5-Chloro-N-(4-nitrophenyl) pentanamide is an intermediate in the synthesis of the anticoagulant, Apixaban (Watson et al., Reference Watson, Whiteside and Perry2011; Jiang and Ji, Reference Jiang and Ji2013). Commercial 5-chloro-N-(4-nitrophenyl) pentanamide was purchased from Haoyuan Chemexpress Co., Ltd., (Shanghai, China), recrystallized in methanol and dried. The sample was then ground into powder (HPLC >98%, ρ = 1.391 g cm⁻³) and mounted on a flat zero background plate. X-ray powder diffraction measurement was performed at room temperature using an X'Pert PRO diffractometer (PANalytical Co., Ltd., The Netherlands) with a PIXcel 1D detector and CuKα radiation (generator setting: 40 kV and 40 mA). The diffraction data were collected over the angular range from 4° to 50°2θ with a step size of 0.013 13°2θ and a counting time of 30 ms step⁻¹. The software package Material Studio 8.0 (Accelrys Co., Ltd., CA, USA) was used to process the data in the Analytical & Testing Center (Sichuan University, China). The X-ray powder diffraction pattern was pre-treated by subtracting the background, smoothing, and stripping off the Kα ₂ component. Automatic indexing results were obtained by X-Cell method (Neumann, Reference Neumann2003). The preliminary cell from indexing was refined using the Pawley method (Pawley, Reference Pawley1981). The refinement confirmed that the sample crystallizes in the monoclinic space group P2₁/c (14), with a = 8.036(4) Å, b = 15.972(5) Å, c = 9.829(5) Å, α = 90°, β = 104.227(2)°, γ = 90°, V = 1222.98 Å³, Z = 4, and ρ _x = 1.3941 g cm⁻³. Figure 1 shows the Powder X-ray diffraction pattern of the compound. The values of 2θ _obs, d _obs, I _obs, h, k, l, 2θ _cal, d _cal, and ∆2θ are listed in Table SI.

Figure 1. Powder X-ray diffraction pattern of 5-Chloro-N-(4-nitrophenyl) pentanamide