The role of dispersion type metalπ interaction in the enantiotropic phase transition of two polymorphs of tris-(thienyl)bismuthine.

Two polymorphs of tris(thienyl)bismuthine Bi(2-C4H3S)3 (1) were isolated upon crystallization from n-hexane at different temperatures. The high temperature form 1-HT crystallized at 269 K in the trigonal space group R3[combining macron], whereas the low temperature form 1-LT crystallized at 245 K in the triclinic space group P1[combining macron]. An enantiotropic phase transition was observed at 250 K showing a transition energy of 1.4 kJ mol-1. Both polymorphs reveal the formation of centrosymmetric dimers that are based on London dispersion type bismuthπ heteroarene interactions. These primary building units show additional dispersion type interactions between neighbouring dimers and as a result 2D networks are formed. DFT calculations on the model systems BiX3π thiophene (X = Cl, Me) verify the hypothesis of a soft and shallow binding potential of the London dispersion type bismuthπ heteroarene interaction, providing an explanation for the reversibility of the phase transition.

Heteroaryl bismuthines: a novel synthetic concept and metalπ heteroarene interactions.

The alkoxide Bi[OCMe2(2-C4H3S)]3 (1) is formed by the reaction of three equiv. of the alcohol HOCMe2(2-C4H3S) with Bi(OtBu)3 and subsequent hydrolysis provides the bismuth oxido cluster [Bi4O2{OCMe2(2-C4H3S)}8] (2). In contrast, the reaction of Bi(OtBu)3 and Bi[N(SiMe3)2]3 with the silanols HOSiMe2(2-C4H3X) (X = O, S, Se, and NMe), HOSiMe2(2-C4H2S-5-SiMe3) and HOSiMe2(3-C4H3S) leads to the formation of tris(heteroaryl)bismuthines Bi(2-C4H2X-5-R)3 [where X = O, R = H (3); X = S, R = H (4); X = S, R = SiMe3 (5); X = NMe, R = H (6); X = Se, R = H (7)] and Bi(3-C4H3S)3 (8). For the silanols, bismuth-carbon bond formation is observed rather than silanol-alcoholate or silanol-amide exchange. The structures of compounds 1, 2, and 4-7a in the solid state were established by single crystal X-ray diffraction and all compounds except 5 show London dispersion type bismuthπ heteroarene interactions. For the bismuthine Bi(2-C4H3Se)3 (7), two polymorphs were isolated depending on the conditions of crystallization. At 8 °C, polymorph I (7a) crystallizes from an n-hexane solution in the triclinic space group P1[combining macron], whereas polymorph II (7b) crystallizes at 20 °C from a CH2Cl2/n-pentane solution in the monoclinic space group P21/c. The heteroaryl bismuthines 3 and 4 exhibit 2D network structures as a result of bismuthπ heteroarene interactions, whereas for the pyrrole derivative 6 the dispersion type interactions provide separated dimers.

Hydrolysis studies on bismuth nitrate: synthesis and crystallization of four novel polynuclear basic bismuth nitrates.

Hydrolysis of Bi(NO(3))(3) in aqueous solution gave crystals of the novel compounds [Bi(6)O(4)(OH)(4)(NO(3))(5)(H(2)O)](NO(3)) (1) and [Bi(6)O(4)(OH)(4)(NO(3))(6)(H(2)O)(2)]·H(2)O (2) among the series of hexanuclear bismuth oxido nitrates. Compounds 1 and 2 both crystallize in the monoclinic space group P2(1)/n but show significant differences in their lattice parameters: 1, a = 9.2516(6) Å, b = 13.4298(9) Å, c = 17.8471(14) Å, ß = 94.531(6)°, V = 2210.5(3) Å(3); 2, a = 9.0149(3) Å, b = 16.9298(4) Å, c = 15.6864(4) Å, ß = 90.129(3)°, V = 2394.06(12) Å(3). Variation of the conditions for partial hydrolysis of Bi(NO(3))(3) gave bismuth oxido nitrates of even higher nuclearity, [{Bi(38)O(45)(NO(3))(24)(DMSO)(26)}·4DMSO][{Bi(38)O(45)(NO(3))(24)(DMSO)(24)}·4DMSO] (3) and [{Bi(38)O(45)(NO(3))(24)(DMSO)(26)}·2DMSO][{Bi(38)O(45)(NO(3))(24)(DMSO)(24)}·0.5DMSO] (5), upon crystallization from DMSO. Bismuth oxido clusters 3 and 5 crystallize in the triclinic space group P1 both with two crystallographically independent molecules in the asymmetric unit. The following lattice parameters are observed: 3, a = 20.3804(10) Å, b = 20.3871(9) Å, c = 34.9715(15) Å, α = 76.657(4)°, ß = 73.479(4)°, γ = 60.228(5)°, V = 12021.7(9) Å(3); 5, a = 20.0329(4) Å, b = 20.0601(4) Å, c = 34.3532(6) Å, α = 90.196(1)°, ß = 91.344(2)°, γ = 119.370(2)°, V = 12025.8(4) Å(3). Differences in the number of DMSO molecules (coordinated and noncoordinated) and ligand (nitrate, DMSO) coordination modes are observed.

