Abstract
| - The synthesis of cyclic tetraselenadiynes could be achieved by a stepwise approach. Key steps werethe reaction of the lithium salt of trimethylsilylacetylene (1) with α,ω-diselenocyanatoalkanes 2(m)(m = 2−5). By treating the bis-lithium salt of the resulting α,ω-diselenaalkadiynes 4(m) (m = 2−5)again with 2(n) (n = 2−5) the cyclic tetraselenadiynes 5(m.n) resulted, with methylene chains oflength m and n between the SeC⋮CSe units. The structures of seven ring systems could beinvestigated in the solid state. These investigations reveal that the molecular structures aredetermined by the rigid SeC⋮CSe units, which try to adopt torsion angles of the CH2−Se σ-bondsbetween 60° and 90°. In the solid state, the systems 5(3.3) and 5(5.5) show columnar structuresthat can be traced back to close contacts between Se atoms of neighboring rings.
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