Syntheses, crystal structures and Hirshfeld surface analysis of 4-(4-nitro-phen-yl)piperazin-1-ium tri-fluoro-acetate and 4-(4-nitro-phen-yl)piperazin-1-ium tri-chloro-acetate.

The synthesis and crystal structures of the mol-ecular salts of 4-(4-nitro-phen-yl)piperazine with tri-fluoro-acetate, namely, 4-(4-nitro-phen-yl)piperazin-1-ium tri-fluoro-acetate, C10H14N3O2 +·C2F3O2 - (I), and with tri-chloro-acetate, namely, 4-(4-nitro-phen-yl)piperazin-1-ium tri-chloro-acetate, C10H14N3O2 +·C2Cl3O2 -, (II), are reported and compared. A partial positional disorder of the anions was found. In both structures, the piperazine rings adopt a chair conformation, whereas the positions of the nitro-phenyl group on the piperazine ring differ from bis-ectional in (I) to equatorial in (II). In both structures, the supra-molecular assemblies are mono-periodic on the basis of the chain-of-rings motifs supported by aromatic π-π inter-actions. Hirshfeld surface analysis was used to explore the inter-molecular close contacts in both crystals. The most dominant contacts of the Hirshfeld surface of the cation-anion pairs of the asymmetric units are O⋯H/H⋯O, and those with a contribution of halogen atoms: F⋯H/H⋯F in (I) and Cl⋯H/H⋯Cl in (II), respectively.

Synthesis and crystal structure of 2-chloro-1-(3-hy-droxy-phen-yl)ethanone.

The structure of 2-chloro-1-(3-hy-droxy-phen-yl)ethanone, C8H7ClO2, an α-halo-ketone is described. The mol-ecule is planar (r.m.s. deviation = 0.0164 Å) and in the crystal, inversion-symmetric dimers are formed as a result of pairs of strong O-H⋯O and weak C-H⋯O hydrogen bonds. A brief comparison is made with structurally related compounds deposited in the CSD. In addition, the synthesis and some spectroscopic details are presented.

Synthesis and crystal structures of 1-benzoyl-4-(4-nitro-phen-yl)piperazine and 1-(4-bromo-benzo-yl)-4-phenyl-piperazine at 90†K.

Synthesis and crystal structures of 1-benzoyl-4-(4-nitro-phen-yl)piperazine, C17H17N3O3, (I) and 1-(4-bromo-benzo-yl)-4-phenyl-piperazine, C17H17BrN2O, (II) are described. Compounds I and II crystallize in the ortho-rhom-bic and monoclinic crystal systems with space groups Pna21 (Z' = 2, I) and P21 (Z' = 1, II), respectively. The crystal of II was a two-component aggregate, treated as a 'twin' for data-acquisition purposes. There are no conventional hydrogen bonds in either I or II, but there are weaker C-H⋯O contacts. Each mol-ecule consists of a central piperazine ring in a chair conformation, with either benzoyl and nitro-phenyl (I) or 4-bromo-benzoyl and phenyl (II) groups attached to different nitro-gen atoms of the piperazine. The various atom-atom contact coverages as qu-anti-fied by Hirshfeld surface analysis fingerprint plots are given.

Syntheses and crystal structures of 4-(4-meth-oxy-phen-yl)piperazin-1-ium 4-methyl-benzoate monohydrate and bis-[4-(4-meth-oxy-phen-yl)piperazin-1-ium] benzene-1,2-di-carboxyl-ate.

Co-crystallization of N-(4-meth-oxy-phen-yl)piperazine with 4-methyl-benzoic acid and with benzene-1,2-di-carb-oxy-lic acid yields the salts 4-(4-meth-oxy-phen-yl)piperazin-1-ium 4-methyl-benzoate monohydrate, C11H17N2O+·C8H7O2 -·H2O (I), and bis-[4-(4-meth-oxy-phen-yl)piperazin-1-ium] benzene-1,2-di-carboxyl-ate, 2C11H17N2O+·C8H4O4 2- (II). These salts both crystallize with Z' = 2, in space groups P and Pna21, respectively. In compound (I), a combination of four O-H⋯O, four N-H⋯O, one C-H⋯O and one C-H⋯π(arene) hydrogen bonds link the six independent components into complex sheets, within which the two piperazine rings, the two anions, and the two water mol-ecules are related by an approximate, non-crystallographic translation along the b-axis direction. In compound (II), sheets containing R 4 4(18) and R 10 12(38) rings are formed by the combined action of eight independent N-H⋯O hydrogen bonds. Comparisons are made with the structures of some related compounds.

Syntheses and crystal structures of 4-(4-nitro-phen-yl)piperazin-1-ium benzoate monohydrate and 4-(4-nitro-phen-yl)piperazin-1-ium 2-carb-oxy-4,6-di-nitro-phenolate.

Crystal structures are reported for two mol-ecular salts containing the 4-(4-nitro-phen-yl)piperazin-1-ium cation. Co-crystallization from methanol/ethyl acetate solution of N-(4-nitro-phen-yl)piperazine with benzoic acid gives the benzoate salt, which crystallizes as a monohydrate, C10H14N3O2·C7H5O2·H2O, (I), and similar co-crystallization with 3,5-di-nitro-salicylic acid yields the 2-carb-oxy-4,6-di-nitro-phenolate salt, C10H14N3O2·C7H3N2O7, (II). In the structure of (I), a combination of O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds links the components into sheets, while in the structure of (II), the supra-molecular assembly, generated by hydrogen bonds of the same types as in (I), is three dimensional. Comparisons are made with the structures of some related compounds.