Synthesis and derivatization of naphthylcalcium halides as well as degradation in THF solution

The direct synthesis of 1-naphthyliodide and -bromide with calcium powder yields (thf)4Ca(Naph)I (1) and [(thf)3Ca(Naph)Br]2 (2), respectively. The metathesis reaction of 1 with KN(SiMe3)2 gives (thf)3Ca(Naph)–N(SiMe3)2 (3). In 2 and 3 very small Ca–C bond lengths of 252.8(4) and 251.4(6) pm, respectively, are observed. These compounds slowly decompose in THF solution via ether cleavage reactions. From this degradation, [(thf)4CaBr2] · naphthalene (4) crystallizes from THF solutions. Furthermore, decomposition of 1 in THF solution yields ethene and naphthalene whereas intermediate ethenolate undergoes subsequent degradation to an acetylide.