Schiff-bases are well-know chelating ligands in coordination chemistry. 1 During the last decade, Schiff-base complexes have been applied to catalytic reactions and biological systems. 2 Schiff bases can be used to obtain optical materials and conducting polymers. 3,4 Thus, new optical and organic conducting materials can be produced by using these compounds. These compounds, containing Schiff bases, seem to be suitable candidates for further chemical modifications, and may be used to produce optical communication and optical devices. 5 Recently, three Schiff-base compounds were reported with nitrobenzaldehyde, and have been structurally characterized. 6-8 In this research N,N′-bis(3-nitrobenzylidene)butane-1,4diamine was prepared by the reaction of butane-1,4-diamine (0.3 mmol, 27 mg) and 3-nitrobenzaldehyde (0.6 mmol, 91 mg), which were dissolved in chloroform (10 ml). The mixture was stirred at room temperature for 5 h (Fig. 1). Single crystals suitable for X-ray structure analysis could be obtained by crystallization from an ethanol and dichloromethane (1:1) solution, which afforded yellow crystals. The crystal and structure-refinement data are summarized in Tables 1-3. H atoms were placed at calculated positions, with C-H distances of 0.95-0.99 Å, and treated as riding atoms, with Uiso(H) = 1.3Ueq(C). In Fig. 1, two 3-nitrobenzaldehyde groups are bridged by butane-1,4-diamine via two C=N double bonds in a roughly linear geometry. This molecule is on the x61

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.

The title compound, C20H18F6N2, a Schiff base, was synthesized by the reaction of 1,4‐diaminobutane and 4‐(trifluoromethyl)benzaldehyde in chloroform solution and was crystallized from a mixture of ethanol and dichloromethane (1:1). It lies across a crystallographic inversion centre. The crystal packing is stabilized by C—H...F hydrogen bonds and π–π interactions.

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