W. Hönle

Substituted heptaphosphanortricyclenes: Derivatives and homologues of P7(SiMe3)3

Abstract Homologues and derivatives of P7(SiMe3)3 can be synthesized from Li3P7·3solv or Na3P7, or by cleavage of the PSiMe3 bond with RX. The reaction of Li3P7·3DME with the halogen-containing compounds Ph3SiCl (Ph  C6H5), H3SiI, Me3SnBr (Me  CH3), i-C3H7Br, CpFe(CO)2Br yields P7(SiPh3)3, P7(SiPh3)3, P7(SnMe3)3, P7(i-C3H7)3 and P7[Fe(CO)2Cp]3. Na3P7 reacts with Me3MCl (M  Si, Ge, Sn) yielding P7(MMe3)3. The reaction of Li3P7·3DME with PMe2Cl leads to P2Me4, but P7(PMe2)3 is not formed. Cleavage of the PSi bond in P7(SiMe3)3 by Me3SnBr or Me3SnCl gives the compounds P7(SiMe3)3-n(SnMe3)n with (n = 1, 2 or 3) depending on the molar ratio. The reaction with HI yields mixtures of H3-nP7(SiMe3)n,while I2 converts P7(SiMe3)3 into P2I4, PI3 and Me3SiI. Crystals of the Ge and Sn compounds are less sensitive towards oxidation and hydrolysis than P7(SiMe3)3. The compounds have been identified by 31P NMR and mass spectra. An X-ray structure analysis has shown P7(MMe3)3 (M = Si, Ge, Sn, Pb) to be isotypical (space group P21 (No. 4). The compounds crystallize as pure enantiomers. Bond lenghts and angles vary with their position in the P7 cage (PP = 222.2,218.8, and 218.0 pm) and are almost unaffected by the substitution. The PM bond lengths are 228.8 (Si); 235.5 (Ge); 253.9 (Sn); 261.7 pm (Pb), showing a small lengthening with respect to calculated values. The cone angle of the bridging P atom decreases with increasing size of M. The P7 cage vibrations are almost unchanged by the subsitution, whereas ν(PM) and ν(MC3) change in the usual manner.

Lattice dynamics of Hittorf's phosphorus and identification of structural groups and defects in amorphous red phosphorus

Abstract Using the force constants and bond polarisabilities of black phosphorus the dispersion, eigenvectors, and density of states for phonons, the sound velocity and the Raman spectra are calculated for polymeric violet Hittorfs phosphorus. Good agreement with Raman and Brillouin (v s,110,exp =6.95·10 5 cm s −1 ) measurements reported for the first time on oriented single crystals is found. Thus we are able to assign specific vibrational modes, such as extended wave-like vibrations and modes localised on the P 8 and P 9 structural subunits. Comparison with vibrational spectra of amorphous red phosphorus shows that the latter contains tubes similar to those of Hittorfs P. The absence of the group of lines (around 373 cm −1 ) due to P 8 cages in a-Pproves that the P 8 cages are present in much reduced numbers only there, or that the weaker bonds are broken or distorted. The features at 400 cm −1 and 455 cm −1 in a-P might be explained by the occurrence of P 7 cages. Broken P 8 units may also be the origin of the metastable intrinsic defects giving rise to the photo-induced ESR and axial luminescence centers in amorphous phosphorus.

New compounds with infinite chains of face-condensed octahedral Mo6 Clusters: InMo3Se3, InMo3Te3, TlMo3Se3 and TlMo3Te3

Abstract The ternary compounds M′Mo3X3 (M′ = In, Tl; X = Se, Te) are formed by reaction of the binary phases Mo3X4 with elemental M′ as well as from mixtures of M′X with molybdenum and X in sealed quartz ampoules (1300–1400 K). They are isostructural with TlFe3Te3 (space group P6 3 m , Z = 2 ; InMo3Se3, a = 883.5 pm, c = 449.2 pm; InMo3Te3, a = 932.6 pm, c = 459.0 pm; TlMo3Se3, a = 891.8 pm, c = 448.2 pm; TlMo3Te3, a = 942.8 pm, c = 458.3 pm). The structures are characterized by one-dimensional infinite 1∞ [Mo3X3] fibres which can be described as the end members of a structural series [Mo3nX3n+2] of condensed [Mo6X8] clusters.

