Gisbert Großmann

Diselenadiphosphetandiselenide und Triselenadiphospholandiselenide - Synthese und Charakterisierung mittels31P- und77Se-Festkörper-NMRSpektroskopie

1,3-Diselena-2,4-diphosphetan-2,4-diselenide, (RPSe2)2, mit R = Me, Et, t-Bu, Ph, 4-Me2NC6H4, 4-MeOC6H4 wurden nach verschiedenen Methoden hergestellt. Von den unloslichen Verbindungen wurden 31P- und 77Se-CP-MAS-Seitenbandspektren aufgenommen. Auf diese Weise konnte die Reinheit kontrolliert und an Hand der isotropen und anisotropen Werte der chemischen Verschiebungen sowie der Kopplungskonstanten 1JP–Se die Struktur der untersuchten Verbindungen bewiesen werden. Auserdem wurden zwei unter ahnlichen Synthesebedingungen entstehende 1,2,4-Triselena-3,5-diphospholan-3,5-diselenide, (RPSe2)2Se (R = Me, Et), untersucht, von denen die Struktur sowohl aus den 77Se-Satelliten der 31P-Losungsspektren als auch aus Festkorperspektren abgeleitet wurde. Am Beispiel von (t-BuPSe2)2 wurden die experimentell aus den Seitenbandspektren ermittelten Hauptachsenwerte der Phosphor- und Selen-Abschirmtensoren mit den aus IGLOBerechnungen (HF und SOS-DFPT) erhaltenen Werten verglichen und die aus den Berechnungen ermittelten Hauptachsenlagen diskutiert. Diselenadiphosphetane Diselenides and Triselenadiphospholane Diselenides – Synthesis and Characterization by 31P and 77Se Solid-State NMR Spectroscopy 1,3-Diselena-2,4-diphosphetane-2,4-diselenides (RPSe2)2 with R = Me, Et, t-Bu, Ph, 4-Me2NC6H4, 4-MeOC6H4 have been synthesized by different methods. The insoluble compounds were investigated by 31P and 77Se solid-state NMR and the purity of the compounds has been checked by their CP MAS sideband NMR spectra. The structure of the investigated compounds has been confirmed by the isotropic and anisotropic values of the chemical shifts and the 1JP–Se coupling constants. In addition, two new 1,2,4-triselena-3,5-diphospholane-3,5-diselenides, (RPSe2)2Se (R = Me, Et), formed under similar synthesis conditions, were investigated. Their structure was derived from the 77Se satellites of 31P solution spectra and from solid-state spectra. For (t-BuPSe2)2 the experimentally obtained principal values of phosphorus and selenium shielding tensors are compared with values from IGLO calculations (HF und SOS DFPT). The calculated orientations of the principal axes are discussed.

Nuclear magnetic shielding in molecules. The application of GIAO's in LCAO-Xα-calculations

A nonempirical method for the calculation of nuclear magnetic shielding based on the four current density functional formalism is presented. Using SCF-LCAO-Xα-calculations with application of GIAOs effective one particle equations are solved. The results for nuclear magnetic shielding in diatomic molecules are of good quality, compared with other theoretical and experimental data.

NMR investigations on diastereomeric mixtures of bis(dialkoxythiophosphoryl) sulfanes and -polysulfanes containing sec. Butoxy groups. Assignment of 31P, 13C and 1H NMR signals in a mixture of seven diastereomers using shift-correlated 2D NMR spectra

Abstract Synthesizing compounds of the structure diastereomeric mixtures were obtained. If possible, the 31P chemical shifts and P[sbnd]P coupling constants of the individual diastereomers were determined from the 31P NMR spectra of these diastereomeric mixtures. In addition, the mixture of the seven diastereomers of bis(di-sec. butoxythiophosphoryl)disulfane was analyzed using shift-correlated 31P[sbnd]31P {1H}, 13C-31P {1H}, 13C-1H {31P} and 1H-1H {31P) 2D NMR spectra. In this way, the 31P, 13C and 1H chemical shifts and the corresponding coupling constants were assigned to the diastereomers. The appearance of regions of similar chemical shift into which the 1H, 13C and 31P signals of identical atoms or atom groups can be classified is characteristic of all the diastereomeric mixtures investigated. These regions can be explained mainly by the symmetry relations of a molecule moiety (sBuO)2P(S)S[sbnd].

SYNTHESIS AND 31P AND 13C NMR STUDIES OF PYROPHOSPHONIC ACIDS

Abstract Pyrophosphonic acids were prepared by partial hydrolysis of phosphonic acid dichlorides and by de-hydration of phosphonic acids, respectively. The pyrophosphonic acids as well as their ammonium salts were characterized by NMR spectroscopy. The geminal coupling constant 2JPOP was obtained from spectral analysis and its sign was determined by spin tickling experiments. Furthermore, semiempirical quantum chemical calculations of 2JPOP were carried out.

