scholarly journals IX—investigations on magne-crystallic action III—Further studies on organic crystals

1935 ◽  
Vol 234 (739) ◽  
pp. 265-298 ◽  
Keyword(s):  
Molecular Structure ◽  
Crystal Lattice ◽  
Convenient Method ◽  
Organic Crystals ◽  
Double Refraction ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
Benzene Rings ◽  
The Individual ◽  
Ray Methods

In Part I* of this paper a convenient method of measuring the principal magnetic susceptibilities of single crystals was described, and several organic crystals, among others, were studied by this method. The results were discussed particularly in relation to the structure of the molecules and their orientations in the crystal lattice, and it was shown how a correlation of the principal magnetic susceptibilities of the crystal with those for the individual molecules (obtained from measurements on magnetic double-refraction in the liquid state, or from considerations of molecular structure) gives us useful information regarding the orientations of the molecules in the crystal lattice. Indeed, in favourable cases the molecular orientations may thus be determined much more easily, and some of the parameters defining the orientations also more accurately, than by X-ray methods of analysis. Conversely, where the molecular orientations in the crystal lattice are already known from X-ray studies, a knowledge of the principal magnetic susceptibilities of the crystal enables us to obtain the magnetic constants of the individual molecules, which are of interest. For example, it is thus found that as one proceeds from benzene to naphthalene and from naphthalene to anthracene, the numerical increase in susceptibility that occurs, is directed predominantly along the normal to the plane of the benzene rings

scholarly journals Investigations on magne-crystallic action. Part I.-Diamagnetics

1933 ◽  
Vol 231 (694-706) ◽  
pp. 235-262 ◽  
Keyword(s):  
Magnetic Anisotropy ◽  
Direct Effect ◽  
Liquid State ◽  
Unit Cell ◽  
The Body ◽  
Double Refraction ◽  
X Ray ◽  
Regular Manner ◽  
The Individual ◽  
Ray Methods

It is well known, from the investigations of COTTON and MOUTON and others* on the magnetic double-refraction of liquids, that diamagnetic molecules in general are magnetically anisotropic. When such molecules are arranged in a regular manner as they are in a crystal, the crystal, as a whole, will usually exhibit differences in susceptibility in different directions. The magnitude of these differences will evidently depend on the relative orientations of the molecules in the unit cell; their positions in the cell will have no direct effect, since the diamagnetic moments induced in the molecules are so feeble that their mutual influences are negligible.* Thus a correlation of the magnetic anisotropy of the crystal with that of the individual molecules constituting it, calculated from measurements on magnetic double-refraction in the liquid state, or from other considerations, is likely to give us useful information regarding the orientations of the molecules. This method of analysis of molecular orientations in crystals, which was first suggested by one of us, promises, at any rate, in favourable circumstances, to be a useful supplement to X-ray methods of crystal analysis. Indeed, in certain crystals—as will be seen in the body of the present paper—the molecular orientations can thus be determined more easily and with greater accuracy than by X-ray methods.

Chalkogenolat-Ionen und ihre Derivate, V Kristall- und Molekülstruktur von 2.8-Dimethyldibenzo [c.g] [1.2.5.6] tetrathiacyclooktadien, einem Oxidationsprodukt von 4-Methylbenzol-1.2-dithiol/Chalcogenolates and their Derivatives, V Crystal and Molecular Structure of 2.8-Dimethyldibenzo[c,g][1,2,5,6]tetrathiaocin, an Oxidation Product of 4-Methylbenzene-1,2-dithiol

1979 ◽  
Vol 34 (1) ◽  
pp. 48-51 ◽  
Author(s):  
Jürgen Kopf ◽  
Klaus von Deuten ◽  
Bahman Nakhdjavan ◽  
Günter Klar
Keyword(s):  
Molecular Structure ◽  
Dihedral Angle ◽  
Oxidation Product ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
The Mean ◽  
Ray Methods ◽  
Anti Form

Abstract The structure of 2,8-dimethyldibenzo[c,g][1,2,5,6]tetrathiaocin (1b) has been determined by X-ray methods and discussed in connection with the preferred conformations of diaryl disulfides. The compound has the anti-form I. The SS-distance is 205.8 pm, the mean CSS-angle 104.1°, and the CSS/SSC-dihedral angle 111.1°.