Preparation, crystal structure, and ionic conductivity of digallium tribromide, Ga2Br3☆

Abstract Ga 2 Br 3 was prepared by reduction of GaBr 3 with Ga in sealed glass ampoules. Thermal behavior, Raman and mass spectra, ionic conductivity, as well as the crystal structure were investigated. Ga 2 Br 3 is the most metal-rich gallium bromide. According to X-ray results Ga 2 Br 3 is identical with the formerly described “GaBr.” The crystal structure has been solved on the basis of diffractometer data: orthorhombic space group Pnma ( a = 1253.7(7) pm, b = 1547.4(8) pm, c = 1253.4(5) pm, Z = 16). The structure contains pairwise associated ecliptic anions [Ga 2 Br 6 ] 2− with metal-metal single bonds. The coordination polyhedra around the three Ga + atoms are cubes and tricapped trigonal prisms of bromine atoms. A remarkable feature of the crystal structure is the vacancy in the Ga + partial structure, corresponding to the formulation Ga 4 □[Ga 4 Br 12 ]. They lead to Ga + ion conductivity with an activation enthalpy of 0.8 eV. The conductivity at 400 K is 1.5 × 10 −5 Ω −1 cm −1 . The material decomposes at 427 K.

Time-resolved photoluminescence of solid state fullerenes

Abstract Time-resolved photoluminescence studies in films, powders and single crystals of C60 are reported. The observed spectra in all forms are consistent with those reported for steady state conditions and may be associated with an intramolecular process. The spectrum is largely temperature independent and, at low temperatures, the observed luminescence decays with a lifetime of 1.2 ns. No long-lived decay from the triplet is observed at these intensities.In the case of the films, both the emission spectrum and lifetime are independent of excitation intensity. In the powder and single crystallite, a dramatic increase in the lifetime as well as a red-shift and broadening of the spectrum is observed at higher intensities. The luminescence intensity is seen to increase with the cube of the input intensity. The behaviour is interpreted as an abrupt onset of emission from the highly populated triplet state resulting from a banding of the intramolecular triplet states, a process which is dependent on a critical excited state density.

The orientational phase transition in C60 films followed by infrared spectroscopy

Abstract We have measured the infrared of C 60 films sublimed on gold from 25 to 300 K in the frequency range 15–5000 cm −1 . We observed several new lines emerging below 250 K which we assign to the infrared active modes of C 60 in the Pa 3 phase, based on the temperature dependence of these modes around the orientational phase transition. We compare our results with those obtained by other experimental methods and with theoretical predictions

BISMUT(II)-CHALKOGENOMETALLATE(III) BI2M4X8, VERBINDUNGEN MIT BI24+-HANTELN (M = AL, GA; X = S, SE)

Die ternaren Bismut(II)-chalkogenometallate(III) Bi2M4X8 mit M = Al, Ga und X = S, Se wurden aus den binaren Chalkogeniden M2X3 und Bi2X3 sowie elementarem Bismut synthetisiert. Alle Verbindungen sind diamagnetische Halbleiter mit Eg (opt.) = 1.8–2.7 eV. Sie sind bis auf Bi2Al4Se8 thermodynamisch stabil und zerfallen oberhalb 965–1020 K peritektisch. Bi2Al4Se8 ist unterhalb 825 K metastabil und kann nur durch rasches Abkuhlen von T > 825 K erhalten werden. Die Verbindungen sind isotyp und kristallisieren in einem neuen tetragonalen tP28-Strukturtyp (P4/nnc). Besonderes Merkmal ist das bisher unbekannte Clusterkation Bi24+ mit der mittleren Bindungslange d(Bi–Bi) = 314.2 pm, der Ramanfrequenz νs = 102–108 cm–1 und der Kraftkonstante f = 0.68 N · cm–1. Die Elektronenlokalisierungsfunktion (ELF) zeigt die kovalente Bindung der Bi2-Paare, die einsamen Elektronenpaare der ψ-oktaedrisch koordinierten Bi(II)-Kationen und den polaren Charakter der Bi–X-Bindungen. Bismuth(II) Chalcogenometallates(III) Bi2M4X8, Compounds with Bi24+ Dumbbells (M = Al, Ga and X = S, Se) The ternary bismuth(II) chalcogenometallates(III) Bi2M4X8 (with M = Al, Ga and X = S, Se) were synthesized from the binary chalcogenides M2X3 and Bi2X3 and elementary bismuth. All compounds are diamagnetic semiconductors with Eg (opt.) = 1.8–2.7 eV. The phases (except Bi2Al4Se8) are thermodynamically stable and decompose peritectically above 965–1020 K. Bi2Al4Se8 is metastable below 825 K and is obtained only by rapid quenching from T > 825 K. The isotypic compounds crystallize in a new tetragonal tP28 structure type (P4/nnc). The characteristic unit is the hitherto unknown clustercation Bi24+, with the mean bond length d(Bi–Bi) = 314.2 pm, the Raman frequency 102 cm–1 ≤ νs ≤ 108 cm–1, and the mean force constant of f = 0.68 N · cm–1. The Electron Localization Function, ELF, shows the covalent Bi–Bi bond, the lone electron pairs of the ψ-octahedrally coordinated Bi(II) cations, and the polar character of the Bi–X bonds.

