Résumé
We analyse and discuss the evolution of primordial molecules during the beginning stage of the early cloud formation using an updated primordial lithium chemistry. As Puy & Signore (1996)[A&A, 305, 371], (1997)[NewA, 2, 299], we consider a simple model of a collapsing protocloud after the recombination epoch but paying special attention to the LiH formation by radiative association from excited Li atoms. Because the rate of LiH destruction through collisions with H atoms is only estimated we find that, at present,
the percentage of primordial lithium converted to LiH is quite uncertain.