bluuebunny/crossref_metadata_2025_split huggingface dataset:
Darstellung und Kristallstruktur des Niob-(triphenylphosphinimino)tetrachlorids, Nb [NP (C6 H5 )3] Cl4, einer Verbindung mit einer Niob-Stickstoff-Mehrfachbindung /Preparation and Crystal Structure of Niobium(triphenyl-phosphineimino)tetrachloride, Nb[NP(C6H5)3]Cl4, a Compound with a Niobium Nitrogen Multiple Bond
Authors: Bezier Hans , Strahle Joachim 
Published: February 2015

Abstract
Nb[NPPh3]Cl4 can be prepared by reacting NbCl4N3 with PPh3 in 1,2 dichloro ethane. The crystalline, yellow compound crystallizes in the monoclinic space group C2/c. The crystal structure consists of eight molecules, which are linked together via bridging chlorine atoms to centrosymmetric dimers. Thereby the niobium atoms obtain a sixfold coordination by one N and five Cl atoms. The triphenyl phosphine imine ligand is bound to niobium by its N atom. The approximate linearity of the resulting Nb-N-P group (angle Nb-N-P = 171°) and the distances Nb-N - 178 pm and N-P =164 pm can be interpreted by an sp hybridized N atom and double bonds to both the Nb and P atom.
The Crystal Structure of Eu11Sb10
Authors: Schmelczer R. , Schwarzenbach D. , Hulliger F. 
Published: February 2015

Abstract
Eu11Sb10 crystallizes in the tetragonal Ho11Ge10 structure type, space group I4/mmm, with a = 12.325(2), c = 18.024(4) Å; Z = 4. Large thermal parameters of certain atoms and unusual interatomic distances might suggest that the true structure is slightly distorted, but attempts to desymmetrize the structure were unsuccessful. Analogous anomalies occur in most of the other representatives of the Ho11Ge10 type. Eu11Sb10 appears to be metallic. It contains divalent Eu and is antiferromagnetic below TN ≈ 5 K. Other new representatives of the Ho11Ge10 structure type are Sr11Sb10, Sr11Bi10 and Ba11Sb10.
Ternäre Silicide des Lithiums mit Yttrium oder Neodym mit modifizierter U3Si2-Struktur /Ternary Silieides of Lithium with Yttrium or Neodymium in a Modified U3Si2-Type Structure
Authors: Steinberg Gunter , Schuster Hans-Uwe 
Published: February 2015

The two isotypic compounds LiY2Si2 and LiNd2Si2 were prepared and chemically characterized. The crystal structure determination of LiY2Si2 by means of X-ray methods revealed a modified U3Si2-structure. The lattice constants of the tetragonal cells are:
LiY2Si2: a = 710.5 pm, c = 414.4 pm.
LiNd2Si2 : a = 737.0 pm, c = 424.2 pm.
Reaktionen polyhalogenierter Cyclobutane mit Trimethylphosphit /Reactions of Polyhalogenated Cyclobutenes with Trimethylphosphite
Authors: Bauer Gert , Hagele Gerhard , Sartori Peter 
Published: February 2015

Abstract
Polyhalogenated cyclobutanes are synthesized and dehalogenated to cyclobutenes by means of trimethylphosphite.
13C-NMR-Untersuchiingen an einigen Organosilanen /13 C NMR Studies on Some Organosilanes
Authors: Wrackmeyer Bernd , Biffar Werner 
Published: February 2015

Abstract

13C-NMR data (δ13C, J(13C1H), J(13C13C), J(29Si13C)) of noncyclic organosilanes CH4-n[Si(CH3)3]n (n = 1-4), (CH3)4-nC[Si(CH3)3]n (n = 1, 3, 4) and cyclic organosilanes [(CH3)2SiCH2]n (n = 2, 3), (CH3)2Si(CH2)3 are reported. Comparison of reduced coupling constants 1K proves the Fermi-contact-term to be the dominant coupling mechanism. Structural features of the four-membered heterocycles become apparent by comparison of their 13C NMR parameters with those of corresponding cycloalkanes, noncyclic organo­silanes and the 1,3,5-trisilacyclohexane derivative.
Sila-Pharmaka, 14. Mitt. Darstellung und Eigenschaften sowie Kristall-und Molekülstruktur von Sila-Difenidol /Sila-Drugs, 14th Communication Preparation and Properties as well as Crystal and Molecular Structure of Sila-Difenidol
Authors: Tacke R. , Strecker M. , Sheldrick W. S. , Heeg E. , Berndt B. , Knapstein K. M. 
Published: February 2015