Preparation, crystal structures, and electronic properties of LiGaCl3 and LiGaI3

LiGaCl3 and LiGaI3 have been prepared from LiX and GaX2 in sealed glass ampoules at 470 and 540 K, respectively. The crystal structures have been determined using single crystals (LiGaCl3: a = 1513.7(3) pm, b = 973.0(2) pm, c = 613.2(2) pm, Pnma, Z = 8; LiGaI3: a = 846.7(3) pm, b = 1137.2(3) pm, c = 713.2(2) pm, β = 91.77(5)°, P21m, Z = 4). LiGaCl3 is a new structure type, whereas LiGaI3 is isotypic to LiGaBr3. Both structures are characterized by eclipsed Ga2X6 units with d(GaGa) = 239.1 pm (chloride) and 242.8 pm (iodide). The arrangement of the trigonal prisms, (Ga2)X6, is similar to that in SrAg and GdFeO3 for the chloride and iodide respectively. The lengthening of the GaGa bond distance in the sequence Cl to I can be rationalized in terms of increasing population of the Ga2 σ∗ levels as the electronegativity of the anion decreases.

Thermische Zersetzung von CuInSe2, LiInSe2 und LiInTe2

The thermal decompositions of CuInSe2, LiInSe2 and LiInTe2 in vacuum at high temperatures were studied by using TG/DTG coupled with mass spectrometry. For CuInSe2, two steps were found to be significant. Up to 1000 °C Se2 and In2Se evaporate, followed later by Cu2Se. The Li-containing compounds show similar behaviour. However, Li+ was already detected during the first step. Obviously, Li2Se dissociates more readily than Cu2Se. No Cu+ species were detected up to the complete evaporation of CuInSe2.ZusammenfassungDie thermische Zersetzung von CuInSe2, LiInSe2 und LiInTe2 wurde mit TG/DTG - MS - - Kopplung bei hohen Temperaturen im Vakuum untersucht. Für CuInSe2 wurden zwei deutlich getrennte Stufen registriert. Bis 1000° verdampft Se und In2Se, später Cu2Se. Die Li-Verbindungen zeigen ähnliches Verhalten, jedoch wurde Li+ auch während der ersten Stufe nachgewiesen. Offenbar dissoziiert Li2Se eher als Cu2Se. Bis zur vollständigen Verdampfung von CuInSe2 erscheinen keine Cu+-Spezies in der Gasphase.РезюмеИспользуя ТГ/ДТГ, сопр яженные с масс-спектрометрией, изучено термическое разложение CuInSe2, LiInSe2 и LiInTe2 в в акууме при высоких температурах. Первое соединение разлагается в две ста дии: до температуры 1000° испаряется Se2 и In2Se, а зате м Си и Se. Литий содержащие соединен ия показали подобное поведение. Однако, уже на первой с тадии разложения был обнар ужен литий ион. Вероят но это обусловлено тем, что с еленид лития диссоциирует более л егко, чем селенид меди. Даже при полном разложении CuInSe2 н е было найдено ионов меди в п родуктах распада.

Die Kristallstruktur von Ga3Cl7/ Crystal Structure of Ga3Cl7

Abstract Trigallium heptachloride, G a3Cl7, has been prepared from GaCl3 and Ga in sealed glass ampoules. Ga3Cl7 crystallizes in the space group Pna21 (No. 33) with a = 1181.8(1) pm; b = 889.7(1) pm; c = 1057.5(1) pm; Z = 4. The compound is isotypic with KGa2Cl7-. The Ga2Cl7- anion has nearly C2 symmetry (gauche conformation) with d̄ (Ga -Clbridg) = 230.3 pm, d̄ (Ga -Clterm) = 214.3 pm and and ∢ Ga -Cl -Ga = 109.0°. The Ga+ ion is coordinated by ten Cl atoms (4 + 6) with d = 346.2 pm. The coordination of Ga+ and the conformation of Ga2Cl7- are discussed in detail together with related compounds.