Application of the Suzuki reaction to the asymmetric desymmetrisation of 1,2- and 1,3-disubstituted bulky cobalt metallocenes

Reaction of (η⁵-cyclopentadienyl)(η⁴-tetraphenylcyclobutadiene)cobalt with Hg(OAc)₂ (2.3 equiv) in 1:1 MeOH/CH₂Cl₂ followed by the addition of LiCl resulted in the formation of (η⁵-1,2-dichloromercuricyclopentadienyl)(η⁴-tetraphenylcyclobutadiene)cobalt (33%) and its 1,3-isomer (6%). Following conversion into their corresponding diiodides these compounds were desymmetrised by Suzuki reactions with ArB(OH)₂ employing [(R)-BINAP]PdCl₂, with the highest ee of 24% being obtained for (η⁵-1-iodo-3-(2-methoxyphenyl)cyclopentadienyl)(η⁴-tetraphenylcyclobutadiene)cobalt.     

Inhibierung der Autoxydation von Polypropylenoxid durch KOH

Ohne Zusammenfassung     

The dynamic stereochemistry of the allylic ligand in a μ-allylic complex of platinum(II)

¹H NMR studies of an equilibrium mixture of 1,1,1,5,5,5-hexafluoropentane-2,4-dionato-π-allylplatinum(II) [IA] and bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)bis(μ-allyl)diplatinum(II) [IB] show that the μ-allylic ligands of (IB) exhibit temperature dependent tautomeric behaviour, giving rise to a site-exchange between protons on these ligands.     

Quaternary adamantine selenides and tellurides of the form I III IV VI4

The preparation of a range of polycrystalline Selenides and Tellurides of the form I III IV VI₄ was undertaken. Twelve Selenides with quaternary composition were prepared but the eight Tellurides attempted did not grow as quaternaries. Single crystal samples of CuGaSnSe₄ were grown by vapour transport. X-Ray powder photography confirmed that the quaternary Selenides have tetragonal Chalcopyrite structure with a c/a ratio of approximately 2. A systematic variation of unit cell volume and of c/a was found over the entire range of compounds grown.     

Vibronic properties of the F+ centre in strontium oxide

The shape and moments of the F⁺ absorption band in SrO have been measured between 4.2K and 300K. Analysis of the moments gives the effective frequency of the vibrational modes interacting with the centre as $\text{h}\text{?}\text{ω = 236 ± 20 cm}{}^{-1}$, and the Huang-Rhys factors for cubic and non-cubic modes as S_C = 3 ± 1 and S_NC = 4 ± 1 respectively.