The structural influence of ligand coordination and hydrogen bonding capabilities in the crystal engineering of metal thiosemicarbazide compounds with malonate

Abstract

The reaction of sodium malonate with the thiosemicarbazide complexes [M(L)₂](NO₃)₂ [M = Ni, Zn; L = NH₂NHC(S)NH₂ (tsc), NH₂NHC(S)NHEt (Ettsc)] afforded the compounds [Ni(tsc)₂]₂[Ni(κ²-malonate)₂(OH₂)₂][NO₃]₂·4H₂O 1, [Ni(Ettsc)₂][Ni(κ²-malonate)₂(OH₂)₂]·4H₂O 2, [Ni(Ettsc)₃][Hmalonate]NO₃·2H₂O 3, {[Zn(tsc)(μ-κ¹,κ²-malonate)]·H₂O}_n4 and [Zn₂(Ettsc)₃(μ,-κ¹,κ²-malonate)(OH₂)][NO₃]₂5, all of which have been crystallographically characterised. For compounds 1, 2, 4 and 5, coordination of malonate to a metal centre is observed, in conjunction with displacement of one or more thiosemicarbazide ligands. In contrast, a ligand redistribution reaction occurs in 3 leading to a tris(4-ethylthiosemicarbazide)nickel(II) cation, with hydrogen malonate [Hmalonate]⁻ included as an anion. Compounds 1–3 and 5 are ionic, with the ions connected into hydrogen-bonded networks. Compound 4 forms coordination polymers, which are linked into the gross structure via hydrogen bonds. The nature of malonate coordination is dependent on the metal, whilst the hydrogen bonding capabilities of the thiosemicarbazide ligand influence the interactions observed in forming the three-dimensional structures.