Josef Hahn

Beiträge zur Chemie des Phosphors, 116 Kernresonanzspektren und Kristallstruktur von Tri-tert-butylcyclotriphosphan / Contributions to the Chemistry of Phosphorus, 116 NMR Spectra and Crystal Structure of Tri-tert-butylcyclotriphosphane

A complete analysis of the 31P, 13C and 1H NMR spectra of tri-tert-butyl-cyclotriphosphane (1) was carried out and the resulting NMR parameters were correlated with the X-ray data of the molecule. It was found, that increasing P-P-C-bond angles correspond to a downfield shift and an increase of the absolute values of the negative 1J(PP) and 1J(PC) coupling constants. Generally, the chemical shifts of cyclotriphosphanes as well as of larger cyclic phosphanes depend on the endo- and exocyclic bond angles, the dihedral angle between the electron lone pairs of adjacent P-atoms, and the β-effect. On the basis of the X-ray and chemical shift data of 1, the bond angles of other cyclotriphosphanes can be deduced from their δ(31P) values. 1 crystallizes triclinically in the space group P1̄ with Z = 4 formula units. The X-ray analysis confirms the NMR-spectroscopically determined three-membered ring structure with the tert-butyl substituents on either side of the ring plane. Due to steric hindrance between the two tert-butyl groups in cis position, the corresponding P-P-C-bond angles show the largest values so far observed for organylcyclophosphanes.

Zusammensetzung von Rohsulfan, Nachweis der Sulfane H2S9 bis H2S35 Composition of Crude Sulfane Oil, Identification of the Sulfanes H2S9 to H2S35

In benzene solution the position of the 1H NMR signals of sulfanes, H2Sn, strongly depends on the sulfur chain length and on the sulfane concentration. Under proper conditions all sulfanes in a mixture are characterized by well-resolved NMR signals showing a downfield shift with increasing length of the sulfur chain. The shift differences between the higher homologues ( n > 8 ) remain nearly constant, thus allowing the assignment of the signals up to H2S35 and the determination of the complete sulfane distribution in crude oils. In sulfane mixtures without solvent as well as in CS2 and CCl4 solutions, however, H2S8 shows the largest downfield shift. The signals of the higher sulfanes overlap in a narrow range at slightly higher field and cannot be characterized except for the CCl4 solution where an assignment up to H2S11 is possible. The chemical shifts are interpreted in terms of inter- and intramolecular hydrogen bondings. The upfield shift caused by benzene is attributed to the formation of H2Sn · benzene complexes.

Beiträge zur Chemie des Silieiums und Germaniums, XXIX [1] 29Si-NMR-spektroskopische Untersuchungen von geradkettigen und verzweigten Silanen / Contributions to the Chemistry of Silicon and Germanium, XXIX [1] 29Si NMR Spectroscopic Investigations on Straight and Branched Silanes

, The structure of the straight silanes SinH2n+2 (1 ≤ n ≤ 7) and of the branched isomers isotetrasilane, iso- and neopentasilane, 2-silyl- and 3-silylpentasilane, 2,3-disilyltetrasilane as well as 2-silyl- and 3-silylhexasilane could be unambiguously elucidated by 29Si NMR spectroscopy. Systematic trends in the chemical shift and coupling parameters were observed and an empirical relationship between δ(29Si) of a 29Si nucleus and the number of the neighbouring silicon atoms in αβor γposition is given. In 1H decoupled spectra the nuclear Overhauser effect on the 29Si resonance was found to increase with increasing distance of the 29Si nucleus from the end of the chain. A complete analysis of the multi spin systems of disilane, trisilane and isotetrasilane was performed and the signs of the 29Si,H- and H,H-long range coupling constants were determined with regard to the negative sign of 1J(29SiH).

Beiträge zur Chemie des Phosphors, 96 [1] Darstellung und 31P-Kernresonanzspektrum von isotopen-substituiertem Trilithium-heptaphosphid, 6Li3P7 / Contributions to the Chemistry of Phosphorus, 96 [1] Preparation and 31P NMR Spectrum of Isotopicly Substituted Trilithiumheptaphosphide, 6Li3P7

Abstract The P7-skeleton of trilithiumheptaphosphide, Li3P7 (1), was proved to possess the earlier reported tricyclic structure [2] by complete analysis of the 31P NMR spectrum of 6Li3P7 observed at - 60 °C. The 6Li isotopic substitution was carried out to avoid the line broadening caused by the large quadrupole moment of the 7Li isotope. The unambiguous elucidation of the Li3P7 structure confirmed that the exchange process which causes all P atoms to become equivalent above room temperature is analogous to that in bullvalene. A comparison of the chemical shifts with those of (Me3Si)3P7 leads to the result that the P7-skeleton in Li3P7 is noticeably compressed along its threefold axis, thus indicating a predominant ionic character.

Bis(methvldiphenvlsilvl)-sulfane: Ausgangsverbindungen zur Darstellung von Sulfanen H2Sn und D2Sn mit definierter Kettenlänge / Bis(methyldiphenylsilyl)-sulfanes: Starting Compounds for the Preparation of Sulfanes H2Sn and D2Sn of Definite Chain Length

The silylsulfanes (MePh2Si)2Sn, n = 2-5 (1a-d). have been prepared by reacting MePh2SiSNa (2) with iodine or chlorosulfanes SmCl2, m = 1−3. in toluene solution. Compounds 1a-d, which can unambiguously be characterized by their 1H and 29Si chemical shifts, are obtained pure when crystallized from solutions in pentane or pentane/CS2. They proved a convenient source for the generation of sulfanes H2Sn and deuterosulfanes D2Sn of definite chain length n = 2-5. Mixtures of the silylated sulfanes (MePh2Si)2Sn, n = 1−10. are formed on heating 2 with an excess of cyclooctasulfur.

