Trinuclear complexes of [CuL] (H₂L = N,N′-bis(salicylidene)-1,4-butanediamine) with HgX₂ (X⁻ = N₃⁻ and NCO⁻): facile crystallization with Z′ = 1 and Z′ = 0.5 for both complexes

Abstract

Two trinuclear centrosymmetric hetero-metallic copper(II)–mercury(II) complexes of general formula [(CuL)₂HgX₂] (where X = N₃⁻ for 1 and 1′ or OCN⁻ for 2 and 2′) have been synthesized using [CuL] as ‘‘ligand complex” (where H₂L = N,N′-bis(salicylidene)-1,4-butanediamine) and structurally characterized. Rapid crystallization of both the complexes yielded isomorphous crystals with two independent half molecules (Z′ = 1) in 1 and 2 but the crystals that were grown slowly from the same solutions are not isomorphous and contain single half molecule (1′ and 2′) in the asymmetric units (Z′ = 0.5). Crystal structure analyses reveal that the complexes have discrete trinuclear entity in which two square planar [CuL] units are bonded to a mercury ion through double phenoxido bridges. The Hg(II) is in a six-coordinate distorted octahedral environment being bonded additionally to two mutually trans nitrogen atoms of terminal azide (for 1 and 1′) and cyanate (for 2 and 2′). Higher Z′ compounds are stabilized probably due to weak interactions (C–H⋯N/O and C/H⋯π interactions) that help to hold two independent molecules together.