Unique formation of mono-, tetra- and nona-nuclear zinc complexes from protonolysis reactions of [Zn(dmpzm)Et2]

Abstract

Protonolysis reactions of [Zn(dmpzm)Et₂] (1) with acetic or formic acid in different molar ratios gave rise to four mononuclear zinc complexes [ZnEt(dmpzm)(L)] (2: L = OAc; 3: L = HCOO) and [Zn(dmpzm)(L)₂] (4: L = OAc; 5: L = HCOO), one nonanuclear zinc complex [Zn(μ₄-O)₂(ZnEt)₆(μ₃-OAc)₄(μ′₃-OAc)₂{Zn(dmpzm)Et}₂] (6), and one tetranuclear zinc complex [Zn₄(μ₄-O)(dmpzm)₃Et₃] (7). Compounds 1–7 were characterized by elemental analysis, IR spectra, ¹H NMR spectra, and the crystal structures of 1, 3, 4, 6, and 7 were determined by single-crystal X-ray crystallography. In the structures of 1, 3, and 4, the central Zn atom is tetrahedrally coordinated by two N atoms of one dmpzm and two C atoms of two Et groups (1), or one C atom of one Et group and one O atom of formate ligand (3), or two O atoms of two acetates (4). In the structure of 6, a heptanuclear [Zn(μ₄-O)₂(ZnEt)₆(μ₃-OAc)₄] core is connected with two [Zn(dmpzm)Et]⁺ fragments via a pair of μ′₃-OAc ligands. Compound 7 consists of a Zn₄(μ₄-O) tetrahedron in which three Zn atoms are further saturated by two N atoms from dmpzm ligands and an ethyl group while one Zn center is coordinated by three C atoms from the methylene group of the three dmpzm ligands.