A novel trinuclear zinc(II) cluster with a tetrahedral ZnO4 core

The reaction of 0.67 molar equivalents of the O,N,O'-tridentate zwitterionic Schiff base (2Z,4E)-4-[(2-hydroxyphenyl)iminio]pent-2-en-2-olate (H2L) with one equivalent of zinc(II) acetate in methanol affords a novel trinuclear Zn(II) cluster, di-mu-acetato-1:2kappa2O:O';2:3kappa2O:O'-dimethanol-1kappaO,3kappaO-bis{mu-2-[(2E,3Z)-4-oxidopent-3-en-2-ylideneamino]phenolato}-1:2kappa4O2,N,O4:O4;2:3kappa4O4:O2,N,O4-trizinc(II), [Zn3(C11H11NO2)2(C2H3O2)2(CH4O)2], (I), in which two bridging acetate ligands link the terminal square-based pyramidal Zn(II) ions to the approximately tetrahedral Zn(II) ion at the core of the cluster. The ZnO(4) coordination group of the central Zn(II) ion is established by two bridging phenolate and two bridging acetate O atoms. The remaining four coordination sites of each terminal Zn(II) ion are occupied by methanol and deprotonated H2L. Furthermore, the Zn-bound methanol hydroxyl groups are involved in complementary hydrogen bonding with the Zn-bound enolate O atom of a neighbouring molecule, about an inversion centre in each case. The structure of (I) is therefore best described as an extended one-dimensional hydrogen-bonded chain of trinuclear Zn(II) clusters.