scholarly journals Structural isomerism in the [(Ni@Sn9)In(Ni@Sn9)]5− Zintl ion

2019 ◽  
Vol 48 (42) ◽  
pp. 15888-15895
Author(s):  
Chao Zhang ◽  
Harry W. T. Morgan ◽  
Zi-Chuan Wang ◽  
Chao Liu ◽  
Zhong-Ming Sun ◽  
...  
Keyword(s):  
The Other ◽  
Indium Atom ◽  
Structural Isomerism ◽  
Zintl Ion

A new Zintl cluster, [(Ni@Sn9)In(Ni@Sn9)]5−, has been isolated in two distinct isomeric forms, one where both Ni@Sn9 units are coordinated to the bridging indium atom in an η3- mode, the other where one is η3- and the other η4-.

Synthesis and structural studies of iron(II) and iron(III) sulfonates

1981 ◽  
Vol 59 (4) ◽  
pp. 669-678 ◽  
Author(s):  
John S. Haynes ◽  
John R. Sams ◽  
Robert C. Thompson
Keyword(s):  
Electronic Spectra ◽  
Lattice Structure ◽  
Magnetic Moments ◽  
The Other ◽  
Antiferromagnetic Coupling ◽  
Structural Studies ◽  
Structural Isomerism ◽  
Mössbauer Data

The iron(II) sulfonates Fe(CF3SO3)2 and Fe(p-CH3C6H4SO3)2 have been prepared and on the basis of vibrational and electronic spectra and magnetic and MÖssbauer data have been assigned a layer lattice structure involving hexacoordinated iron(II) and terdentate bridging anions. The FeO6 chromophore in these compounds is distorted by a trigonal elongation along the C3 axis. Fe(CH3SO3)2 has been obtained in two isomeric forms, one having a trigonal elongation of the FeO6 chromophore, the other a trigonal compression. No structural isomerism has been found for the other iron(II) sulfonates; however, evidence for such isomerism in methanesulfonates of cobalt(II) and zinc(II) is presented. While Fe(CF3SO3)2 and Fe(p-CH3C6H4SO3)2 appear to be magnetically dilute the presence of antiferromagnetic coupling in both forms of Fe(CH3SO3)2 is indicated. The iron(III) sulfonates, Fe(CF3SO3)3, Fe(p-CH3C6H4SO3)3, and Fe(CH3SO3)3, have been prepared and all three are magnetically concentrated exhibiting magnetic moments which are significantly less than 5.92 BM and which decrease with decreasing temperature.

A PPP-investigation of Structural Isomerism in Infinite Polyenes

1982 ◽  
Vol 37 (1) ◽  
pp. 28-32 ◽  
Author(s):  
Peter Karadakov ◽  
Obis Castaño
Keyword(s):  
Bond Order ◽  
Analytical Form ◽  
The Other ◽  
Nearest Neighbour ◽  
Bond Orders ◽  
Coulomb Interactions ◽  
Hartree Fock ◽  
Structural Isomerism ◽  
Bond Alternation ◽  
Self Consistent

Abstract It is shown on the grounds of a semiempirical PPP-treatment that for the equidistant eistrans infinite polyene two types of Hartree-Fock solutions are possible-one yielding a cis-transoid and the other a trans-cisoid distribution of nearest-neighbour bond-orders. Relaxing the nuclear framework according to bond-order magnitudes for the bond-alternation wave (BAW) in the equidistant all-trans polyene, resp. for the two solutions for the equidistant cis-trans polyene mentioned above and using repeatedly the Coulson-Golebiewski formula, realistic self-consistent values of bond lengths have been obtained. The calculated energy differences between the investigated isomers are small, predicting almost equal probabilities. The expressions for the PPPwavefunctions are presented in analytical form suitable for further applications. Long-range Coulomb interactions have been accounted for up to convergence of the groundstate energies.

scholarly journals Carbonyl Chalcogenides Clusters Existing as Disguised Forms of Hydrocarbon Isomers

2016 ◽  
Vol 8 (3) ◽  
pp. 35
Author(s):  
Enos Masheija Rwantale Kiremire
Keyword(s):  
Metal Carbonyl ◽  
Structural Similarity ◽  
Borderline Case ◽  
The Other ◽  
Series Method ◽  
Ion Clusters ◽  
Chalcogenide Clusters ◽  
Wide Range ◽  
Zintl Ion ◽  
Equivalent Carbon