η3- Allymetall-Schwefel-Cluster des Nickels, Palladiums und Platins / η3-Allyl Metal Sulfur Cluster Compounds of Nickel, Palladium, and Platinum

1979 ◽  
Vol 34 (4) ◽  
pp. 609-613 ◽  
Author(s):  
Borislav Bogdanović ◽  
Richard Goddard ◽  
Peter Göttsch ◽  
Carl Krüger ◽  
Klaus Schlichte ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Structural Similarity ◽  
Molecular Data ◽  
Cluster Compounds ◽  
Sulfur Cluster ◽  
Space Group ◽  
X Ray ◽  
Coordination Sites ◽  
Cell Data ◽  
Ray Methods

AbstractNovel cluster compounds of the composition [(η3-C3H5)2M2S]x, wherein M represents nickel, palladium or platinum are obtained by reaction of 2,5-disubstituted-1,6,6a-trithiopentalenes or H2S with (η3-C3H5)2M in THF solution. The molecular structure of one of these new cluster types [(η3-C3H5Ni)2S]3 has been established by X-ray methods. It is best described as being a fraction of a NiS-framework in which peripheral coordination sites are occupied by partial disordered η3-allyl groups. Molecular data (cell data: a = 19.868(4), b = 8.988(2), c = 14.501(3) Å, β = 115.30(2)°, space group C2/c, Z = 4, R = 0.106) are compared with the parent Bs-NiS lattice. Spectroscopic evidence for the structural similarity of the related Pd- and Pt-compounds is given.

A Ring Destruction Approach to Some Benzo-Fused Medium-Sized Heterocycles by Means of Cyanogen-Bromide Under Solvolytic Conditions - X-Ray Structure of a '1h-2,6-Benzoxazecine-6-Carbonitrile and a '2h-3,6-Benzoxazecine-6-Carbonitrile Derivative

1986 ◽  
Vol 39 (6) ◽  
pp. 893 ◽  
Author(s):  
JB Bremner ◽  
CL Raston ◽  
GL Rowbottom ◽  
AH White ◽  
KN Winzenberg
Keyword(s):  
Molecular Structure ◽  
Tertiary Amine ◽  
Cyanogen Bromide ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
Concomitant Reduction ◽  
Heterocyclic Derivatives ◽  
Isoquinoline Derivatives ◽  
Ray Methods ◽  
Medium Ring

Reaction of the reduced pyrrolo [2,1-a] isoquinoline amine (1a) with cyanogen bromide in the presence of methanol gave the medium-ring cyanamide derivative 7,9,10-trimethoxy-2,3,4,5,6,7-hexahydro-1H-3- benzazonine-3-carbonitrile (2a). Analogous products were also obtained from reaction of the reduced 5H-oxazolo[2,3-a] isoquinoline , 2H- benzo [a] quinolizine , 2H,6H-[1,3] oxazino [2,3-a] isoquinoline and [1,4] oxazino [3,4-a] isoquinoline derivatives (1b-e), whereas the reduced 3H-oxazolo[4,3-a] isoquinoline and 5H-oxazolo[2,3-a] isoquinoline derivatives (1f) and (8) gave 1-(2,4-dioxapentyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-2-carbonitrile (5a) and N-[2-(2-benzoyl-4,5-dimethoxyphenyl)ethyl]-N- methylcyanamide (9) respectively, the latter in low yield. The medium-sized heterocyclic derivatives (2f-h) were also obtained from cyanogen -bromide-mediated water solvolysis reactions of (1a), (1c) and (1e). The cyanamides (2a-h), (5a) and (9) have been converted into the respective tertiary amine derivatives (3a- h), (5c) and (11), with concomitant reduction of the carbonyl group in the last case. The crystal and molecular structure of 1,10,11- trimethoxy-3,4,5,6,7,8-hexahydro-1H-2,6-benzoxazecine-6-carbonitrile (2d) and 1-hydroxy-10,11-dimethoxy-1,4,5,6,7,8-hexahydro-2H-3,6- benzoxazecine-6-carbonitrile (2h) have been determined by single- crystal X-ray methods.

