A binuclear CuII/CaII thio-cyanate complex with a Schiff base ligand derived from o-vanillin and ammonia

Abstract

The new heterometallic complex, aqua-1κO-bis-(μ₂-2-imino-methyl-6-meth-oxy-phenolato-1κ² O ¹,O ⁶:2κ² O ¹,N)bis-(thio-cyanato-1κN)calcium(II)copper(II), [CaCu(C₈H₈NO₂)₂(NCS)₂(H₂O)], has been synthesized using a one-pot reaction of copper powder, calcium oxide, o-vanillin and ammonium thio-cyanate in methanol under ambient conditions. The Schiff base ligand (C₈H₉NO₂) is generated in situ from the condensation of o-vanillin and ammonia, which is released from the initial NH₄SCN. The title compound consists of a discrete binuclear mol-ecule with a {Cu(μ-O)₂Ca} core, in which the Cu⋯Ca distance is 3.4275 (6) Å. The coordination geometries of the four-coordinate copper atom in the [CuN₂O₂] chromophore and the seven-coordinate calcium atom in the [CaO₅N₂] chromophore can be described as distorted square planar and penta-gonal bipyramidal, respectively. In the crystal, O-H⋯S hydrogen bonds between the coordinating water mol-ecules and thio-cyanate groups form a supra-molecular chain with a zigzag-shaped calcium skeleton.

Keywords: Schiff base ligand; calcium; copper; crystal structure; heterometallic; hydrogen bond.