Structural Properties of Bis(hexacarbonyldicobalt) Complexes with Heteroatoms Next to the Former Triple Bonds − A Contribution to the Mechanism of the Pauson−Khand Reaction
作者:Daniel B. Werz、J. Hilko Schulte、Bernhard J. Rausch、Rolf Gleiter、Frank Rominger
DOI:10.1002/ejic.200300862
日期:2004.6
The bis(hexacarbonyldicobalt) complexes of cyclic diynes with sila-, thia- and selena-substituted acetylene units have been isolated. The structural features of these complexes have been elucidated by means of X-ray diffraction analyses on single crystals. In three cases (24′, 25′ and 29′) the X-ray investigations show bis(pentacarbonyldicobalt) complexes instead of bis(hexacarbonyldicobalt) ones.
Donor-substituted CpCo-stabilized cyclobutadienes and superphanes
作者:Daniel B. Werz、J. Hilko Schulte、Rolf Gleiter、Frank Rominger
DOI:10.1016/j.jorganchem.2004.06.048
日期:2004.9
RCpCoL2 complexes (L-2 = (CO)(2) or COD, R = H, CO2Me, TMS) were reacted with various alkynes substituted with chalcogen atoms adjacent to the triple bonds. These reactions yielded hetero-substituted CpCo-capped cyclobutadienes and superphanes dependent on the ring size of the corresponding cyclic diene used as starting material. Reactions in decaline afforded not only CpCo-capped cyclobutadieno superphanes, but also mixed cyclobutadieno cyclopentadienono superphanes. X-ray analyses do not indicate a significant amount of conjugation between the pi systems and the lone pairs of the heteroatoms whereas cyclic voltammetry reveals an easier oxidation when increasing the number of electron-donating heteroatoms. (C) 2004 Elsevier B.V. All rights reserved.
Tethered Dithiacyclopropenones. Syntheses and Structural Properties of Tetrathiacyclopropenonophanes
作者:Daniel B. Werz、Frank Rominger、Isabella Hyla-Kryspin、Rolf Gleiter
DOI:10.1021/jo001721j
日期:2001.5.1
The reaction of the cyclic tetrathiadiynes 4(m.n) (where m and n indicate the number of methylene groups between the dithiaacetylene units) with sodium trichloroacetate and subsequent hydrolysis of the gem-dichlorocyclopropenes afforded the mono- and biscyclopropenone derivatives 5(m.n) and 6(m.n) in moderate yields. Investigation of the X-ray crystal structures revealed small torsion angles between the CH2-S bond and the C-C double bond, indicating conjugation between the sulfur 3p lone pair and the cyclopropenone ring. The maintenance of the conjugation determines the secondary structure of both (5, 6) ring systems.
Syntheses and Structural Properties of Cyclic Tetrathiadiynes
The four-component cyclization of dilithium acetylide with dithiocyanatoalkanes yielded the hitherto unknown tetrathiacyclodiynes 34, 38, 41, and 43 in moderate yields. The use of the trimethylsilyl protecting group allowed a more efficient and flexible stepwise approach with good yields. The resulting tetrathiacyclodiynes 25−44 were investigated by X-ray analysis. For ring systems with a twist-chair