Iron-aromatics coordination in molecular clouds

Abstract

Aromatic molecules (generally supposed to be PAHs, i.e. polycyclic aromatic hydrocarbons) are assumed to be present in the interstellar medium (ISM). Serra et al. (1992) proposed that efficient organometallic reactions should occur in the ISM between the PAHs and the iron atoms or ions, leading to the formation of organometallic complexes, the organometallic bonding being of the same order of stability as an aromatic C-H bond. We present in this paper a model taking into account the formation and the photodissociation reactions inside typical cloud configurations. The results show that organometallic complexes are stable inside interstellar clumps protected by an extinction A v c.a. 4-5 mag against the local star light or the interstellar radiation field (ISRF)