An unexpected polyhydroxyl-bridged tetranuclear Zn II complex and a benzoquinone compound derived from metal-ion promoted reactivity of Schiff base ligands were synthesized and characterized. The reaction of zinc(II) acetate dihydrate with oxime-type Schiff base ligand HL 1 [HL 1 = 1-(3-((3,5-dibromosalicylaldehyde)amino)phenyl) ethan-1-one O-benzyl oxime] in methanol, acetone, and acetonitrile resulted in the chemoselective cleavage of the C=N bond of the Schiff base HL 1 , and then the further addition of acetone to two salicylaldehyde molecules derived from cleavage of the C=N bond in situ α,α double aldol reaction promoted by Zn II ions. The newly formed ligands H 4 L 2 coordinate to four Zn II ions forming a defect-dicubane core struc-

Oxime-type compounds are a traditional class of chelating ligands widely used in coordination and analytical chemistry [1][2][3] . They can accommodate one or more metal centers to form complexes with interesting properties and applications 4-6 . In the last few years, a large number of oxime-type compounds and their complexes are reported 7,8 . In present report, the synthesis and crystal structure of 1-(4-{[(E)-3,5-dibromo-2hydroxybenzylidene]amino}-phenyl)ethanone O-benzyloxime are reported. EXPERIMENTAL 4-Aminoacetophenone, O-benzylhydroxylamine, 3,5dibromosalicylaldehyde were purchased and used without further purification. The other reagents and solvents were analytical grade reagents from Tianjin Chemical Reagent Factory. C, H and N analyses were carried out with a GmbH VariuoEL V3.00 automatic elemental analyzer. X-Ray single crystal structure was determined on a Bruker Smart 1000 CCD area detector. Melting points were measured by the use of a microscopic melting point apparatus made in Beijing Taike Instrument Limited Company and the thermometer was uncorrected.General procedure: 1-(4-{[(E)-3,5-Dibromo-2-hydroxybenzylidene]amino}phenyl)-ethanone O-benzyloxime was synthesized by O-benzylhydroxylamine, 4-aminoacetophenone and 3,5-dibromosalicylaldehyde 9 . To an ethanolic solution (6 mL) of O-benzylhydroxylamine (340.9 mg, 3 mmol) was added an ethanol solution (12 mL) of 4-aminoaceto-

Particular attention has recently been paid to the synthesis and crystal structure of salamo-type compounds and their analogues 1,2 . These compounds can easily form polynuclear complexes in which the metal centers are bridged through organic ligands, because of their enormous variety of structural topologies as well as their unique properties in host-guest chemistry, magnetism, asymmetric catalysis, electronic conductivity 3-6 . This subject is currently being pursued in our research, including the applications and study of salamo-type compounds and their metal complexes.In this article, we report the synthesis and crystal structure of a dinuclear Cu(II) complex [Cu2(L 2 )2] with the new ligand 4-methoxysalicylaldehyde-O-(2-hydroxyethyl) oxime (H2L 2 ) which is formed in the course of complexation of an asymmetrical salamo-type compound 5-methoxy-6'-hydroxy-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H3L 1 ) and Cu(II) acetate monohydrate. The obtained results show cleavage of one of the N-O bonds in H3L 1 in the complexation of the ligand H3L 1 with Cu(OAc)2•H2O and give an unexpected dialkoxo-bridged dinuclear Cu(II) complex possessing a Cu-O-Cu-O four-membered ring core instead of the usually desired salamo-type Cu-N2O2 complex. EXPERIMENTAL 2-Hydroxy-4-methoxybenzaldehyde (≥ 99 %) was purchased from Energy Chemical and used without further purification. The others are the same as literature early 1i .

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