Abstract
Sila-difenidol (6b), a sila-analogue of the drug difenidol (6a), was synthesized according to Scheme 1. 6b and its new precursors 3 and 5 were characterized by their physical and chemical properties, and their structures confirmed by elementary analyses, 1H NMR and mass spectroscopy. 6 b crystallizes orthorhombic P212121 with a = 11.523(1), b = 14.366(4), c = 11.450(1) Å, Z = 4, Dber = 1.14 gcm-3. The structure was refined to R = 0.050 for 1897 reflexions. A strong nearly linear intramolecular O-H···N hydrogen bond of 2.685 Å is observed. The anticholinergic, histaminolytic and musculotropic spasmolytic activities of 6 a and 6 b are reported.
Structure of the 1-Ethyl-3-methyl-1-alumina-indane Dimer, [C2H5(O-C6H4CH(CH3)CH2)Al]2
Authors: Brauer David J. , Krüger Carl 
Published: February 2015

Abstract
The molecular structure of the 1-ethyl-3-methyl-1-alumina-indane dimer has been determined from single crystal X-ray data collected by counter methods. The compound crystallizes in the monoclinic space group C2h
5-P21/c with a = 14.621(2), b = 8.3967(3), c = 8.7516(5) Å, β = 107.998(4)°, Z = 2 and dc = 1.15 gem-3 . Refinement converged with an R value of 0.037 for the 1836 reflections with I > 3 σ (I). The crystals are composed of discrete dimeric molecules possessing crystallographic 1̄ (Ci) symmetry. Each Al atom bonds to an ethyl C atom, 1.964(2) Å, as well as to alkyl 1.974(2) and aryl 2.168(1) Å C atoms of one monomer and, surprisingly, to the aryl C atom 2.104(1) Å, of the inversion related monomer. The Al-Al′ distance in the dimers is 2.6639(7) Å.
[1.3] -Hydroxylwanderung bei Radikalkationen von Allen-und Acetylenalkoholen/[1,3]-Hydroxyl Migration in Cation Radicals of Allene and Acetylene Alcohols
Authors: Ciommer Bernhard , Schwarz Helmut 
Published: February 2015

Abstract
Contrary to previous conclusions it is shown that the molecular ions of 1, 2, and 3 do not interconvert prior to dissociation. Investigation of labelled compounds establishes a new typ of intramolecular [1,3]-hydroxyl migration to allenic and acetylenic carbons. It is shown that both 1 and 2 undergo irreversible rearrangement to an a,β-unsaturated ketone 4. Methyl loss from the intermediate 4, which accounts for 90% of the total methyl elimination, is preceded by partial hydrogen exchange processes between the three methyl groups of 4. The actual dissociation can be described as an a-cleavage to the carbonyl function. The unusual formation of CH3CO+ " is shown to occur exclusively from 1. However, it is demonstrated that prior to CH3CO+ formation 1 rearranges to m. The mechanistic details of this as well as alternative processes are discussed.
Chemical Constituents of Corchorus capsularis and C.olitorius (Jute Plant), Part IV Isolation of Corosolic Acid, Ursolic Acid and corosin and Correlation of Corosin with Tormentic Acid
Authors: Manzoor-i-Khuda M. , Habermehl Gerhard 
Published: February 2015

Abstract
Three triterpenoids have for the first time been isolated from fresh undried jute root, ursolic acid as its acetate, corosolic acid as its acetate and indicated to be urs-2a,2β-diol-12-en-28-oic-acid and oxo-corosin isolated as its acetate-methyl-ester, C36H54O10, m.p. 160 °C, aD-15° (c 0.435%). The 24-carboxyl in corosin-anhydro-lactone-acetate has been reduced to the methyl group and the resultant lactone on acetylation indicated to be identical with tormentic acid lactone acetate.
Konformation sterisch gehinderter Anilin-Kationradikale und Benzyl-Kationen/On the Conformation of Sterically Hindered Aniline Cation Radicals and Benzyl Cations
Authors: Woynar Helmut , Schäfer Hartmut , Berndt Armin , Thiel Walter , Schweig Armin 
Published: February 2015