<p>The 4n Series Method has been utilized to categorize, analyze and predict structures for transition metal carbonyl, borane, hydrocarbon and Zintl ion clusters. The method is being extended to study carbonyl chalcogenide clusters. Adequate examples have been given to demonstrate the application of the 4n series method to categorize clusters and where possible predict their possible skeletal structures. In this paper, the method is being applied to the study of carbonyl chalcogenide cluster complexes. What has been found is the striking structural similarity of a wide range of carbonyl chalcogenide clusters to those of corresponding hydrocarbon clusters. It was observed that when a derived hydrocarbon from a cluster, F<sub>CH</sub> = C<sub>n</sub>H<sub>q</sub>, is such that n&lt;q, the cluster portrays structural similarity with an equivalent hydrocarbon. On the other hand when n&gt;q, the ‘hydrocarbon character’ becomes reduced and the typical cluster tendencies increase. When n = q, the situation becomes more or less a borderline case. When q=0, then F<sub>CH</sub> = C<sub>n</sub>. When the series becomes bi-capped or more, then the equivalent carbon cations are obtained.</p>

CHROMOSOMAL POLYMORPHISM IN NORTH AMERICAN PISSODES WEEVILS: STRUCTURAL ISOMERISM

1970 ◽  
Vol 12 (3) ◽  
pp. 506-540 ◽  
Author(s):  
Stanley G. Smith
Keyword(s):  
Introgressive Hybridization ◽  
Chromosomal Polymorphism ◽  
The Other ◽  
Length Frequency ◽  
Structural Isomerism ◽  
Hybrid Complex ◽  
Different Types ◽  
Random Assortment ◽  
Isolating Mechanism ◽  
Frequency Basis

Pissodes approximatus and P. canadensis, two taxa named by Hopkins, are shown to constitute a hybrid complex that forms a numerical-morphological karyocline between the southeast of North America and the Yukon. The two A metacentrics and the two B submetacentrics in the SE (predominantly 2n = 30) are each sequentially replaced by twin acrocentrics, aa and bb, in the NW (mainly 2n = 34). The two b pairs, of markedly different length, are segmentally interchanged in the SE relative to those in the NW, the distal interchanged segments being equal. The two Bs, derived by fusion of alternative acrocentrics, simulate pericentrically inverted, complementary submetacentrics. Introgression of the four structurally different types, commonest at the centre of the karyocline, results in 10 distinct B: bb karyotypes of which only 6 appear different; the other 4 are mirror images, or isomers.The intermediate karyotypes have been synthesized by crossing different AB and aabb taxa; they implicate two pairs of isomeric species in the origin of the polymorphic complex. Of these, one AB species with 'standard' Bs and two aabb species with relatively interchanged bs are extant. The fourth, a species with inverted Bs, may be extinct, have merely escaped detection, or else is completely introgressed.Chiasma formation is near perfect in natural polyisomorphs and almost equally so in synthetics. In fact, in both bb/bb heterozygotes the maximum number of associations per cell, normally 16 (the XY pair is achiasmate), is increased by the formation of anomalous quadruple configurations resulting from extra unions at the centric ends of the bs. If chiasmate and situated in minute arms, these unions far exceed expectation on a length-frequency basis, for such arms cannot be resolved in colchicined gonial metaphases. Whether the extra unions are truly chiasmate, as believed, or not, they nevertheless greatly influence the first metaphase disjunctional arrangement of the multiples and cause production of about 80% unbalanced gametes vs. the 50% expected of random assortment, thus generating a genetic isolating mechanism. Such acrocentric heterozygotes, though carrying a heavy segregational-sterility load, persist by recurrent SE-NW introgressive hybridization.

Stromatoporoids from the Famennian (Devonian) Wabamun Formation, Normandville oilfield, north–central Alberta, Canada

1988 ◽  
Vol 62 (03) ◽  
pp. 411-419 ◽  
Author(s):  
Colin W. Stearn
Keyword(s):  
Patch Reef ◽  
Abundant Species ◽  
The Other ◽  
North Central ◽  
Biotic Crisis

Stromatoporoids are the principal framebuilding organisms in the patch reef that is part of the reservoir of the Normandville field. The reef is 10 m thick and 1.5 km2in area and demonstrates that stromatoporoids retained their ability to build reefal edifices into Famennian time despite the biotic crisis at the close of Frasnian time. The fauna is dominated by labechiids but includes three non-labechiid species. The most abundant species isStylostroma sinense(Dong) butLabechia palliseriStearn is also common. Both these species are highly variable and are described in terms of multiple phases that occur in a single skeleton. The other species described areClathrostromacf.C. jukkenseYavorsky,Gerronostromasp. (a columnar species), andStromatoporasp. The fauna belongs in Famennian/Strunian assemblage 2 as defined by Stearn et al. (1988).

