Playing with different metalloligands [NiL] and Hg to [NiL] ratios to tune the nuclearity of Ni(II)–Hg(II) complexes: Formation of di-, tri-, hexa- and nona-nuclear Ni–Hg clusters

Five new hetero-metallic nickel(II)–mercury(II) complexes, [(NiL1)HgCl2] (1), [(NiL1)2HgCl2] (3), [(NiL1)2Hg(N3)2] (4), [{(NiL2)2Hg(N3)(μ1,1-N3)}2] (5) and [{(NiL2)2Hg(N3)(μ1,1-N3)HgCl2}2{Hg(N3)(μ1,1-N3)}] (6) have been synthesized by reacting metalloligands [NiL1] or [NiL2] (where H2L1 is N,N′-bis(salicylidene)-1,2-ethylenediamine and H2L2 is N,N′-bis(salicylidene)-1,3-propanediamine) with HgX2 (X− = Cl− or N3−) at different molar ratios. All five complexes have been characterised by X-ray single-crystal structural, elemental and spectroscopic analyses. In complex 1, the Hg(II) ion is coordinated to two phenoxido oxygen atoms of one [NiL1] moiety and two terminal chloride ions to form a NiHg dinuclear complex. In the trinuclear complexes 3 and 4, the central Hg(II) ion is coordinated by two terminal [NiL1] units through two phenoxido oxygens from each and two terminal chloride (in 3) or azide (in 4) ions. The centrosymmetric hexanuclear complex 5 consists of two trinuclear [(NiL2)2Hg(N3)(μ1,1-N3)] units, where the phenoxido bridges connect two terminal Ni(II) atoms of the trinuclear units. In these trinuclear units, one azido ligand adopts a μl,1-briding mode between Hg and Ni whereas the other one is terminal. In the nonanuclear complex 6, two tetranuclear [{(NiL2)2Hg(N3)(μ1,1-N3)}HgCl2] units are linked to a central Hg(II) positioned on a two fold axis, via chlorido, azido, and phenoxido bridges. The tetranuclear unit is formed by the addition of a HgCl2 molecule to a trinuclear [(NiL2)2 Hg(N3)(μ1,1-N3)] unit, similar to that present in 5. Complex 5 shows weak ferromagnetic interactions (J = +2.1 cm−1) between the two octahedral Ni(II) ions through double phenoxido bridges with a Ni–O–Ni bond angle of 95.87(11)°.

Five new Ni(II)–Hg(II) hetero-metallic complexes of various nuclearities with salen type Schiff bases have been synthesized by changing metalloligands, the reactant ratios and the counter anions.Figure optionsDownload as PowerPoint slide