From the self-assembly of the typical Salen-type Schiff-base ligand

H

2

L

and Zn(OAc)

2

·

2

H

2

O in the molar ratio of 1:1 or 1:2

the mononuclear [Zn(L)(H

2

O)] (

1

) or binuclear [Zn

2

(L)(OAc)

2

(H

2

O)] (

2

) are obtained

respectively. For both complexes

1

and

2

the unsaturated five-coordinate coordination environment to the catalytic active centers (Zn

2+

ions) permits the monomer insertion for the effective solution copolymerization of cyclohexene oxide and maleic anhydride. All the solution copolymerizations afford poly(ester-

co

-ether)s

while lower catalyst and co-catalyst concentrations are helpful for the formation of alternating polyester. Of the three co-catalysts

4-(dimethylamino)pyridine is found to be the most efficient

while an excess thereof is detrimental for chain growth of the copolymers.