Hunting for the magnesium(I) species: formation, structure, and reactivity of some donor-free Grignard compounds.

Magnesium bromide radicals have to be prepared as high-temperature molecules and trapped as a metastable solution because a seemingly simple reduction of donor-free Grignard compounds failed. However, the essential role of magnesium(I) species during the formation of Grignard compounds could be demonstrated experimentally.

Organosilicon-mediated total synthesis of the triquinane sesquiterpenes (±)-β-isocomene and (±)-isocomene.

We describe an efficient total synthesis of the sesquiterpenes (±)-β-isocomene and (±)-isocomene using a Lewis acid-promoted [3 + 2] cycloaddition of allyl-tert-butyldiphenylsilane as the key-step.

First enantioselective total synthesis of neocarazostatin B, determination of its absolute configuration and transformation into carquinostatin A.

The first enantioselective total synthesis of neocarazostatin B, the determination of its absolute configuration and transformation into carquinostatin A are described.

A new synthetic entry to phosphinophosphinidene complexes. Synthesis and structural characterisation of the first side-on bonded and the first terminally bonded phosphinophosphinidene zirconium complexes [mu-(1,2:2-eta-tBu2P=P)[Zr(Cl)Cp2]2] and [[Zr(PPhMe2)Cp2](eta1)-P-PtBu2)].

The reactions of lithiated diphosphanes with transition metal chlorides constitute a new general entry to phosphinophosphinidene complexes: the reaction of Cp2ZrCl2(Cp = C5H5) with tBu2P-P(SiMe3)Li (molar ratio approximately 1:1) yields [mu-(1,2:2-eta-tBu2P=P)[Zr(Cl)Cp2]2]; the reaction of Cp2ZrCl2 with tBu2P-P(SiMe3)Li (molar ratio approximately 1:2) and an excess of PPhMe2 in DME yields the first terminally bonded phosphinophosphinidene complex, [[Zr(PPhMe2)Cp2](eta1-P-PtBu2)].

Demetalation of Tricarbonyl(cyclopentadienone)iron Complexes Initiated by a Ligand Exchange Reaction with NaOH-X-Ray Analysis of a Complex with Nearly Square-Planar Coordinated Sodium.

A sequential exchange of one carbonyl ligand by a hydrido ligand with NaOH, and then by an iodo ligand with iodopentane and finally treatment with acid transforms tricarbonyl(η-cyclopentadienone)iron complexes into dicarbonyl(η-hydroxycyclopentadienyl)iodoiron complexes. These iodo complexes demetalate with high selectivity to the corresponding free ligands on contact with air in daylight. Under basic reaction conditions at the stage of the iodo complex an anionic dicarbonyl(η-cyclopentadienone)iodoiron complex is generated, which is dimeric in the solid state and has an almost square-planar arrangement of the ligands at the sodium counterion.

Cp Al I : An Intermediate in Reactions Leading to Elemental Aluminum and Al Species?

A first indication of the reaction mechanism for the disproportionation of an Al species to an Al compound and metallic aluminum is provided by the isolation of [Cp Al I ], an intermediate that is formed in the ready disproportionation of [Cp*Al] in the presence of Al I (see reaction sequence). This potentially key role of Al compounds could be of great significance for large-scale industrial processes. X=I, Cl.