multivalent vs multivalency

multivalent is not a noun while multivalency is a noun.

Word	Noun	Adjective	Verb	Adverb
multivalent	No	Yes	No	No
multivalency	Yes	No	No	No

multivalent (noun)	multivalency (noun)
	(chemistry) the state of having a valence greater than two

multivalent (adjective)	multivalency (adjective)
used of the association of three or more homologous chromosomes during the first division of meiosis
having more than one valence, or having a valence of 3 or higher
having many values, meanings, or appeals