INTERACTIONS IN CRYSTALS .99. AKALI-METAL CONTACT-ION MULTIPLES OF ACENAPHTHYLENE AND FLUORANTHENE DIANIONS - FIVE-MEMBERED AND SIX-MEMBERED RING COORDINATION [German]

摘要

Stimulated by qualitative MO considerations, the non-alternant pi-hydrocarbons acenaphthylene and fluoranthene have been reduced in their ether solutions under aprotic conditions by alkali metals to their dianions. These crystallize as contact ion multiples of different structures: the (15-crown-5)-solvated sodium salt of acenaphthylene is a monomeric contact ion triple [(H2CH2CO)(5)Na+C12H8++Na+(OCH2CH2)5](1) with the ten-fold coordinated Na+ counter cations above and below the cyclopentadienyl ring. In contrast, the DME- or diglyme-solvated Na+- and Li+-salts of fluoranthene dianion [(R(2)O)(2)Me(+)C(16)H(10)(++)Me(+)(OR(2))(2)]infinity crystallize in polymer strings containing eight-fold coordinated Li+ or ten-fold coordinated Na+ counter cations above and below different of the two naphthalene six-membered rings. For these rather unexpected coordination differences, MNDO calculations based on the structural data provide a plausible rationale: the negative charge in the acenaphthylene dianion is predominantly located within the five-membered ring and in the fluoranthene dianion within the naphthalene six-membered rings. [References: 32]