Beiträge zur Chemie des Phosphors, 139 [1] Triethyl-cyclotriphosphan, Trimethyl-cyclotriphosphan; Gleichgewichte zwischen Cyclophosphanen (PR)n bei erhöhten Temperaturen/Contributions to the Chemistry of Phosphorus, 139 [1] Triethylcyclotriphosphane, Trimethylcyclotriphosphane; Equilibria between Cyclophosphanes (PR)n at Elevated Temperatures

Triethylcyclotriphosphane, (PEt)3 (1), has been generated by thermolysis of tetraethylcyclotetraphosphane, (PEt)4. 1 can be obtained as a 43% solution in 1,2,3-triethyl-1,2,3-triphosphole, (PEt)3C2H2 (3), by fractional distillation of the product mixture formed in the reaction of K2(PEt)4 with ClHC=CHCl. 3 has been isolated and fully characterized. Furthermore 1 as well as (PMe)3 (2) and (PPh)3 exist besides (PR)4 (R = Et, Me, Ph) in thermodynamic equilibrium with (PR)5 at elevated temperatures; for R = Ph(PPh)6 is also formed. The thermodynamic data of the reactions 3/5 (PMe)5 ⇌ (PMe)3 and 4/5 (PMe)5 ⇌ (PMe)4 have been calculated from the equilibrium constants between 60 and 160 °C. The ring strain of 2 is much smaller than that of cyclopropane but increases with increasing size and bulk of the substituents R at the phosphorus threemembered ring.

Beiträge zur Chemie des Phosphors, 125/Synthese und Struktur der Triorganyl-nonaphosphane(3) P9(i-Pr)3 und P9 (t-Bu)3

Abstract The triorganyl-nonaphosphanes(3) P9(i-Pr)3 (1) and P9(t-Bu)3 (2) have been obtained by reacting (i-PrP)4 with PCl3 and by dehalogenating a mixture of t-BuPCl2 and PCl3 with magnesium, respectively. In the case of P9Et3 (3) and P9Me3 (4) the latter reaction may be modified by using the organyl-cyclophosphanes (PR)n instead of RPCl2. P7R3 as well as other polycyclic organylphosphanes are formed as by-products. 1 could be isolated in pure form and 2 has been concentrated in the product mixture. According to their 31P{1H}-NMR spectra 1-4 possess a P9 skeleton analogous to that of the hydrocarbon deltacyclane. 1 and 2 are formed as mixtures of two configurational isomers, which differ in the spatial arrangements of the substituent on P5. The results clearly indicate, that the corresponding phosphorus hydride P9H3 has the same structure and is a tetracyclo[4.3.0.02,4.03,7]nonaphosphane.

Beiträge zur Chemie des Phosphors, 208 [1] / Contributions to the Chemistry of Phosphorus, 208 [1]

The valence tautomerism of the heptaphosphanortricyclene anion P73- has been studied by means of a two-dimensional 31P NMR exchange spectrum. The rearrangement process of the P atoms postulated earlier [2] has been confirmed in all details.

Beiträge zur Chemie des Phosphors, 204. Zur Existenz eines Triphosphacyclobutenid-Ions P3CH2Ɵ / Contributions to the Chemistry of Phosphorus, 204. On the Existence of a Triphosphacyclobutenide Ion P3CH2e

The structure of the reaction product of white phosphorus and sodium in diglyme which exhibits a low field AB2 system in the 31P{1H} NMR spectrum [4] has been reexamined. According to the results of a complete analysis of its proton coupled 31P NMR spectrum (ABB′XX′ system), the compound is the hitherto unknown 1,2,3-triphosphacyclopentadienide ion P3(CH)2⊖ (4), and not the triphosphacyclobutenide ion P3CH2⊖(3) previously assumed [4]. The parameters of the Ρ,Η-coupled 31P NMR spectrum of the tetraphosphacyclopentadienide ion P4CH⊖ (2) have also been calculated.

δ Beiträge zur Chemie des Phosphors, 120 [1] Carbonyl-Triorganylcyclotriphosphan-Komplexe von Chrom und Wolfram / Contributions to the Chemistry of Phosphorus, 120 [1] Carbonyl-Triorganylcyclotriphosphane Complexes of Chromium and Tungsten

The reaction of triorganylcyclotriphosphanes, (RP)3 (R = i-Pr, t-Bu), with metal carbonyl-tetrahydrofuran complexes, M(CO)5THF (M = Cr, W), yields the novel mononuclear and binuclear cyclotriphosphane-carbonylmetal complexes (RP)3M(CO)5 (R = i-Pr, t-Bu; M = Cr, W) 1-4 and (RP)3[M(CO)5]2 (R = t-Pr, M = Cr) 5, respectively. They are remarkably stable both thermally and to oxidation. Their structures have been elucidated by 31P NMR spectroscopic investigations. The cyclotriphosphane functions as a 2- or a 4-electron donor, respectively, and behaves as a Ti-acceptor comparable to Ph3P