In the set mass of the ZOE impression paste, zinc eugenolate forms:

The chelate (zinc eugenolate) forms a matrix surrounding a core of zinc oxide particles. The chelate is thought to form as an amorphous gel that tends to crystallize giving strength to the set mass. Formation of crystalline zinc eugenolate is greatly enhanced by zinc acetate dehydrate (accelerator) which is more soluble than Zn(OH)2 and can supply zinc ions more rapidly. Ref: BASIC DENTAL MATERIALS by JOHN J MANAPPALLIL ed 4 Pg 252