Abstract
A series of aniline cation radicals have been generated in a flow apparatus, and their ESR spectra have been recorded and interpreted. The data show that the NR1R2 substituents are less twisted in these systems than the CR1R2 substituents in the isoelectronic but sterically less hindered benzyl radicals, in accordance with MNDO calculations. The conformations of these systems are strongly influenced by electronic π-resonance effects which limit the usefulness of steric models for structural predictions. The results suggest that the CR1R2 substituent in the benzyl cations is less twisted than in the corresponding radicals. An ESR measurement of these radicals should therefore provide an upper limit to the twist angle in the cations, which is difficult to determine otherwise by experiment.
[(C5H5)CO{P(0)(0C2H5)2}3]-: Eine einfache Synthese eines metallorganischen Tripodliganden und seine Reaktivität gegenüber den Kationen der III. Hauptgruppe / [(C5H5)CO{P(0)(0C2H5)2}3]-: A Convenient Synthesis of an Organometallic Tripod Ligand and its Reactivity towards the Main Group III Cations
Authors: Kläui Wolfgang 
Published: February 2015

Abstract
A simple two step synthesis of the salts M[(C5H5)Co{P(0)(OC2H5)2}3], M = Li, Na, K, Ag, NH4, NMe4 is described. The air stable, diamagnetic anion reacts as a tridentate 0,0,0-chelating ligand with all main group III elements. With sodium tetraphenylborate the cage-like cationic complex [(C5H5)Co{[P(0)(OC2H5)2]3BPh}]+ is obtained. With M(III) = Al,Ga, In, Tithe trinuclear sandwich compounds [{(C5H5)Co[P(0)(OC2H5)2]3}2M]+ are formed, which contain MO6 octahedra. With M(III) = TI a coupling constant 6J(T10P0CCH) = 1.0 Hz is observed.
Sila-Pharmaka, 15. Mitt. [1] Synthese und Eigenschaften des Sila-Pridinols / Sila-Drugs, 15th Communication [1] Synthesis and Properties of Sila-Pridinol
Authors: Steiling Lothar , Wannagat Ulrich 
Published: February 2015

Abstract
Synthesis of the silicon analogue VI b of the drug pridinol and of its homologue VI a was achieved via eq. (l-5b) (Scheme 1). The novel compounds IVa-VIb are described in their properties and confirmed in their structures (Tables I-IV). Some preliminary pharma-cological investigations suggest spasmolytical effects of sila-pridinol seeming to be somewhat better than those of pridinol itself.
Darstellung und Eigenschaften von Naphtho[1.2-d] -und Naphtho [2.3-d]-1.3-dioxolen / Preparation and Properties of Naphtho[1,2-d]-and Naphtho[2,3-d]-1,3-dioxoles
Authors: Daliacker Franz , Morcinek Ralf , Rabie Arafat 
Published: February 2015

We describe the preparation of unsubstituted 1 a, of 4-methoxy- (1b), and of 5-methoxynaphtho[1,2-d]-1,3-dioxole (1 c). Treatment of 1 a with bromine leads to 5-bromo-naphtho- [1,2-d]-1,3-dioxole (1d). The carboxylic acid 1f and 5-methyl-thio-naphtho[1,2-d]-1,3- dioxole (lg) are prepared by bromine-lithium-exchange from ld. Formylation yielding 1i and bromination yielding 1h show that 4-methoxy-naphtho[1,2-d]-1,3-dioxole can easily undergo electrophilic substitution.
Because of less Ss-reactivity of 1c the carboxylic acid 1l and methyl-thio-naphtho[l,2-d]- 1,3-dioxole (In) can only be prepared from the lithium-compound as intermediate. Naphtho[2,3-d]-1,3-dioxole (2a) can easily undergo electrophilic substitution, showed by nitration yielding 2b, acetylation yielding 2c, bromination yielding 2d and 2e. The carboxylic acid 2j, the methyl-derivative 2k, the thionaphthole 2l, and the aldehyde 2m are prepared from the lithium-compound of 2d.
Treating 2e with n-butyl-lithium leads to the dilithium-naphthyl derivative, a suitable starting material to obtain the dimethyl-compound 2n, the dicarboxylic acid 2o, and the dialdehyde 2p. Monomethyl-thio- 2q) and dimethyl-thio-naphtho[2,3-d]-1,3-dioxole (2r) are prepared in the same manner.
Fluorescein-Photosensitized Furan Oxidation in Methanolic and Reversed Micellar Solutions, Part I. Effects of Amines
Authors: Miyoshi Norio , Tomita Giiti 
Published: February 2015

