The synthesis and molecular structure of 1-(η5-cyclopentadienyl)-1-triphenylphosphine-2,3,4,5-tetrakis(pentafluorophenyl)rhodole

A reaction between π-cyclopentadienylcarbonyl(triphenylphosphine)rhodium and bis(pentafluorophenyl)acetylene in refluxing xylene has produced low yields of hexakis(pentafluorophenyl)benzene and 1-(η⁵-cyclopentadienyl)-1-triphenylphosphine-2,3,4,5-tetrakis(pentafluorophenyl)rhodole. The metallocycle has been characterized by elemental analysis, spectral measurements and an X-ray diffraction study. Yellow crystals of the title compound from Skelly C are triclinic with a 11.715(4), b 14.015(6), c 20.420(6) Å and α 114.07(3), β 106.97(3), γ 107.28(3)°. The space group indicated by intensity statistics is P1, and there are two molecules per unit cell. An ill-defined solvent molecule in the cell affects the agreement between the observed and calculated densities. A similar solvation was observed in the corresponding cobaltacycle which is isomorphous with the rhodium complex. The final residual R after least-squares refinement was 0.065 for the 5235 reflections with I$\text{\$}\text{?}$2σ(I) which were used in the analysis. The rhodium is σ-bonded to the two carbons of the butadiene-like fragment with Rh—C bonds of 2.060(12) and 2.067(11) Å. The C—C distances of 1.343(16), 1.457(16) and 1.354(15) Å indicate that the C₄fragment is very similar to a butadiene group. The Rh—P distance of 2.293(2) Å is longer than the value of 2.234(3) Å found in the cobaltacycle, which is consistent with the larger size of Rh compared to Co.     

Cross-validation and evaluation of the performance of methods for the elemental analysis of forensic glass by μ-XRF, ICP-MS, and LA-ICP-MS

Elemental analysis of glass was conducted by 16 forensic science laboratories, providing a direct comparison between three analytical methods [micro-x-ray fluorescence spectroscopy (μ-XRF), solution analysis using inductively coupled plasma mass spectrometry (ICP-MS), and laser ablation inductively coupled plasma mass spectrometry]. Interlaboratory studies using glass standard reference materials and other glass samples were designed to (a) evaluate the analytical performance between different laboratories using the same method, (b) evaluate the analytical performance of the different methods, (c) evaluate the capabilities of the methods to correctly associate glass that originated from the same source and to correctly discriminate glass samples that do not share the same source, and (d) standardize the methods of analysis and interpretation of results. Reference materials NIST 612, NIST 1831, FGS 1, and FGS 2 were employed to cross-validate these sensitive techniques and to optimize and standardize the analytical protocols. The resulting figures of merit for the ICP-MS methods include repeatability better than 5 % RSD, reproducibility between laboratories better than 10 % RSD, bias better than 10 %, and limits of detection between 0.03 and 9 μg g^?1 for the majority of the elements monitored. The figures of merit for the μ-XRF methods include repeatability better than 11 % RSD, reproducibility between laboratories after normalization of the data better than 16 % RSD, and limits of detection between 5.8 and 7,400 μg g^?1. The results from this study also compare the analytical performance of different forensic science laboratories conducting elemental analysis of glass evidence fragments using the three analytical methods.

2-Chloro-3H-indol-3-one and its reactions with nucleophiles

The title compound reacts with N- and S-nucleophiles to form 3-substituted indol-2-ones, but with C-nucleo-philes to afford either these or the corresponding 2-substituted indol-3-ones. This dichotomy of behavior is documented and rationalized.     

Structural studies of antihistamines. The crystal structure ofH 4aH 9a -cis-H 9,H 9a-trans-2-methyl-9-phenyl-2, 3,4,4a,9,9a-hexahydro-1H-indeno[2,1-c]pyridine hydrochloride

The crystal and molecular structure ofH _4a ,H _9a -cis-H ₉,H _9a -trans-2-methyl-9-phenyl-2, 3,4,4 _a ,9,9 _a -hexahydro-1H-indeno[2,1-c]pyridine hydrochloride was determined. The compound crystallizes in the orthorhombic space groupPbca, with eight molecules in the unit cell of dimensionsa = 10.461(2),b = 20.141(10), andc = 15.469(3) Å. Intensity data were measured using Mo radiation and a – scan method. The structure was solved by direct methods and refined by least-squares techniques to a finalR of 4.6%. Thecis-trans isomer has higher antihistamine activity compared to thecis-cis isomer but is less active than phenindamine, the 2,3,4,9-tetrahydro derivative. The bond distances in thecis-trans andcis-cis derivatives are identical so that the differences in activity must be related to differences in conformation. The difference in the conformation is discussed from a receptor-site view of the two molecules.