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) 2 HgX 2 ] (where X = N 3 − for 1 and 1 ′ or OCN − for 2 and 2 ′) have been synthesized using [CuL] as ‘‘ligand complex” (where H 2 L = 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.