Abstract
The 1,3-diphenylisobenzofuran oxidation reaction was investigated in methanolic and dodecylammonium propionate reversed micellar solutions using fluorescein sodium as photosensitizer. It was found that aniline remarkably enhanced the furan oxidation in methanolic solutions but inhibited it in reversed micellar solutions. This enhancement effect occurred more effectively at lower oxygen concentrations. It was proposed that, in the former solutions, the radical mechanism (Type I) might be involved in the furan oxidation in the presence of aniline besides singiet oxygen mechanism (Type II). The reversed micelle seems to inhibit the Type I reaction, resulting in no enhancement of the furan oxidation by aniline.
Darstellung, Struktur und Eigenschaften einer neuen Modifikation von NbI5 / Preparation, Structure and Properties of a New Modification of NbI5
Authors: Krebs Bernt , Sinram Diethard 
Published: February 2015

Abstract
Triclinic niobium(V) iodide was prepared from the elements at an iodine pressure of 3-4 bar in a temperature gradient from 400 to 230 °C. It crystallizes in the space group P1̄ with a = 7.591(3), b = 10,322(3), c = 6.977(3) Å, α = 90.93(3), β = 116.17(3), γ = 109.07(3)°, Z = 2 Nbls. The single-crystal X-ray structure analysis shows the compound to contain dimeric Nb2I10 molecules with Nb-I bond lengths of 2.933 and 2.939(1) A for the bridge bonds and of 2.639···2.720(1) Å for the terminal bonds. The structure is isotypic with triclinic β-UCl5. The infrared spectrum indicates stretching vibrations at 148, 202, 214 and 242 cm-1 .
29Si-Kernresonanzuntersuchiingeii an Polysilanen 1. Perchlorpolysilane / 29Si NMR Investigations on Polysilanes 1. Perchloropolysilanes
Authors: Marsmann H. C. , Raml W. , Hengge E. 
Published: February 2015

Abstract
Several oligomeric perchloro silanes of the type Cl2n+2Sin (n= 1 to 6) were studied by 29Si NMR. n-Cl12Si5 was synthesized for the first time. Structures of isomeric silanes could be determined by substituent effects.
Reaktionen koordinierter Liganden, VI [1] Substituenteneinflüsse bei der Bildung von Tri- und Tetraphosphinen in der Koordinationssphäre von Übergangsmetallen / Reactions of Coordinated Ligands, VI [1]. Influence of Substituents on the Formation of Tri- and Tetraphosphines in the Coordination Sphere of Transition Metals
Authors: Stelzer Othmar , Weferling Norbert 
Published: February 2015

Abstract
The lithiumphosphido complex cis-Mo(CO)4(Me2PLi)2 reacts with dichlorophosphines RPCl2(R = Ph, But) to give coordination compounds of tetraphosphines Me2P-PR-PR-PMe2, whereas the complex of the triphosphine cis-Mo(CO)4 (Ph2P-PMe-PPh2) is obtained starting with the lithiumphosphido complex cis-Mo(CO)4(Ph2PLi)2. Phenyldilithiumphosphine and the chlorophosphine complexes cis-Mo(CO)4(R2PCl)2 (R = Me, Ph) give in low yield cis-Mo(CO)4(R2P-PPh-PPh-PR2) and cis-Mo(CO)4(R2P-PPh-PR2). The mechanisms of these reactions are discussed. The {31P}1H- and {1H}31P-NMR spectra are analysed and correlated with the structures of these complexes.
Übergangsmetall-Carbin-Komplexe, LVI [1]. Umsetzung eines kationischen Carbin-Komplexes mit einem Carbonylmetallat. Der Phenylketenyl-Rest als Briickenhgand / Transition Metal Carbyne Complexes, LVI [1]. Reaction of a Cationic Carbyne Complex with a Carbonylmetalate. The Phenylketenyl Group as a Bridging Ligand
Authors: Orama Olli , Schubert Ulrich , Kreißl Fritz Roland , Fischer Ernst Otto 
Published: February 2015

Abstract
By reaction of [(π-H5H5)(CO)2Mn≡C-C6H5]BCl4 with NaRe(CO)5 a new type of complex is obtained. It crystallizes in the monoclinic space group P21/c, Z = 4, a - 1115(1), b= 1464(1), c= 1657(2) pm, β= 136.79(8)°. Structure determination reveals a binuclear complex, the Mn-Re bond (281.7(3) pm) of which is bridged by the a-carbon atom of a phenylketenyl group (Mn-C 221(3), Re-C 224(3) pm) and semi-bridged by a CO group (Mn-C 187(4), Re-C 254(4), Mn-C-0 160(3)°).
Studies on Betaine Decomposition of Arsonium Ylides
Authors: Tewari R. S. , Suri S. K. , Gupta K. C. 
Published: February 2015