D. The Line Spectrum of Pulsating Variable Stars

1967 ◽  
Vol 28 ◽  
pp. 207-244
Author(s):  
R. P. Kraft
Keyword(s):  
Variable Stars ◽  
The Other ◽  
Line Spectrum ◽  
Afternoon Session ◽  
Empirical Information ◽  
Pulsating Variable Stars ◽  
Almost Continuous ◽  
Informal Approach

(Ed. note:Encouraged by the success of the more informal approach in Christy's presentation, we tried an even more extreme experiment in this session, I-D. In essence, Kraft held the floor continuously all morning, and for the hour and a half afternoon session, serving as a combined Summary-Introductory speaker and a marathon-moderator of a running discussion on the line spectrum of cepheids. There was almost continuous interruption of his presentation; and most points raised from the floor were followed through in detail, no matter how digressive to the main presentation. This approach turned out to be much too extreme. It is wearing on the speaker, and the other members of the symposium feel more like an audience and less like participants in a dissective discussion. Because Kraft presented a compendious collection of empirical information, and, based on it, an exceedingly novel series of suggestions on the cepheid problem, these defects were probably aggravated by the first and alleviated by the second. I am much indebted to Kraft for working with me on a preliminary editing, to try to delete the side-excursions and to retain coherence about the main points. As usual, however, all responsibility for defects in final editing is wholly my own.)

C. The Continuous Spectrum of Pulsating Variable Stars

1967 ◽  
Vol 28 ◽  
pp. 177-206
Author(s):  
J. B. Oke ◽  
C. A. Whitney
Keyword(s):  
Continuous Spectrum ◽  
Variable Stars ◽  
Velocity Fields ◽  
The Other ◽  
Line Spectrum ◽  
Direct Information ◽  
Thermodynamic Structure ◽  
Diagnostic Interpretation ◽  
Pulsating Variable Stars ◽  
The Continuum

Pecker:The topic to be considered today is the continuous spectrum of certain stars, whose variability we attribute to a pulsation of some part of their structure. Obviously, this continuous spectrum provides a test of the pulsation theory to the extent that the continuum is completely and accurately observed and that we can analyse it to infer the structure of the star producing it. The continuum is one of the two possible spectral observations; the other is the line spectrum. It is obvious that from studies of the continuum alone, we obtain no direct information on the velocity fields in the star. We obtain information only on the thermodynamic structure of the photospheric layers of these stars–the photospheric layers being defined as those from which the observed continuum directly arises. So the problems arising in a study of the continuum are of two general kinds: completeness of observation, and adequacy of diagnostic interpretation. I will make a few comments on these, then turn the meeting over to Oke and Whitney.

Observing programme for the 24-inch/36-inch Schmidt telescope

1966 ◽  
Vol 24 ◽  
pp. 337
Author(s):  
W. Iwanowska
Keyword(s):  
The Other ◽  
Schmidt Telescope ◽  
Flint Glass

A new 24-inch/36-inch//3 Schmidt telescope, made by C. Zeiss, Jena, has been installed since 30 August 1962, at the N. Copernicus University Observatory in Toruń. It is equipped with two objective prisms, used separately, one of crown the other of flint glass, each of 5° refracting angle, giving dispersions of 560Å/mm and 250Å/ mm respectively.

A hard choice for Tomasello

2020 ◽  
Vol 43 ◽  
Author(s):  
Philip Pettit
Keyword(s):  
Joint Action ◽  
The Other ◽  
Hard Choice ◽  
Margaret Gilbert ◽  
Michael Bratman ◽  
Human Sense ◽  
Sense Of Obligation

Abstract Michael Tomasello explains the human sense of obligation by the role it plays in negotiating practices of acting jointly and the commitments they underwrite. He draws in his work on two models of joint action, one from Michael Bratman, the other from Margaret Gilbert. But Bratman's makes the explanation too difficult to succeed, and Gilbert's makes it too easy.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

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