Numerical integration for the real time production of fundamental ephemerides over a wide time span

A simplified model of the solar system has been developed along with an integration method, enabling to compute planetary and lunar ephemerides to an accuracy better than 1 and 2 milliarcsecs, respectively. On current personal computers, the integration procedure (SOLEX) is fast enough that by using a relatively small (similar to 20 Kbytes/Cy) database of starting conditions, any epoch in the time interval (up to +/-100 Cy) covered by the database can be reached by the integrator in a few seconds. This makes the algorithm convenient for the direct computation of high precision ephemerides over a time span of several millennia

Electrophilicity of coordinated carbon monoxide in alkoxydienylplatinum(II) carbonyl complexes. Synthesis of (diene)platinum(II) alkoxycarbonyl complexes

If alkoxydienyl complexes of the type [Pt(dieneOR)Cl]2 are allowed to react with carbon monoxide under mild conditions, unstable carbonyl complexes are formed. The carbonyl complexes may react with an alcohol to give alkoxycarbonyl complexes of the type (diene)PtClCOOR. This reaction involves nucleophilic attack of alcohol on the coordinated carbonyl group, and expulsion of the alkoxyl group from the dienyl moiety with formation of a coordinated carboncarbon double bond. This reaction, however, is not of general occurrence. A comparison is made between the electrophilicities of coordinated carbon monoxide and coordinated carboncarbon double bond. © 1974

Model ligands for copper proteins. Proton magnetic resonance study of acetylhistamine and acetylhistidine complexes with copper(I)

The complexes (acetylhistamine)2copper+ and (acetyl-L-histidine)2copper+ have been studied in aqueous solutions by means of proton magnetic resonance spectroscopy. The amide group proved to be unable to complex Cu+ both alone and in conjunction with the nonspecific imidazole ligand. The Cu2+ specific carboxylate group, on the other hand, appears to be a possible site of coordination also for Cu+ when coupled with the imidazole ligand. These results are interpreted with respect to the problem of the active site of copper proteins with redox activity

Intermolecular Cross-coupling between 2-Olefin and 1-Allyl Ligands in Cationic Platinum(II) and Palladium(II) Complexes

The n1-allyl platinum and palladium cationic complexes tridentate neutral pincer ligand [(PNP)M(n1-CH2CH=CHR1)]+ (1, PNP = 2,6-bis-diphenylphosphinomethylpyridine) undergo intermol. attack of the terminal gamma-carbon atom of the allyl system at the coordinated olefin of dicationic platinum and palladium complexes [(PNP)M(n2-CH2=CHR)]2+ (2), producing binuclear species [(PNP)M(n2:n1-CH2=CHCHR1CHRCH2)M(PNP)]3+ (4), in which the metal formerly p-coordinated becomes s-bonded, and the metal formerly s-bonded becomes p-coordinated. The reaction can be run catalytically with respect to the addn. of ethylene to a n1-allyl complex, using the dicationic ethylene complex as catalyst