Zur Synthese und Struktur von 8-Nitro-imidazo [1,2-a]pyridinen

SummaryThe title compounds were synthesized by reaction of nitroketene aminals with β-chlorovinylcarbonyl compounds. The chloromethylene malononitriles1 react with nitromethylenimidazolin (2 a) and -benzimidazoles2 b to yield the 8-nitro-2,3-dihydroimidazo[1,2-a]pyridines3 and the 4-nitropyrido[1,2-a]-benzimidazoles6, both containing an amino group. Analogously, from the special 3-chloro-2-propeniminium salt7 and2 a the imidazopyridine derivative9 was formed. The 3-aryl-3-chloro-2-propeniminium salts10 were converted into the nitro-dihydroimidazo[1,2-a]pyridines11 and the pyrido[1,2-a]benzimidazole12 containing the aryl group by reaction with2 a and2 b, respectively. The structures were investigated by 2-dimensional1H/13C-NMR-spectroscopy.

Aluminiumphosphate mit nichtzentrosymmetrischen Schicht-und Raumnetzstrukturen aus topologisch verwandten Motiven: 1. KAl2(PO4)2(OH)·4H2O/Aluminum Phosphates with Non-Centrosym metric Layer-and Framework-Structures of Topologically Related Motifs 1. KAl2(PO4)2(OH)·4H2O

Abstract KAl2(PO4)2(OH)·4H2O could be obtained by the reaction of gibbsite with a potassium-phosphate solution of pH = 5.5 at 333 K. A single crystal X-ray structure analysis showed that KAl2(PO4)2(OH)·4H2O is isotypic with the mineral minyulite. Crystal data: orthorhombic space group Pba2, a = 934.7(1), b = 982, 1 (1), c = 551,0(1) pm, Z = 2. It possesses dimeric units of Al-octahedra which are bridged by an OH-and two bidentate phosphate groups. The dimers are linked by phosphate to plane polar layers. Cavities in the layers are occupied by K ions. One corner of each phosphate tetrahedron is not connected to Al but accepts four hydrogen bonds from water molecules bound to Al of the adjacent layer. A powder neutron scattering experiment with KAl2(PO4)2(OD)·4D2O showed that four D atoms and P coordinate the hydrogen bond accepting O in KAl2(PO4)2(OD)·4D2O like a square pyramid. Analogous dimeric building units are found in the Al phosphate minerals minyulite and morinite; similar dimers of Fe octahedra occur in the mineral copiapite, a number of Fe containing enzymes and numerous synthetic iron complexes. High-resolution 31P solid-state NMR spectra show only one isotropic line at δiso = -9.6 ppm and confirm the presence of one symmetry independent phosphorus site in the unit cell. In the 1H-MAS-NMR spectra the water molecules and the bridging OH groups show signals at 5.4 and 1.4 ppm, respectively

Aluminiumphosphate mit nichtzentrosymmetrischen Schicht- und Raumnetzstrukturen aus topologisch verwandten Motiven: 2. KAl2(PO4)2(OH)·2H2O/Aluminum Phosphates with Non-Centrosymmetric Layer- and Framework-Structures of Topologically Related Motifs: 2. KAl2(PO4)2(OH)·2H2O

Abstract KAl2(PO4)2(OH)·2H2O was obtained by the reaction of gibbsite with a potassium-phosphate solution of pH = 5.5 at 373 K. A single crystal X-ray structure analysis showed that it is an ordered, F-free K-analog of the microporous compound AIPO4-CI2 . Crystal data: orthorhombic space group P212121, a = 920.5(1), b = 970.7(2), c = 982.8(2) pm, Z = 4. The structure consists of dimeric units of AIO6 octahedra and AIO5 trigonal bipyramids, bridged by an OH and two bidentate phosphate groups. The dimers are linked by phosphate to form corrugated layers which are topologically related to the layers in KAl2(PO4)2(OH)·4H2O and minyulite. The layers are connected by Al-O-P and hydrogen bonds to a three dimensional framework structure with K ions in channel-like cavities. A neutron powder scattering experiment with KAl2(PO4)2(OD)·2D2O showed that the bridging OD group and only one D of each water molecule are involved in hydrogen bonding. 31P MAS NMR spectra show two isotropic lines at δiso = -6.9 and -18,7 ppm of the intensity ratio 1:1 and confirm the presence of two crystallographically independent P atoms in the unit cell. In the 1H MAS NMR spectra the water molecules and the bridging OH group show signals at 5.9 and 1.1 ppm, respectively.