Find the word definition

Wiktionary
manganocene

n. (context chemistry English) The metallocene containing a manganese atom

Wikipedia
Manganocene

Manganocene or bis(cyclopentadienyl)manganese(II) is an organomanganese compound with the formula [Mn(CH)]. It is a thermochromic solid that degrades rapidly in air. Although the compound is of little utility, it is often discussed as an example of a metallocene with ionic character.