft und gegen Verlust von SO2, weshalb sie nur unter SO2‐Atmosphäre oder unter Kühlung gehandhabt werden können. Die Kristallstruktur wurde bei Raumtemperatur, bei 153 K und bei 98 K bestimmt. Oberhalb von 127 K liegt Te4[AsF6]2 · SO2 in einer orthorhombischen Struktur vor (Pnma, a = 899, 2 (1), b = 978, 79 (6), c = 1871, 61 (1) pm, V = 1647, 13 (2) · 106 pm3 bei 297 K, Z = 4). Die Struktur ist aus quadratisch‐planaren Te42+‐Ionen (Te‐Te 266 pm), oktaedrischen [AsF6]—‐Ionen und SO2‐Molekülen aufgebaut, die über die Sauerstoffatome an die Te4‐Ringe in kantenüberbrückender Position koordinieren. Eines der beiden kristallographisch unabhängigen [AsF6]—‐Ionen zeigt bei Raumtemperatur eine Rotationsfehlordnung, die sich auch bei Abkühlung auf 153 K nicht vollständig ausordnet. Bei 127 K durchläuft Te4[AsF6]2 · SO2 eine Phasenumwandlung in eine monokline Struktur (P1121/a, a = 866, 17(8), b = 983, 93(5), c = 1860, 10(6) pm, γ = 96, 36(2)°, V = 1554, 2(2) · 106 pm3 bei 98 K, Z = 4). In der Tieftemperaturphase liegen alle [AsF6]—‐Ionen geordnet vor. Obwohl eine direkte Obergruppe‐Untergruppe‐Beziehung zwischen den Raumgruppen vorliegt, verläuft der Phasenübergang nach der ersten Ordnung mit sprunghaften λnderungen der Gitterparameter. Der Phasenübergang ist von einer Zwillingsbildung begleitet. Der wesentliche Unterschied in der Struktur der Tieftemperaturphase im Vergleich zur Raumtemperatur liegt in einer veränderten Koordination des Te42+‐Ions durch O‐ und F‐Atome benachbarter SO2‐ und [AsF6]—‐Moleküle.
Silver Complexes with Cyanoguanidine: Preparation and Crystal Structures of [Ag(cgn)2]F and [Ag(cgn)2][BF4]
Authors: Bessler Karl Eberhard , Torres de Sousa Adriana , Deflon Victor Marcelo , Niquet Elke
Published: May 2003

The silver cyanoguanidine complexes [Ag(cgn)2]F (1), [Ag(cgn)2][BF4] (2), [Ag(cgn)2][ClO4] (3) and [Ag(cgn)][NO3] (4) were obtained from aqueous solutions of the corresponding silver salts and cyanoguanidine. The crystal structures of 1 and 2 have been determined by single crystal X‐ray diffraction.

1: Space group P1¯, Z = 2, cell constants at —65 °C: a =618.18(3), b = 761.49(8), c = 971.2(1) pm; α = 93.56(1), β = 97.439(8), γ = 97.376(9)β; R1 = 0.0218

2: Space group P1¯, Z = 2, cell constants at —65 °C: a = 549.79(9), b = 958.17(17), c = 1121.04(12) pm; α = 90.026(13), β = 102.520(11), γ = 95.937(14)°; R1 = 0.0283.
Synthese und Kristallstruktur von [(Me3Si)2BiCu(PMe3)3], dem ersten Komplex mit einer Bismut—Kupfer‐Bindung
Authors: Fenske Dieter , Rothenberger Alexander , Wieber Stephan
Published: May 2003

Synthesis and Crystal Structure of [(Me3Si)2BiCu(PMe3)3] — the First Complex with a Bismuth—Copper Bond

The reaction of CuOt Bu with PMe3 and Bi(SiMe3)3 in hexane yields the phosphine‐stabilized complex [(Me3Si)2Bi‐Cu( PMe3)3]. This synthesis gave rise to the first binuclear Bi—Cu compound to be structurally characterized by X‐ray crystallography.
Synthesis, Structure and Reactivity of PH‐Phosphoraneiminato‐ and Iminophosphoraneiminato Group 4 Transition‐Metal Complexes
Authors: Raab Michael , Tirreé Jürgen , Nieger Martin , Niecke Edgar
Published: May 2003

The versatile coordination chemistry of the well‐investigated phosphoraneiminato‐ligand R3PN— (I) was extended by the successive introduction of protons to the phosphorus atom. The position of the resulting equilibrium between the NH‐phosphanylamido‐ [R2P‐NH—] and the PH‐phosphoraneiminato‐form [R2HP=N—] is affected by the Lewis acidity of the coordinated metal fragment. Experimental studies on complexes with various substitution patterns at the group 4 metal center R2HP=N[M] (II) were unambiguously confirmed by DFT‐calculations. The isolation of group 4 PH‐dihydrido‐phosphoraneiminato‐complexes RH2P‐N[M] (III) is prevented by the low thermodynamic stability of the target molecules, also supported by the results of ab initio calculations. However, an access to the by then unknown transition‐metal substituted iminophosphanes RP=N[M] (IV) was verified for the first time.

Within extensive studies on the coordination chemistry of bis(imino)phosphoranes RP(=NR′)(=NR″), several species of group 4 complexes R(R′N=)P=N[M] (V) were isolated and structurally characterized. In this case, investigations on the NH/PH‐tautomerism were performed exclusively on theoretical level, because the required educts are experimentally non‐accessible due to their kinetic instability.
Theoretical Studies of Inorganic Compounds. 27 Quantum Chemical Investigations of Transition Metal Nitrido Complexes with a TM‐N‐E Linkage (E = Main Group Element)
Authors: Spuhler Philipp , Lein Matthias , Frenking Gernot
Published: May 2003

It is reported about quantum chemical DFT calculations of various transition metal (TM) nitrido complexes which contain a TM‐N‐E linkage. The goal is to elucidate the nature of the TM‐N‐E bonding situation with modern quantum chemical tools. Five comparative investigations have been carried out. (a) Comparison of the N‐donor ability in the nitrido complexes Cl3W‐N‐ECln where ECln = NaCl, MgCl2, AlCl3. (b) Comparative analysis of the bonding situation in Cl4W‐N‐X where X = Na, MgCl, AlCl2, SiCl3, PCl2, SCl, Cl. (c) Comparison of the structure and bonding in Cl5W‐NPH3, Cl5W‐OPH3+, Cl4W‐(NPH3)(OPH3)+. (d) Comparative analysis of the bonding situation in Cl5Ta‐OPH3, Cl5W‐NPH3, Cl5Re‐CPH3. (e) Energy decomposition analysis of the bonding of the isolobal ligands NPH3 and Cp with WCl5.