Lewis-Säure/Base Addukte von TiCl4 und Methylpyridinen / Lewis Acid/Base Adducts of TiCl4 and Methylpyridines

2000 ◽  
Vol 55 (9) ◽  
pp. 877-881 ◽  
Author(s):  
Karl Hensen ◽  
Alexander Lemke ◽  
Michael Bolte
Keyword(s):  
Molecular Structure ◽  
Lewis Acid ◽  
Equatorial Position ◽  
Acid Base ◽  
Nitrogen Base ◽  
X Ray ◽  
Nitrogen Bases ◽  
Distorted Trigonal Bipyramid ◽  
In Trans ◽  
Ray Methods

By the reaction of 2-methyl- and 2,6-dimethylpyridine the first neutral TiCl4L complexes (L = single bonded ligand) could be synthesized. The structures have been determined by single crystal X-ray methods. The best description of the molecular structure is a distorted trigonal bipyramid with the nitrogen base occupying an equatorial position. With 2,4-dimethylpyridine, a 1:2 adduct is formed, where the nitrogen bases are in trans-positions of a TiCl4N2-octahedron, as also confirmed by an X-ray analysis

Komplexe des Typs [MCl4(SEt2)2] mit M = Mo und W. Kristallstrukturen, NMR-Spektren und magnetisches Verhalten/[MCl4(SEt2)2] Complexes with M = Mo and W. Crystal Structures, NMR Spectra, and Magnetic Behaviour

1995 ◽  
Vol 50 (2) ◽  
pp. 159-167 ◽  
Author(s):  
Peter Dierkes ◽  
Gerlinde Frenzen ◽  
Sigrid Wocadlo ◽  
Werner Massa ◽  
Stefan Berger ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Nmr Spectra ◽  
Magnetic Behaviour ◽  
Triclinic Space Group ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
Metal Atoms ◽  
Ray Methods ◽  
C Nmr

The crystal structures of the thioether complexes [MCl4(SEt2)2] with M = Mo and W have been solved by X-ray methods. Both compounds crystallize isotypically in the triclinic space group P1̄ with two formula units per cell unit. The metal atoms are octahedrally coordinated by four chlorine atoms and by the two sulfur atoms of the thioether molecules in transposition (symmetry Ci) with bond lengths (average): Mo-Cl 233.1, Mo-S 253.4, W-Cl 233.1, and W-S 251.7 pm. Both complexes were also characterized by 1H and 13C NMR spectroscopy as well as by measurement of the magnetic susceptibilities in the temperature range from 1.8 to 350 K.

Solutions of Aluminium Trichloride in Tetramethylurea and the Molecular Structure of an Aluminium Trichloride Tetramethylurea Adduct

1986 ◽  
Vol 41 (5) ◽  
pp. 587-591 ◽  
Author(s):  
Astrid Bittner ◽  
Detlef Männig ◽  
Heinrich Nöth
Keyword(s):  
Molecular Structure ◽  
Nmr Spectroscopy ◽  
Oxygen Atom ◽  
Free Ligand ◽  
Addition Product ◽  
X Ray ◽  
Molecular Adduct ◽  
Aluminium Trichloride ◽  
Ray Methods

Abstract Aluminium trichloride forms a 1:1 addition product with tetramethylurea (1) the structure of which has been determined by X-ray methods. Tetramethylurea is bound to the AlCl3 unit via its oxygen atom; consequently, a lengthening of the CO bond is observed. The (CH3)2N units are less twisted relative to the OCN2 plane than in the free ligand. Solutions of AlCl3·OC(NMe2)2 in diethylether contain both the initial molecular adduct 1 and the ether adduct AlCl3·OEt2. In tetramethyl urea, compound 1 dissociates predominantly into the ions AlCl4- and {Cl2Al[OC(NMe2)2]2}+ . These solutions have been studied by 27Al NMR spectroscopy.

