Synthesis and structure of mixed metal tetradentate Schiff base complexes containing copper(II) and zinc(II) ions - Stabilisation of a supramolecular structuret

Department of Chemistry, Inorganic Chemistry Section, Jadavpur University, Kolkata-700 032, India

E-mail : rajiblal@hotmail.com

Kristallographisches Institut, Albert-Ludwigs-Universitaet Freiburg, Hebelstrasse 25,

D-791 04 Freiburg, Germany

Manuscript received 10 August 2011, revised 19 March 2012, accepted 11 April 2012

The tetradentate copper(ll) Schiff base complexes, Cu(SALEN) and Cu(5-BrSALEN), underwent facile reactions with zinc perchlorate hexahydrate, Zn(CIO₄)₂.6H₂O resulting excellent complex formations. Solid compounds of formula [{CuL}₂Zn(H₂O)₂](CIO₄)₂.2CuL [where CuL = N,N' -ethylenebis(salicylideneiminato)copper(II), Cu(SALEN); N,N'- ethylenebis(5-bromosalicylideneiminato)copper(ll), Cu(5-BrSALEN)] were isolated as powdery solid materials. The complexes are characterized by magnetic, spectroscopic and electrochemical properties. X-Ray crystallographic structure analysis performed on [{Cu(SALEN)}₂Zn(H₂O)₂](CIO₄)₂.2Cu(SALEN) (I) showed it to crystallize in monoclinic space group, C2/c with Z = 4, and α = 28.3450(10), b = 10.4330(3), c = 23.7993(9) Å, β = 111.073(3)⁰ . The copper(ll) ions are in distorted square planar coordination whereas the central Zn^II ion is bound to two water molecules and to four oxygen atoms of the two Cu(SALEN) Schiff base complex molecules in a distorted octahedral fashion. The structure consists of two perchlorate ions and two further molecules of Cu(SALEN) complexes.