Electronic states and the influence of oxygen addition on the optical absorption behaviour of manganese phthalocyanine.

The effects of electronic states and air exposure on the spectroscopic properties of manganese phthalocyanine (MnPc) have been examined. The observed features of the Q-band in the absorption spectra can be explained by intrinsic electronic properties of MnPc, i.e., the formation of singly charged molecules by charge transfer excitations. However, the reaction of MnPc with atmospheric molecular oxygen leads to deviations in peak intensities but does not change the fundamental characteristics of the spectra. Nevertheless, the reaction with oxygen changes the spin state from S = 3/2 to S = 1/2. X-ray diffraction measurements also indicate a slow diffusion process of the oxygen into the MnPc crystal. We discuss both influences to explain the behaviour of MnPc in various spectroscopic methods (EELS, ellipsometry, PES). Furthermore, we support the experimental investigations by detailed ab-initio calculations of spectroscopic properties using methods of the density functional theory framework.

Indirect detection of selective nuclear spin-spin interactions in a hostile environment.

We present a number of techniques which may be used to obtain precise values of selective spin-spin interactions between two nuclear spins in a hostile environment. Such an environment may be characterized by very fast relaxation and decoherence, e.g. due to the strong coupling of the two spins of interest to electron spins in their vicinity as well as other nuclei. Here, we used dilute paramagnetic Ce(3+) centers hosted in a single crystal of CaF(2). Selected (19)F internuclear interactions were measured indirectly by applying different electron nuclear double resonance (ENDOR) pulse sequences.

Pseudoentanglement of spin states in the multilevel 15N@C60 system.

We have prepared combined electron and nuclear spin pseudoentangled states Psi+/-27 and Phi+/-18 out of the total number of eight quantum states in the multilevel quantum system of a nitrogen atom with electron spin 3/2 and nuclear spin 1/2 encaged in the endohedral fullerene (15)N@C(60). Density matrix tomography was applied to verify the degree of entanglement.

Entanglement between an electron and a nuclear spin 1/2.

We report on the preparation and detection of entangled states between an electron spin 1/2 and a nuclear spin 1/2 in a molecular single crystal. These were created by applying pulses at ESR (9.5 GHz) and NMR (21 MHz, 46 MHz) frequencies. Entanglement was detected by using a special entanglement detector sequence based on a unitary back transformation including phase rotation.

[Prognostic factors for development of peritoneal carcinosis in stomach carcinoma]. / Prognosefaktoren für das Auftreten einer Peritonealcarcinose beim Magencarcinom.

OBJECTIVE: Several adjuvant therapy concepts have been developed to improve the treatment of gastric cancer patients. Dealing with intraperitoneal chemotherapy, it seems to be useful to determine suitable prognostic factors for the occurrence of peritoneal carcinosis, as it is possible to select patients who may profit from this therapy. METHODS: Between June 1975 and December 1999 resection of gastric cancer was performed in 575 patients. From 1 January 1986 clinical data were recorded prospectively, before that time, retrospectively. The complete data concerning preoperative diagnosis, operation, histology, postoperative course and survival time were documented in an Excel file for statistical analysis. Multivariate analysis was performed using the chi-squared logistic regression test. RESULTS: Significant correlation was found between the occurrence of peritoneal dissemination and tumour stage pT3, pN2, G3, cancer of the whole stomach and cancer at the anastomotic site after partial gastric resection. Lauren classification, signet-ring cell cancer, liver metastasis and tumour localisation in the distal or proximal stomach showed no significant correlation to peritoneal carcinosis in the multivariate analysis. However, only one-third of patients with liver metastasis had simultaneous peritoneal dissemination. CONCLUSION: The results show a clinical correlation of tumour localisation, infiltration of the serosa, lymph node metastasis and grading with peritoneal dissemination. The present data serve as a basis for further histochemical and molecular biological investigations e.g. of the expression of adhesion molecules to determine the risk of peritoneal tumour dissemination after gastric cancer.

