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The reaction of As4Se4 with stoichiometric amounts of [Cp*Fe2(CO)4] (Cp* = C5Me5) in boiling toluene forms [Cp2*Fe2As2Se2] (1) in good yield. X-ray crystallography shows 1 to have a triple-decker structure which comprises a tetraatomic mu,eta4:4-As2Se2 ligand. Density functional theory (DFT) and extended Hückel molecular orbital (EHMO) calculations confirm that the As2Se2 ligand behaves as a four-electron pi donor. Oxidation of 1 with equimolar amounts of [(C5H5)2Fe]PF6, Br2 and I2, respectively, gave compounds 2-4. According to X-ray crystallographic investigations that were carried out on 2 and 4, the oxidation state has a considerable influence on the structure of the Fe2As2Se2 core: significant shortening of the Fe-Fe distance (deltad(Fe-Fe)> 0.3 A) and weakening of the As-As bond length ((deltad(As-As) > 0.3 A) suggests the formal presence of two diatomic AsSe ligands and a Fe-Fe bond. DFT and EHMO calculations confirm that an electron is removed from an occupied Fe-Fe orbital of antibonding character during oxidation. All molecular orbitals lower their energies upon oxidation, but the energy drop is relatively small for those involving the As-As bond. An additional structural feature in 4 consists of an electronic interaction of the iodide with both As atoms which suggests a formally neutral ion pair. Electrochemical studies confirm that the oxidation of 1 is a reversible one-electron process with E(1/2)= +0.07 V (in THF). These studies also reveal that 4 dissociates in polar solvents, such as THF, into [1]+ and I-, which is followed by transformation into 1 and I3.

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The syntheses and the electrochemical behavior of the monomeric peralkylated hexaamino(1,3)metacyclophane 4, the dimeric dodecaamino(1,3)cyclophane 5a, and the dodecaamino(1,3,5)cyclophane 6 are described. Electrochemical measurements show that the hexaaminobenzene units in 4 and 5a undergo an unusually slow two-electron transfer attributed to the deformation of the rings into bis-cyanine cations when oxidized to the respective dication. Further oxidations to tri-, tetra-, and hexacationic units occur at more positive potentials. In the dimeric structures, no interaction between the rings can be seen in the (1,3)cyclophane, but strong interaction for the (1,3,5)cyclophane is observed.

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Abstract: The reaction of [Cp#2NbTe2H] (1#; Cp# = Cp* (C5Me5) or Cp(x) (C5Me4Et)) with two equivalents of [Co2(CO)8] gives a series of cobalt carbonyl telluride clusters that contain different types of niobocene carbonyl fragments. At 0 degrees C, [Cp#2NbTe2CO3(CO)7] (2#) and [Co4Te2(CO)10] (3) are formed which disappear at higher temperatures: in boiling toluene a mixture of [cat2][Co9Te6(CO)8] (5#) (cat= [Cp#2Nb(CO)2]+) and [cat2][Co11Te7(CO)10] (6#) is formed along with [cat][Co(CO)4] (4#). Complexes 6# transform into [cat][Co11Te7(CO)10] (7#) upon interaction with HPF6 or wet SiO2. The molecular structures of 2(Cp(x)), 4(Cp(x)), 5(Cp*), 6(Cp*) and 7(Cp*) have been determined by X-ray crystallography. The structure of the neutral 2(Cp(x)) consists of a [Co3(CO)6Te2] bipyramid which is connected to a [(C5Me4Et)2Nb(CO)] fragment through a mu4-Te bridge. The ionic structures of 4(Cp(x)), 5(Cp*), 6(Cp*) and 7(Cp*) each contain one (4, 7) or two (5, 6) [Cp#2Nb(CO)2]+ cations. Apart from 4, the anionic counterparts each contain an interstitial Co atom and are hexacapped cubic cluster anions [Co9Te6(CO)8]2- (5) or heptacapped pentagonal prismatic cluster anions [Co11Te7(CO)10]n- (n=2: [6]2- , n=1: [7]-), respectively. Electrochemical studies established a reversible electron transfer between the anionic clusters [Co11,Te7(CO)10]- and [Co11Te7(CO)10]2in 6# and 7# and provided evidence for the existence of species containing [Co11Te7(CO),0] and [Co11Te7(CO)0]3-. The electronic structures of the new clusters and their relative stabilities are examined by means of DFT calculations.

