Yes, COMPLEXES is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, M 3, P 3, L 1, E 1, X 8, E 1, S 1.

Is it a valid word?

COMPLEXES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a conceptual whole made up of complicated and related parts
a compound described in terms of the central atom to which other atoms are bound or coordinated
(psychoanalysis) a combination of emotions and impulses that have been rejected from awareness but still influence a person's behavior
a whole structure (as a building) made up of interconnected or related structures

Also: coordination compound, building complex.