The first bismuth phosphonate cluster. X-ray single crystal structure of [(ButPO3)10(ButPO3H)2Bi14O(10).3C6H(6).4H2O].

The reaction of triphenylbismuth and tert-butylphosphonic acid gives the bismuth phosphonate phase (ButPO3H)3Bi and the first bismuth phosphonate cluster [(ButPO3)10(ButPO3H)2Bi14O(10).3C6H(6).4H2O].

Electron spin density distribution in the polymer phase of CsC60: assignment of the NMR spectrum.

We present high resolution 133Cs-13C double resonance NMR data and 13C-13C NMR correlation spectra of 13C enriched samples of the polymeric phase of CsC60. These data lead to a partial assignment of the lines in the 13C NMR spectrum of CsC60 to the carbon positions on the C60 molecule. A plausible completion of the assignment can be made on the basis of an ab initio calculation. The data support the view that the conduction electron density is concentrated at the C60 "equator," away from the interfullerene bonds.

Charge-order-driven spin-peierls transition in alpha(')-NaxV2O5

We conclude from 23Na and 51V NMR measurements in alpha(')-NaxV2O5 (x = 0.996) (i) a charge-ordering transition starting at T

Production of volatile derivatives of metal(loid)s by microflora involved in anaerobic digestion of sewage sludge.

Gases released from anaerobic wastewater treatment facilities contain considerable amounts of volatile methyl and hydride derivatives of metals and metalloids, such as arsine (AsH(3)), monomethylarsine, dimethylarsine, trimethylarsine, trimethylbismuth (TMBi), elemental mercury (Hg(0)), trimethylstibine, dimethyltellurium, and tetramethyltin. Most of these compounds could be shown to be produced by pure cultures of microorganisms which are representatives of the anaerobic sewage sludge microflora, i.e., methanogenic archaea (Methanobacterium formicicum, Methanosarcina barkeri, Methanobacterium thermoautotrophicum), sulfate-reducing bacteria (Desulfovibrio vulgaris, D. gigas), and a peptolytic bacterium (Clostridium collagenovorans). Additionally, dimethylselenium and dimethyldiselenium could be detected in the headspace of most of the pure cultures. This is the first report of the production of TMBi, stibine, monomethylstibine, and dimethylstibine by a pure culture of M. formicicum.

Syntheses, characterizations, and single-crystal X-ray structures of soluble titanium alkoxide phosphonates.

Reactions of Ti(OiPr)4 with different phosphonic acids RPO3H2 (R = Ph, 4-CNPh, Me, tBu) in organic solvents have been investigated. In the presence of small amounts of water, the new molecular titanium oxide alkoxide phosphonates [Ti4(mu 3-O)(OiPr)5(mu-OiPr)3(RPO3)3].DMSO [R = Ph (1), Me (2), tBu (3), 4-CNPh (4)] were isolated. The single-crystal X-ray structure analyses of 1 and 2 revealed hexacoordinated titanium atoms and a connectivity of (111) for each phosphonate. Under rigorous exclusion of water, the reaction of Ti(OiPr)4 with tert-butylphosphonic acid in toluene gave the titanium phosphonate tetramer [Ti(OiPr)2(tBuPO3)]4 (5). A single-crystal X-ray structure analysis of 5 revealed a 5 + 1 coordination of the titanium atoms as a result of the (112) connectivity of each phosphonate; such a coordination mode has never been reported for a titanium phosphate, phosphonate, or phosphinate. Compounds 1-5 were characterized by FT-IR, 31P MAS NMR, and solution multinuclear NMR (1H, 13C(1H,) 31P(1H)) spectroscopies. 13C CP MAS NMR experiments were carried out on arylphosphonates 1 and 4. Solution NMR experiments were also used to investigate the exchange reaction between 1 and 2 and the conversion of 5 to [Ti4(mu 3-O)(OiPr)5(mu-OiPr)3(tBuPO3)3].iPrOH by partial hydrolysis in the presence of Ti(OiPr)4. The phosphonate clusters 1-5 are soluble in organic solvents and are likely intermediates in the sol-gel processing of inorganic-organic hybrids based on titanium oxide and phosphonate groups that we are currently developing.