Abstract
Betaine, Arsonium Ylides A systematic study on the nature of decomposition of betaine formed by nucleophilic attack of semistabilized arsonium ylides on thiocarbonyl substrates has been carried out. A series of substituted benzylidenetriphenylarsenanes have been generated from their corresponding salts and condensed with few cyclic thioketones to yield exocyclic olefins as exclusive products. The non-availability of thioepoxides indicates that the mode of decomposition of such type of betaines is quite analogous to the betaine formed by phosphonium ylides. The structure of the products have been assigned by IR and NMR spectral studies.
Transylidation Reactions in Arsonium Ylides
Authors: Tewari Ram S. , Nagpal Dinesh K. 
Published: February 2015

Abstract
Some substituted benzylidenetriphenylarsenanes have been generated from their precursors and treated with acid chlorides or acid anhydrides to afford intermediate arsonium salts which in the presence of starting ylides undergo transylidation to give carbonyl stabilized arsonium ylides in fair to good yields. The structures of these stabilized ylides were confirmed on the basis of their spectral data.
Hydroxylation of ⊿5-Steroids with N-Bromosuccinimide to 5α,6β-Diols
Authors: Dawidar A. M. , Saleh A. A. , Abdel-Malek M. M. 
Published: February 2015

Abstract
The reaction of N-bromosuccinimide with ⊿5 -steroids such as, diosgenin, cholesterol, stigmasterol and dehydroisoandrosterone were studied. It was found that NBS in a solvent mixture of acetone, water and acetic acid (8:1:0.1) oxidises the olefinic bond of all the previous steroidal compounds to the corresponding transglycollic, 5α,6β-di-hydroxylic products in about 60% yield at room temperature.
X-ray Structural Study of 5-Phenyl-10,11-dihydrodibenzo[b,f]phosphepin-5-oxide
Authors: Allen David W. , Nowell Ian W. , Walker Philip E. 
Published: February 2015

Abstract
Crystals of the title compound are triclinic, a = 8.533(5), b = 11.106(6), c = 8.815(5) Å, a = 107.83(6), β = 104.99(6), γ = 81.30(5)°, Z = 2, space group P1̄. The structure was determined by multisolution direct methods and electron density methods. Refinement by least-squares techniques gave a final R = 0.081 for the 1753 independent reflections. The molecule adopts a butterfly-type conformation such that the fused phenyl rings are inclined to each other at an angle of 56.8°. The P-0 bond distance is 1.506(4) Å; the endocyclic angle at phosphorus is 107.2(3)° and the exocyclic angles vary from 106.5 to 111.9(3)°.
Umsetzungen von Metall- und Metalloidverbindungen mit mehrfunktionellen Molekülen, XXV [1]. Thioureidoborane und Isothioureidoborane / Reactions of Metal and Metalloid Compounds with Polyfunctional Molecules, XXV [1]. Thioureidoboranes and Isothioureidoboranes
Authors: Maringgele Walter 
Published: February 2015

Abstract
N,N',N'-Triorganyl-N-trimethylsilylthioureas react with halogeno diorganyl boranes to yield the N,N',N'-organyl-thioureidoboranes 1-7 and isothioureidoboranes 8-15. 10-15 are intramolecularly associated. The compounds are characterized analytically and spectroscopically (NMR: 1H, 13C, HB; MS; IR).
Methyl-Eliminierung aus dem metastabilen Homoadamantan-Radikalkation / Methyl Loss from Metastable Homoadamantane Cation Radical
Authors: Schwarz Helmut , Wesdemiotis Chrysostomos , Weiske Thomas , Schwarz Helmut , Wesdemiotis Chrysostomos , Weiske Thomas 
Published: February 2015

Abstract
It is demonstrated that methyl loss from ionized homoadamantane (1) yields exclusively the 1-adamantyl cation (4); there is no experimental evidence for the formation of the secondary adamantyl cation (5). From both model calculations and the investigation of [4-13C]-homoadamantane (1a) and 1(13C-methyl)adamantane (2a) it is concluded, that 24% of the metastable homoadamantane cation radicals dissociate after one isomerization (1→2); the remaining 76% are able to undergo at least a second (degenerate) isomerization cycle (2→1→2) prior to methyl loss. 78% of metastable 1-methyl-adamantane cation radical, obtained upon direct ionization of the corresponding neutral hydrocarbon, dissociate directly, whereas the loss of methyl from the remaining 22% is preceded by an isomerization 2 →1 →2.
Pyrolysis Mass Spectrometry of Protected Phosphotriester Oligodeoxyribonucleotides
Authors: Ulrich J. , Bobenrieth M. J. , Derbyshire R. , Finas F. , Guy A. , Odin F. , Polverelli M. , Téoule R. 
Published: February 2015

