of import vs central

of import is not a noun while central is a noun.

Word	Noun	Adjective	Verb	Adverb
of import	No	Yes	No	No
central	Yes	Yes	No	No

of import (noun)	central (noun)
	a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication

of import (adjective)	central (adjective)
of great significance or value	in or near a center or constituting a center; the inner area
	serving as an essential component