Synthesis, characterization and crystal structures of the bidentate Schiff base N,N'-bis(2-nitrocinnamaldehyde)ethylenediamine and its complex with CuNCS and triphenylphosphane

William Clegg; Ross W Harrington; Kazem Barati; Mohammad Hossein Habibi; Morteza Montazerozohori; Arash Lalegani

doi:10.1107/S2053229615010815

Synthesis, characterization and crystal structures of the bidentate Schiff base N,N'-bis(2-nitrocinnamaldehyde)ethylenediamine and its complex with CuNCS and triphenylphosphane

Acta Crystallogr C Struct Chem. 2015 Jul;71(Pt 7):578-83. doi: 10.1107/S2053229615010815. Epub 2015 Jun 18.

Authors

William Clegg¹, Ross W Harrington¹, Kazem Barati², Mohammad Hossein Habibi³, Morteza Montazerozohori⁴, Arash Lalegani³

Affiliations

¹ School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, England.
² Young Researchers Club, Yasouj Branch, Islamic Azad University, Yasouj 75914-353, Iran.
³ Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.
⁴ Chemistry Department, Yasouj University, Yasouj 75914-353, Iran.

PMID: 26146396
DOI: 10.1107/S2053229615010815

Abstract

Reaction of copper(I) thiocyanate and triphenylphosphane with the bidentate Schiff base N,N'-bis(trans-2-nitrocinnamaldehyde)ethylenediamine {Nca2en, (1); systematic name (1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]}, C20H18N4O4, in a 1:1:1 molar ratio in acetonitrile resulted in the formation of the complex {(1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]-κ(2)N,N'}(thiocyanato-κN)(triphenylphosphane-κP)copper(I)], [Cu(NCS)(C20H18N4O4)(C18H15P)] or [Cu(NCS)(Nca2en)(PPh3)], (2). The Schiff base and copper(I) complex have been characterized by elemental analyses, IR, electronic and (1)H NMR spectroscopy, and X-ray crystallography [from synchrotron data for (1)]. The molecule of (1) lies on a crystallographic inversion centre, with a trans conformation for the ethylenediamine unit, and displays significant twists from coplanarity of its nitro group, aromatic ring, conjugated chain and especially ethylenediamine segments. It acts as a bidentate ligand coordinating via the imine N atoms to the Cu(I) atom in complex (2), in which the ethylenediamine unit necessarily adopts a somewhat flattened gauche conformation, resulting in a rather bowed shape overall for the ligand. The NCS(-) ligand is coordinated through its N atom. The geometry around the Cu(I) atom is distorted tetrahedral, with a small N-Cu-N bite angle of 81.56 (12)° and an enlarged opposite angle of 117.29 (9)° for SCN-Cu-P. Comparisons are made with the analogous Schiff base having no nitro substituents and with metal complexes of both ligands.

Keywords: Schiff base; copper(I) complex; crystal structure; synchrotron study; tetrahedral coordination; thiocyanate.