Oliver Heinemann

A FACILE ACCESS TO CPCR(ACAC)CL AND RELATED SYSTEMS

Abstract CpCr(acac)Cl has been prepared by reacting CpCr(THF)Cl2 with sodium acetylacetonate. Related Cr compounds containing the C5Me5 group and ethylacetoacetate have also been studied. Catalysts active for the polymerization of ethylene are obtained by treating these compounds with aluminium alkyls while the title compound reacts with Et2AlCl or Et3Al to give [CpCr(μ-Cl)Et]2.

Probing Metal Complexation, Structure, Ligand Lability and Dissociative Ligand‐Exchange Mechanism in the Slipped Triple‐Decker Complexes [{(η5‐CpR)Co}2‐μ‐{η4:η4‐arene}] (R=Me5, 1,2,4‐tri‐tert‐butyl; arene=toluene, benzene)

Triple-deckers 1 and 3 are extremely labile with respect to an exchange of their bridging arene middle deck. Crossover exchange experiments between 1, 3, benzene, and azulene have unraveled for the first time a dissociative mechanism for ligand exchange in organometallic triple-decker complexes. Further preparative utility of this high exchange lability can be foreseen and is herein exemplified by the synthesis of a new class of structurally characterized dinuclear Co complexes containing bridging azulenes.

Synthesis and characterization of organometallic precursors for the preparation of Sn/chalcogenide heterostructures

Abstract Synthesis, spectroscopic and structural characterization as well as thermal behavior of a series of molecular organometallic Sn/chalcogenide complexes, which present valuable complexes for the MOCVD process, is reported. These compounds are obtained from a reaction of the stannylene complex [{{(CH3)3Si}2(CH)}2Sn]2]] with elemental O2, S8, Se8 or metallic Te in high yields at RT in an organic solvent. These compounds are crystalline solids which are soluble in common organic solvents and are stable in air over extended periods of time, which make their handling easy.

Synthesis, structure, spectroelectrochemical and theoretical investigations of Formation of a cobalt complexed stannacycle via a mixed alkyne-stannylene cycloaddition reaction

Abstract Reacting 2-butyne with the cobalt stannylene complexes [CpR(C2H4)CoSn{CH{Si(CH3)3}2}2] RH (5), Me5 (6) affords different cyclotrimerization products depending on the Cp ligand used. For the CpR (RH) derivative 5, reaction with 2-butyne is exclusively intermolecular, resulting in the formation of a 5:4:1 mixture of a 20e sandwich complex [(η5−Cp)Co(η6−C6Me6)], free hexamethylbenzene (hmb), and free stannylene [Sn{CH(SiMe3)2}2]. Replacing Cp against Me5Cp affords only trace amounts of the 20e sandwich complex [(η5-Me5Cp)Co(η6-C6Me6)], no free hmb and stannylene. The main product of the reaction is the cobalt-stannacyclopentadiene complex 8 which is formed via cycloaddition of two alkyne molecules and an SnR2 (CH(SiMe3)2) fragment. Crystalline 8 is characterized by single-crystal structure analysis which reveals a cobalt bonded stanna-cyclopentadiene ring ligand with a distorted tetrahedrally coordinated Sn atom and an η4 coordinated cobalt atom. Electrochemistry coupled with electron paramagnetic resonance spectroscopy and extended Huckel calculations shows that the Co(I) complex 8 undergoes reversibly one-electron oxidation to the corresponding Co(II) monocation [8]−, whereas further oxidation to the Co(III) congener [8]2− is followed by chemical complications.