Abstract
Pyrolysis mass spectrometry is shown to be a useful tool in the analysis of the protected intermediate deoxy oligonucleotides synthesized by the phosphotriester approach. Characteristic ions of the protected nucleic acid bases and terminal substituents appear in the mass fragmentation pattern which allows a rapid control of the attachment of the polynucleotide block in the chemical synthesis.
Alkaloide in Tabernaemontana-Arten, XI [1]. Untersuchung der Alkaloide von Tabernaemontana quadrangularis — (20R)-20-Hydroxyibogamin, ein neues Alkaloid aus T. quadrangularis / Alkaloids in Tabernaemontana Species, XI [1]. Investigation of the Alkaloids from Tabernaemontana quadrangularis — (20R)-20-Hydroxyibogamine, a New Alkaloid from T. quadrangularis
Authors: Achenbach Hans , Raffelsberger Bernd 
Published: February 2015

Abstract
From the methanolic extract from the roots of T. quadrangularis we isolated 14 alkaloids (1-14) and deduced their structures. All the alkaloids are of the ibogamine-type or im-mediately related to it; (20R)-20-hydroxyibogamine (5) was found for the first time as a natural product.
Die Kristallstruktur des Tl10Hg3Cl16 / The Crystal Structure of Tl10Hg3Cl16
Authors: Brodersen Klaus , Jensen Klaus-Peter , Thiele Gerhard 
Published: February 2015

Abstract
The structure of Tl10Hg3Cl16 (tetragonal; space group I4/m; a - 849,0(2) pm, c = 2372,9(6) pm) was determined by X-ray structure analysis. This compound consists of HgCl4 tetrahedra and linear Cl-Hg-Cl units, which are completed by four additional chlorides to distorted (2 + 4) HgCl6 octahedra. A close relationship to the Tl4HgX6 structure (X = Br, I) is discussed.
1.3-Silylgruppenwanderung im Si2NSiN-Gerüst - Synthese und Molekülstruktur von 1.3-Diaza-2.4-disilacyclobutanen / 1,3-Migration of Silylgroups in the Si2NSiN-System - Synthesis and Molecular Structure of 1,3-Diaza-2,4-disilacyclobutanes
Authors: Clegg William , Klingebiel Uwe , Krampe Cornelia , Sheldrick George M. 
Published: February 2015

Abstract
N-Organylamino-N′,N′-bis(trimethyl)amino-fluoroorganylsilanes react with butyl-lithium to give the corresponding lithium salts. Further reaction of these lithium salts with fluorosilanes leads to the formation of the expected substituted compounds. Diaza-disilacyclobutanes are formed by thermal LiF elimination in THF. The simultaneous 1,3-migration of a trimethylsilyl group from one nitrogen atom to another is demonstrated by the crystal structure determination of the products of two such reactions, with different substituent groups.
Borchelate und Bormetallchelate, VI [1] Zur Bildung von Borchelaten aromatischer Azoverbindungen / Boron Chelates and Boron Metal Chelates, VI [1]The Formation of Boron Chelates of Aromatic Azo Compounds
Authors: Hohaus Eberhard , Wessendorf Klaus 
Published: February 2015

Bidentate chelate reagents incorporating a suitable group (e.g. OH, NH2) in ortho position to the azo-group react with diphenylboronic acid anhydride or boron trihalides (BF3, BCl3) resulting in the BR2-six membered ring-chelates of types 1 and 2.
The products of the reaction of tridentate chelate reagents with phenylboronic acid or boron trifluoride at elevated temperature are BR-chelates with two six membered rings (types 3 and 4).
The conditions of the formation of the bicyclic chelates 5 and 6 depend on the position of the substituents of the chelate reagents.
The incorporation of only one BR2 group is possible if the order of the substituents in 2,2′-dihydroxyazobenzenes is not symmetrical (chelates of the type 7).
Structural isomers of boron chelates of the types 5, 6 or 7 with Nα/Nβ isomerism have not yet been observed. The identification of the structures of the above-mentioned complexes was achieved by means of 1H, 11B and 19F NMR and IR spectroscopy. For mass spectrometric analysis see ref. [2].