Cyclic Tetraselenadiynes: Rigid Cycles with Long-Range van der Waals Forces between Chalcogen Centers
摘要:
The synthesis of cyclic tetraselenadiynes could be achieved by a stepwise approach. Key steps were the reaction of the lithium salt of trimethylsilylacetylene (1) with alpha,w-diselenocyanatoalkanes 2(m) (m = 2-5). By treating the bis-lithium salt of the resulting alpha,w-diselenaalkadiynes 4(m) (m = 2-5) again with 2(n) (n = 2-5) the cyclic tetraselenadiynes 5(m.n) resulted, with methylene chains of length m and n between the SeCequivalent toCSe units. The structures of seven ring systems could be investigated in the solid state. These investigations reveal that the molecular structures are determined by the rigid SeCequivalent toCSe units, which try to adopt torsion angles of the CH2-Se sigma-bonds between 60degrees and 90degrees. In the solid state, the systems 5(3.3) and 5(5.5) show columnar structures that can be traced back to close contacts between Se atoms of neighboring rings.
Cyclic Tetraselenadiynes: Rigid Cycles with Long-Range van der Waals Forces between Chalcogen Centers
作者:Daniel B. Werz、Rolf Gleiter、Frank Rominger
DOI:10.1021/jo020014i
日期:2002.6.1
The synthesis of cyclic tetraselenadiynes could be achieved by a stepwise approach. Key steps were the reaction of the lithium salt of trimethylsilylacetylene (1) with alpha,w-diselenocyanatoalkanes 2(m) (m = 2-5). By treating the bis-lithium salt of the resulting alpha,w-diselenaalkadiynes 4(m) (m = 2-5) again with 2(n) (n = 2-5) the cyclic tetraselenadiynes 5(m.n) resulted, with methylene chains of length m and n between the SeCequivalent toCSe units. The structures of seven ring systems could be investigated in the solid state. These investigations reveal that the molecular structures are determined by the rigid SeCequivalent toCSe units, which try to adopt torsion angles of the CH2-Se sigma-bonds between 60degrees and 90degrees. In the solid state, the systems 5(3.3) and 5(5.5) show columnar structures that can be traced back to close contacts between Se atoms of neighboring rings.
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.