α-K_3H_4[SiW_9Al_3(H_2O)_3O_(37)]·7H_2O的晶体结构

三取代杂多化合物的母体XM_9是由Keggin结构阴离子XM_(12)衍生而来.它有2种异构体:从XM_(12)中移出1个M_3O_(13)基团得B型异构体;从XM_(12)中的3个M_3O_(13)中各移出1个MO_6后得到A型异构体.Hervé等人曾指出α-和β-SiW_9均为B型结构,但Robert等在测定β-Na_9H(SiW_9O_(34))·23H_2O的晶体结构时发现,β-SiW_9为A型结构,α-SiW_9结构类型尚未定论,由于2种构型阴离子的配位能力及聚合能力不同,确定其结构类型及其变化情况是十分必要的,本文由α-SiW_9合成了α-K_3H_4[SiW_9A1_3(H_2O)_3O_(37)],用X射线衍射法测定了其晶体结构。     

A generalized wreath product method for the enumeration of stereo and position isomers of polysubstituted organic compounds

Ageneralized wreath product group is developed in the root-to-root product formalism for the enumeration of stereo and position isomers of polysubstituted organic compounds. The methods expounded here are used for enumerating the NMR signals of polysubstituted organic compounds.     

四种同分异构的四环稠环芳烃的激光等离子体质谱分析

在常规质谱中,各种同分异构的稠环芳香烃基本上无法分辨。但在本文报道的以近红外脉冲激光所产生的等离子体质谱中,所分析的四个四稠环芳香烃尽管分子量相同,其负离子质谱却有十分明显的差异,显示了这一研究方法的结构鉴别能力。     

Isomers of polycyclic conjugated hydrocarbons with six-membered and seven-membered rings

Summary Monoheptapolyhexes are polygonal systems with exactly one heptagon and otherwise hexagons. General formulations with emphasis on the C _n H _s formula, and the first enumerations of C _n H _s isomers are reported for these systems. Also a more general class of systems is treated in some detail, viz. P₇₍₆₎, which consists of hexagons and/or heptagons. The maximum numbers of heptagons for given C _n H _s formulas are studied, and the possible C _n H _s formulas are specified.

---

Isomere von polycyclischen konjugierten Kohlenwasserstoffen mit 6- und 7-gliedrigen Ringen

Zusammenfassung Monoheptapolyhexe sind polygonale Systeme mit genau einem Siebeneck und ansonsten nur Sechsecken. Es wird der allgemeine Formelapparat mit Betonung auf C _n H _s und die Auswertung bezüglich der Anzahl von C _n H _s -Isomeren für diese Systeme berichtet. Ebenso wird über eine generellere Klasse von Systemen, nämlich P₇₍₆₎ berichtet, die aus Sechsecken und/oder Siebenecken besteht. Die Maximalanzahl von Siebenecken für gegebene C _n H _s -Formeln wird untersucht und mögliche C _n H _s -Formeln werden angegeben.

     

Graphs to chemical structures 3. General theorems with the use of different sets of sphericity indices for combinatorial enumeration of nonrigid stereoisomers

The extended sphericity indices of k-cycles, which were defined in Part 2 of this series (S. Fujita, Theor Chem Acc, Online: http://www.springerlink.com/index/10.1007/s00214-004-0606-z) according to the enantiospheric, homospheric, or hemispheric nature of each k-cycle, are further extended to prove more general theorems for enumerating nonrigid stereoisomers with rotatable ligands. One of the extended points is the use of different sets of sphericity indices to treat one or more orbits contained in skeletons and ligands. Another is to take account of chirality in proligands and sub-proligands, the latter of which are introduced to consider further inner structures of ligands. Two theorems for enumerating nonrigid stereoisomers are proved by adopting two schemes of their derivation, i.e., the scheme ``positions of a skeleton ⇐ proligands ⇐ ligands (positions of a ligand ⇐ sub-proligands)' and the scheme ``(positions of a skeleton ⇐ proligands ⇐ ligands (positions of a ligand)) ⇐ sub-proligands'. The theorems are applied to the stereoisomerism of trihydroxyglutaric acids. Thereby, it is demonstrated where Pólya's theorem and other previous methods are deficient, when applied to the enumeration of stereoisomers.     

