Chemistry doesn't have a strong preprint tradition like physics, but there's a growing number of platforms for the free deposit and open dissemination of manuscripts prior to peer review, acceptance and publication in journals.(1)
Preprints are most readily found in Google Scholar, but are not widely indexed in more traditional bibliographic databases.
(NOTE: "Preprint" in this context refers to a paper submitted to a journal but not yet peer-reviewed, accepted or published. For meeting preprints (extended abstracts published in advance of a conference presentation) see the page on Conferences & Symposia.)
When citing a preprint, make sure to indicate clearly that it is a preprint (implying not peer-reviewed). If possible, update the preprint reference with a reference (and link) to the published article after it appears.
1. Coudert, F. The rise of preprints in chemistry. Nature Chemistry (2020). https://doi.org/10.1038/s41557-020-0477-5
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