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In a clinical trial the accuracy of volumetry by use of three-dimensional ultrasound (3-D-US) in comparison to three-dimensional computer tomography (3-D-CT) was evaluated. Overall, 42 patients with focal hepatic lesions were investigated with 2-D- and 3-D ultrasound. In 11 patients additional computerized tomographic arterial portography using spiral technique was performed. The volumes of the lesions were calculated using the ellipsoid formula (for 2-D- and 3-D-US) as well as with a planimetric reconstruction for 3-D-US and 3-D-CT. In addition the intra- and inter-investigator variability of 3-D ultrasound was determined. The volume of the investigated liver lesions (planimetric reconstruction with 3-D ultrasound) ranged between 1.5 cm3 and 1231 cm3 with a mean volume of 155 cm3 and a median volume of 68 cm3. The deviation of 2-D-US vs 3-D-CT was -62% to +68%, in the case of 3-D-US (ellipsoid) vs 3-D-CT it was -28% to +9%, and for 3-D-US (planimetry) vs 3-D-CT it was -21% to +9%. The concordance index kappa was 0.886, showing very good agreement between the two investigators. The intra-investigator variability was 5%. Our data show that volume measurement by use of 3-D-US in independent of the investigator. With regard to accuracy of volume measurements 3-D-US is comparable to 3-D-CT but more precise than 2-D-US. These results indicate that 3-D-US may be applied in the follow-up of tumor patients as an alternative diagnostic procedure to computer tomography. In addition 3-D-US might be useful in planning liver resections by virtue of better evaluation of the volume of the liver tissue remaining after resection and better visualization of the topography of liver tumors and major hepatic vessels.

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AIM: The use of a new 3D ultrasound system should reduce the drawbacks of former 3D workstations (long image generation time, limited use due to the need for special 3D transducers), so that it is now applicable in daily clinical routine. METHOD: An ultrasound 3D workstation was used based on a pentium PC platform, employing a magnetoelectronic position detection system for spatial reconstruction of conventional 2D B-scan image sequences. RESULTS: Better assessment of topographico-anatomical spatial relationships was achieved when presenting pathological findings, especially in assessing lymph nodes and salivary stones. Pathological processes in the maxillofacial area occurring during a period of five months were visualised. CONCLUSION: The method of 3D reconstruction of standard two-dimensional electronic scans, as presented here, is the first method of its kind enabling applicability in daily clinical routine thanks to rapid imaging. The images can be produced with any ultrasound unit or transducer. First clinical results in maxillofacial surgery clearly show improved diagnostic possibilities although there still room for an improvement of the image quality. The possibility of semi-automatic exact volumetry appears meaningful especially in the investigation of lymph nodes. Integration of colour duplex sonography will further enhance the diagnostic value of this method.

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The use of a digital image processing system in ultrasound diagnostics offers not only the advantage of a space-saving archiving without loss of quality, but also a clearly higher efficacy of the examination is achieved. An interactive of system findings leads to a more complete examination and evaluation, thus increasing the reliability and the objectivity of the examination. The standardized findings by use of text components mean at the same time a clear saving of time. Moreover, this system is very comfortable not only for the comparison of different images, but also for the scientific evaluation and processing of the image data. By digitalizing the sonographic images the visual data can be processed in a personal computer. Thereby, for maxillofacial surgery a simple and fast dynamic-functional evaluation of the temporomandibular joint was made possible. By archiving without loss of quality and by higher reliability, objectivity and efficacy of the sonographic examination important preconditions for quality care in ultrasound diagnostics have been achieved.

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The reactions of bismuth(III) nitrate pentahydrate and bismuth(III) chloride with heterocyclic thiosemicarbazones and derivatives of dithiocarbazonic acid methylester were used to synthesize the respective bismuth(III) complexes, which could be divided into five groups D-H because of their stoichiometrical properties and their molecular structures. The molecular structure and the near coordination sphere of the bismuth(III) central atom of four representative compounds were determined by single-crystal X-ray studies. Bis[1-azepanyl-4-(2-pyridyl)-2,3-diazapenta-1,3-diene-1-thiolato-N',N(3),S]bismuth(III) nitrate (5) belongs to group D. The two tridentate ligands and the nitrate ion surround the bismuth atom. The best description of the coordination sphere appears to be that of a distorted trigonal dodecahedron with one position occupied by the lone pair of the bismuth atom. Bis[1-azepanyl-4-(2-thienyl)-2,3-diazapenta-1,3-diene-1-thiolato-N(3),S]bismuth(III) nitrate (9) is assigned to complex type E. Here, two deprotonated ligand molecules are coordinated to the bismuth(III) central atom as bidentate ligands. The structure of this complex can best be described as a distorted trigonal antiprism with a five-coordinated central atom. The two triangular faces are formed by the atoms S(4), N(6), O(11) and S(3), N(4) and the lone pair of the central atom. The two chelate rings are almost perpendicular to each other. Complex molecules of group F form dimeric units with bichloro-bridged bismuth atoms. The structure of di-mu-chlorobis[1-azepanyl-4-(2-pyridyl)-2,3-diazapenta-1,3-diene-1-thiolato-N',N(3),S-chloro]dibismuth(III) (15) can be described as two six-coordinated bismuth atoms, which are bound together via two bridging chlorine atoms. The two bismuth atoms Bi(1) and Bi(1a) and the two bridging chlorine atoms Cl(2) and Cl(2a) form the Bi(2)Cl(2) plane. The two tridentate ligand molecules coordinate via the same atoms as shown in complex 5. In addition, they form two parallel planes, which are perpendicular to the Bi(2)Cl(2) plane. With regard to the center of the Bi(1)-Bi(2) axis they are central point symmetrical, i.e. one pyridine ring lies above and the other beneath the Bi(2)Cl(2) plane. Bismuth(III) chloride and pyridine-2-carboxaldehydethiosemicarbazone 1 b or 2-acetylpyridine-thiosemicarbazone 1 c form complexes of group G. Three chlorine atoms and a bidentate ligand are coordinated to the bismuth(III) central atom. The bidentate ligand bound to the central atom through the N(3) atom and the sulfur atom of the thioketo group. The structure of 18 is completely different from the structures of the bismuth(III) complexes discussed so far and was therefore assigned to group H. The bismuth central atom is coordinated with two ligands, which are bound in different ways. One of them is deprotonated. This ligand is bound to the central atom via the sulfur atom S(3) of the thiolate group and the N(5) atom. An interaction between the sulfur atom of the thiophene ring and the bismuth atom is not possible.The other ligand molecule is not deprotonated. This ligand is bound to the bismuth(III) cation merely via the sulfur atom S(1) of the thioketo group. The best description of the coordination sphere of the bismuth atom is that of a distorted square bipyramidal polyhedron. The square face is formed by the atoms S(3), N(5), Cl(1), the lone pair and the bismuth atom within. The axial positions are occupied by the atoms S(1) and Cl(2). The bond angle between S(1), Bi(1) and Cl(2) differs by about eight degrees from the value determined for a regular square bipyramidal polyhedron of 180 degrees.Some of the newly synthesized bismuth complexes and three ligands have been tested against several strains of Helicobacter pylori bacteria in an agar dilution test. Almost all of the listed bismuth complexes show excellent inhibitory properties with regard to growth of H. pylori already at low concentrations.

