Structural diversity in copper(I) iodide complexes with 6-thioxopiperidin-2-one, piperidine-2,6-di-thione and isoindoline-1,3-di-thione ligands

Abstract

Copper(I) iodide complexes are well known for displaying a diverse array of structural features even when only small changes in ligand design are made. This structural diversity is well displayed by five copper(I) iodide compounds reported here with closely related piperidine-2,6-di-thione (SNS), isoindoline-1,3-di-thione (SNS6), and 6-thioxopiperidin-2-one (SNO) ligands: di-μ-iodido-bis-[(aceto-nitrile-κN)(6-sulfanylidenepiperidin-2-one-κS)copper(I)], [Cu₂I₂(CH₃CN)₂(C₅H₇NOS)₂] (I), bis-(aceto-nitrile-κN)tetra-μ₃-iodido-bis-(6-sulfanylidenepiperidin-2-one-κS)-tetra-hedro-tetra-copper(I), [Cu₄I₄(CH₃CN)₄(C₅H₇NOS)₄] (II), catena-poly[[(μ-6-sulfanylidenepiperidin-2-one-κ² O:S)copper(I)]-μ₃-iodido], [CuI(C₅H₇NOS)] _n (III), poly[[(piperidine-2,6-di-thione-κS)copper(I)]-μ₃-iodido], [CuI(C₅H₇NS₂)] _n (IV), and poly[[(μ-isoindoline-1,3-di-thione-κ² S:S)copper(I)]-μ₃-iodido], [CuI(C₈H₅NS₂)] _n (V). Compounds I and II crystallize as discrete dimeric and tetra-meric complexes, whereas III, IV, and V crystallize as polymeric two-dimensional sheets. To the best of our knowledge, compound III is the first instance of an extended hexa-gonal [Cu₃I₃] structure that is not supported by bridging ligands. Structures I, II, and IV display weak to moderately strong Cu⋯Cu cuprophilic inter-actions [Cu⋯Cu inter-nuclear distances range between 2.5803 (10) and 2.8485 (14) Å]. All structures except III display weak hydrogen-bonding inter-actions between the N-H of the ligand and the μ₂ and μ₃-I^- atoms. Structure III contains classical N-H⋯O inter-actions between the SNO ligands that connect the mol-ecules in a three-dimensional framework. Complex V features π-π stacking inter-actions between the aryl rings of the SNS6 ligands within the same polymeric sheet. In structure IV, there were three partially occupied solvent mol-ecules of di-chloro-methane and one partially occupied mol-ecule of aceto-nitrile present in the asymmetric unit. The SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] was used to correct the diffraction data for diffuse scattering effects and to identify the solvent mol-ecules. The given chemical formula and other crystal data do not take into account the solvent mol-ecules.

Keywords: coordination complexes; copper(I) iodide; crystal structure.