scholarly journals The magnetic and optical properties of the benzene ring in aromatic compounds

1929 ◽  
Vol 126 (800) ◽  
pp. 143-154 ◽  
Keyword(s):  
Crystal Lattice ◽  
Benzene Ring ◽  
Unit Cell ◽  
Organic Crystals ◽  
Parallel Plates ◽  
X Ray ◽  
Suitable Material ◽  
Starting Point ◽  
Sufficient Precision ◽  
Complete Interpretation

The present paper describes the third of a series of investigations undertaken at the suggestion of Sir C. V. Raman of the remarkable magnetic and optical characters exhibited by organic crystals of the aromatic class. In the earlier papers the author had described the optical and the magnetic characters of naphthalene crystals and also of anthracene and other organic compounds and discussed the significance of the results. In all these cases, however, the fact that there were two or more molecules per unit cell in the crystal lattice, and that the X-ray results available did not fix with sufficient precision either the form of the molecules or their orientation relatively to each other and to the crystal lattice prevented a complete interpretation of the results. Mrs. Lonsdale’s recent admirable investigation of the structure of hexamethylbenzene has made further and very significant progress possible. She has shown that this substance crystallises in the triclinic system with one molecule per unit cell and that the carbon atoms in the molecule form flat hexagonal rings parallel to a cleavage plane. Hence this substance forms a very suitable material for the experimental study of the magnetic and optical characters of the benzene ring in its substitution products. It has accordingly been used as the starting point in the present investigation. For convenience of reference Mrs. Lonsdale's results will be briefly recalled here. The nomenclature adopted is the same as hers. The substance crystallises out of benzene mostly in parallel plates with the be plane prominently developed. Often there are two other pairs of faces, fairly well developed, which were chosen by her as the ab and ac planes. The unit cell thus defined is a triclinic cell which was found to have the following axes and axial angles:— A. U. ° ˊ 9.010 . . . . . . . . . . . . . . . . . 44 27 8.926 . . . . . . . . . . . . . . . . . 116 43 5.344 . . . . . . . . . . . . . . . . . 119 34 The crystal is centrosymmentrical with one molecule per cell.

scholarly journals The nature and properties of aluminosilicate framework structures

1934 ◽  
Vol 145 (854) ◽  
pp. 80-103 ◽  
Keyword(s):  
Water Molecules ◽  
Chemical Formula ◽  
Framework Structure ◽  
Experimental Proof ◽  
X Ray ◽  
Structure Determinations ◽  
The Individual ◽  
Related Compounds ◽  
Ray Methods ◽  
Oxygen Atoms

In recent years it has been shown by X-ray methods that the structures of a large number of crystals are based on frameworks of linked tetrahedral groups of oxygen atoms. The individual tetrahedra contain silicon or aluminium atoms, and other atoms (such as sodium or potassium) and water molecules or molecular groups (such as CO 3 and SO 4 ) are located in the interstices of the oxygen atom arrangement. Some of the structure determinations are incomplete and lack direct experimental proof, but in others it has been possible to discover the details of the atomic arrangement. The present writer has been associated with several of these detailed investigations, and in this paper presents some general conclusions which may be drawn from an examination of the available data. Experimental details and evidence for the correctness of individual structures have been published elsewhere. For the purpose of the present paper a framework structure is defined as one in which every tetrahedron SiO 4 or AlO 4 shares all its corners with other tetrahedra, thus accounting for all the silicon aluminium and oxygen atoms in the structure; such a crystal has a chemical formula in which the ratio (Si + Al) to O is 1 to 2. Framework structures include the forms of silica, the felspars, the zeolites, the ultramarines, nepheline and kaliophilite, and related compounds which will be mentioned later; also danburite if boron may be supposed to take the place of aluminium in our definition, and probably leucite.

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