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A three-dimensional (3D) workstation for data acquisition, processing, registration and presentation of 3D ultrasound information is described. The ultrasound images needed for further processing are generated by a standard diagnostic ultrasound system. The 3D transducers used here include frequencies of 3.5, 5 and 7.5 MHz. The presentation of reconstructed 3D data is performed by computer-assisted projection of volumetric data or by the presentation of user-selectable slices from the 3D object. Besides improved diagnosis of 3D structures, the system enables precise volume measurements.

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The elucidation of the structure of gypsetin, a new inhibitor of acyl-CoA: cholesterol acyltransferase, is described in this paper. By spectroscopic and X-ray crystallographic analyses, the structure of gypsetin has been determined to be 8a,16a-dihydroxy-5a,13a-bis[1,1-dimethylallyl]-[1]benzazolidine [3''' 2''':4'',5'']azolidino[1'',2'':4',5'][1,4]perhydrodiazin[1', 2':1, 5]azolidino[2,3-b]-[1]benzazolidine-7,15-dione.

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The structural features of a new class of non-nucleoside HIV-1 reverse transcriptase inhibitors (3) are presented. Comparison of the structural and electronic properties with those of TIBO (1) and Nevirapine (2) yields a common three-dimensional model. This model permits the improvement of the lead compound 3 by chemical modification (5,6). Additionally, two new types of inhibitors (4, 7) with similar biological activity can be derived from this model. The structure of the new compounds, including their absolute configuration, are determined by X-ray crystallography.

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Three-dimensional reconstruction of an organ requires a coordinated sequence of cross-sectional scans. In ultrasound this can be solved by rotating the scan plane horizontally or vertically. Two scan heads have been built, one to rotate the plane around a horizontal, the second around a vertical axis. There are two ways to reconstruct the scans taken by ultrasound into a three-dimensional image: --to contour the surface of the organ in each scan and to reconstruct these contours to a ring-shaped structure. This procedure needs a lot of time; moreover, contouring must be performed via cursor on the screen. --calculate a transparent image of the organ. To obtain the best spatial image by the "transparent method", the image must be moved on the screen. Both methods of reconstruction are shown and compared in this paper. First experiences show that they can be applied in tumour diagnostic and in the diagnosis of malformations in early pregnancy. Further clinical studies will have to prove this.

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The problem of gaining a coordinated sequence of section cuts by ultrasound is solved by rotating the plane section around a vertical and a horizontal axle. There are two possibilities in presenting the 3D image of the examined organ: ring structure image or transparent image. Precondition in the ring structure image is time consuming and defective since it has to be done by hand using a cursor. These pitfalls can be avoided when using a method without contouring by showing the 3D image transparently. Each section cut has to be calculated transparently. Both methods are presented in this paper and compared as to their applicability in medicine. The problem of the transparent 3D presentation lies in the fact that it cannot be well presented on printed paper, as is done her. The moving picture on the computer screen gives an optimal 3D image. This new method seem to be useful in tumor diagnostic and diagnostic of malformations in early pregnancies.

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