Ab Initio Studies on the [Os(PR_3)_4H(H_2)]~+ System

The [Os(PH3)4H(H2)]+ system was studied using the Gaussian 88 and the energy gradient technique at the restricted Hartree-Fock level under the effective core potential (ECP) approximation. The two different isomers of complex [Os(PH3)4H (H2)] (cis and trans) were optimized, and several orientations of the hydrogen molecule were considered for the cis isomer. When the hydride is placed in the cis position and oriented suitably, there is a strongly attractive effect between it and the molecular hydrogen.     

开链单烯和开链单炔的同卤代物的异构体计数

将Polya计数定理用于求开链单烯和开链单炔被同种卤素取代的取代物的各种异构体计数母函数,同时讨论了被同种卤素取代的单环烯烃同系物和由4种卤素取代的单烯和单炔的各种异构体计数母函数的求法。     

Quantitation of isomeric ethyl pyridine mixtures by multivariate calibration applied to ion-molecule reaction/collision-induced dissociation triple-stage mass spectra

In reactions of the distonic ion ⁺CH₂OCH₂ with the three isomeric ethyl pyridines, ionized methylene transfer occurs readily yielding distonic N-methylene-ethylpyridinium ions. On-line mass selection and 10 eV collision-induced dissociation (CID) of the CH₂⁺ transfer products yields characteristic fragment ions, which are formed via processes greatly influenced by the ortho, meta or para location of the ethyl substituent in the pyridine ring. Quantitation of mixtures of isomeric 2-, 3-, and 4-ethyl pyridines of varying compositions was then performed by multivariate calibration in the form of the partial least square (PLS) model applied to both single-stage (MS) 70 eV electron ionization (EI) and pentaquadrupole triple-stage sequential ion-molecule reaction/CID product ion mass spectra. The results exemplify the superior ability of combined chemometric analysis and sequential mass spectrometric techniques, which benefits from both characteristic ion chemical reactivity and dissociation behavior, for rapid and accurate quantitation of complex isomeric mixtures.     

Synthesis and Structure of a Novel Supramolecular Compound [Co(2,2''-bipy)(H2 O)4 ][trans-1,4-chdc] and Separation of Isomer of 1,4-Cyclohexanedicarboxylic Acid

A supramolecular compound, [Co(2,2'-bipy)(H2O)4][trans-1,4-chdc] (compound 1) (2,2'-bipy=2,2'-bipyridine, 1,4-chdcH2=1,4-cyclohexanedicarboxylic acid), was synthesized and characterized by single-crystal X-ray diffraction analysis, IR spectrometry, TG analysis, and elemental analyses. Single-crystal X-ray diffraction analysis revealed that [Co(2,2'-bipy)(H2O)4]2 units and adjacent 1,4-chdc2- formed a single layer by hydrogen bonding and electrostatic interactions along the ac-plane, and two symmetry-related single layers interacted with each other by hydrogen bonding, resulting in a double layer, which further formed a 3-D structure by π-π stacking. The most attractive structural feature of compound 1 is that 1,4-chdc2- possesses only trans-conformation although there are both cis- and trans-conformations in the raw material.     

Gas chromatographic behaviour of isomeric tricyclo[10.4.0.04,9]hexadecanes

Summary Using achiral stationary phases of different polarity in capillary gas chromatography it is demonstrated that the hydration of 1,2–5,6-dibenzocycloocta-1,5-diene yields five isomers of the tricyclo[10.4.0.0^4,9]hexadecanes. With highly polar stationary phases all isomers of the tricyclic hexadecanes and the semihydrated products in the mixture were also separated from each other. The chiral isomers were separated on cyclodextrin stationary phase. Moreover, with columns of achiral and chiral phases coupled in series, in a double oven gas chromatograph, it was possible to estimate the configuration of the isomers. The separation of diastereomers on chiral stationary phases is a useful means for structural assignment of isomeric compounds.Dedicated to Professor Leslie S. Ettre on the occasion of his 70th birthday.