[(Ph3PCH2)(Ph3P)PtCl][AlCl4], ein in CH2Cl2-lösung dreifach koordinierter kationischer platin(II)-komplex

The interaction of cis-[(Ph₃PCH₂)(Ph₃P)PtCl₂] with aluminium(III) chloride in CH₂Cl₂ affords the three coordinate cationic platinum(II) complex [(Ph₃PCH₂)(Ph₃P)PtCl][AlCl₄] which is a useful starting material for platinum complexes with four different ligands. With Ph₃As and Me₂S the cationic phosphorus ylide complexes [(Ph₃PCH₂)(Ph₃P)(Ph₃As)PtCl][AlCl₄] and [(Ph₃PCH₂)(Ph₃P)(Me₂S)PtCl][AlCl₄] are formed. 851 V 3     

An Enzyme-Labile Linker Group for Organic Syntheses on Solid Supports

Lipases and esterases can be used to fragment the 4-acetyloxybenzyloxy group used as a linker for organic synthesis on solid supports. (A support-bound compound is shown on the right; the enzyme-labile bond is marked with an arrow.) This enzyme-initiated fragmentation proceeds under very mild conditions (pH 6–7, room temperature), and the compounds of interest (amines, alcohols, carboxylic acids; X=NH, O, CR₂) constructed by combinatorial chemistry can be released with complete selectivity.     

Muonium spectroscopy

The electromagnetic interactions of electrons and muons can be described to very high accuracy within the framework of standard theory, in particular within the hydrogen like muonium atom. Therefore, precision measurements are able to test basic interactions in physics and to search for yet unknown forces. Accurate values for fundamental constants can be obtained. Results from experiments on the ground state hyperfine structure and the 1s–2s intervals in muonium are described together with their relations to a new measurement of the muon magnetic anomaly. This revised version was published online in August 2006 with corrections to the Cover Date.     

g-2 of the Muon

The experimental value a $_{\mu}^{\rm exp}$ for the muon magnetic anomaly measured at the Brookhaven National Laboratory (BNL), Upton, USA, and the latest theoretical value a $_{\mu}^{\rm theo}$ based on a number of calculations and auxiliary experiments differ today by 3.3 standard deviations. Discrepancies between different independent approaches towards the theoretical value could recently be removed and had yielded a consistent value for a $_{\mu}^{\rm theo}$ . At the Fermi National Laboratory (Fermilab), Batavia, USA, a new experiment has been approved which aims to improve the present experimental uncertainty by a factor of about five. At this level the muon magnetic anomaly is superior in sensitivity to, e.g., LHC concerning tests of several speculative models beyond standard theory. The new experiment relies in the essential parts on concepts proven at BNL such as a muon storage ring at 1.45 T field to store muons at 3.1 GeV/c momentum and field magnetometry based on NMR in water. At Fermilab predominantly a significantly higher number of muons can be exploited.     

Measurement of the positive muon anomalous magnetic moment to 0.7 ppm

A higher precision measurement of the anomalous g value, a(mu)=(g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron, based on data collected in the year 2000. The result a(mu(+))=11 659 204(7)(5)x10(-10) (0.7 ppm) is in good agreement with previous measurements and has an error about one-half that of the combined previous data. The present world average experimental value is a(mu)(expt)=11 659 203(8)x10(-10) (0.7 ppm).