This feature contains Marvin Extensions that offers a set of new KNIME nodes with which users can easily build their own workflows and data mining applications for working with chemical data.
Extension 
ChemAxon/Infocom Marvin Extensions Feature
Included nodes & related workflows
Legal
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Update site information
KNIME Partner Extensions, Version 4.3.0
http://update.knime.com/partner/4.3
In case you can’t install the extension via drag & drop, please check that the update site is activated.