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

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.

Synthesis and crystal structure of the dinuclear copper(II) Schiff base complex μ-hydroxido-μ-chlorido-bis{[bis(trans-2-nitrocinnamaldehyde)ethylenediamine]chloridocopper(II)} dichloromethane sesquisolvate

“…We have continued our exploration of complexes of the ligand N,N 0 -bis(trans-2-nitrocinnamaldehyde)ethylenediamine (Nca 2 en) and report here its first dinuclear complex, namely [Cu 2 Cl 3 (OH)(Nca 2 en) 2 ]Á1.5CH 2 Cl 2 , (I). The 11 previously reported complexes (referenced in Clegg et al, 2015) of cobalt, nickel, copper, zinc and silver are all mononuclear and fourcoordinate, with a single Nca 2 en ligand and either one other bidentate or two monodentate ligands, except for the homo-leptic salt [Cu(Nca 2 en) 2 ]ClO 4 (Dehghanpour et al, 2006). The structure reported here thus introduces new features to the series.…”

“…Transition metal complexes of Schiff base ligands have been of interest for many years, with particular application in catalysis and magnetism, and their structures have been investigated extensively (Archer & Wang, 1990;Chang et al, 1998;Chaturvedi, 1997;Costamagna et al, 1992). Since the 2014 Cambridge Structural Database (CSD) search mentioned in our previous report of one particular Schiff base ligand and one of its complexes (Clegg et al, 2015), the number of entries in the CSD (Version 5.37, including one update, November 2015; Allen, 2002;Groom & Allen, 2014) for purely organic compounds containing the skeleton R-CH N-CH 2 CH 2 -N CH-R, in which R is any alkyl or aryl group, has increased to 165 and the number of metal complexes of such ligands to 1872. The chemistry of copper complexes is of particular interest owing to their importance in biological and industrial processes (Que & Tolman, 2002).…”

Crystal structure of catena-poly[aqua[(μ2-4,5-dicarboxylato-2-(2-carboxylatophenyl)imidazol-1-ido-κ4 N,O,O′:N′)](μ2-4,4′-bipyridine-κ2 N:N′)dicopper(II)], C22H14Cu2N4O7

“…There are two kinds of O-H• • • O hydrogen bonds between coordination water molecules and carboxylate groups. In addition, there are weak π-π stacking interactions between the N1/N2/C2/C3/C5 imidazole ring and the N3/C13/C14/C15/C16/C17 pyridine ring, with a centroidcentroid distance of 3.7485(2) Å, and π-π stacking interactions between the N3/C13/C14/C15/C16/C17 pyridine ring and C6-C11 benzene ring, with a centroid-centroid distance of 3.7838(2) Å, which are in the range for common π-π interactions [18][19][20]. Adjacent chains are linked by the aforementioned hydrogen bonds and π-π interactions, leading to a three-dimensional supramolecular architecture in the solid state.…”

Syntheses, structures and characterization of isomorphous CoII and NiII coordination polymers based on 2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole and benzene-1,4-dicarboxylate

“…In addition, there are strong slipped-parallelstacking interactions between the C10-C15 benzimidazole benzene rings of adjacent layers. In polymer (I), the inter-centroid distance is 3.693 (6) Å , the perpendicular interplanar distance is 3.557 (4) Å and the slippage is 0.994 Å , which are in the range for commoninteractions (Clegg et al, 2015;Wei et al, 2015). Similar to polymer (I), the inter-centroid distance is 3.686 (6) Å , the perpendicular interplanar distance is 3.557 (4) Å and the slippage is 0.967 Å in polymer (II).…”