X‐ray and neutron diffraction studies of 2‐amino‐5‐chloropyridine, C5H5ClN2, were previously carried out at room temperature [Kvick & Backéus (1974). Acta Cryst. B30, 474–480; Kvick, Thomas & Koetzle (1976). Acta Cryst. B32, 224–231]. This report is a redetermination of the crystal structure at 100 K. As previously observed, molecules form centrosymmetric dimers via two N—H...N hydrogen bonds. In addition, C—H...π interactions are generated from molecules related by c‐glide transformations, which form extended two‐dimensional aggregation in the bc plane.

Twelve new compounds of acephate (Ace) analogues were synthesized and characterized by (31)P, (13)C, and (1)H NMR and IR spectroscopy. The probable insecticide potential of these compounds as well as 23 previously prepared molecules with a general skeleton of RC(O)-NH-P(O)X1X2 was predicted by PASS software. Docking analysis showed that hydrophobic interaction and hydrogen bonding were created between the functional groups of Ace derivatives and the receptor sites of acetylcholinesterase. PCA-QSAR indicated that the electronic descriptors are dominated in comparison with the structural descriptors. The experimental-QSAR (R(2) = 0.903 and VIF < 2.997) and DFT-QSAR (R(2) = 0.990 and VIF ≤ 10) models clarified that the net charge of functional groups contributes an important function in an inhibition mechanism. Validity and integrity of this model were confirmed by the LOO cross-validation method with q(2) = 0.940 and low residuals between the training and testing sets. The correlation matrix of DFT-QSAR model confirmed the molecular docking results.

Mixed diamidophosphoric acid esters [(CH 3 ) 2 N][p-H 3 C-C 6 H 4 -O]P(O)X, where X = NH(CH 3 ) (1), NHCH(CH 3 ) 2 (2), NHC(CH 3 ) 3 (3) and p-H 3 C-C 6 H 4 -NH (4) were synthesized and characterized by 31 P, 31 P{ 1 H}, 13 C, 1 H NMR, and IR spectroscopy and mass spectrometry, and single crystal X-ray diffraction analysis for the compounds 3 and 4.

Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.003 Å; R factor = 0.034; wR factor = 0.084; data-to-parameter ratio = 20.1.The P-N bond in the title compound, C 10 H 13 N 2 O 2 P, is shorter [at 1.6104 (15) Å ] than a normal P-N single bond. The N atom deviates slightly from the plane of the three atoms to which it is bonded. The sum of the angles surrounding this N atom is 358 . In the crystal structure, weak C-HÁ Á ÁO hydrogen bonds link molecules into one-dimensional chains along the a-axis direction. ExperimentalCrystal data C 10 H 13 N 2 O 2 P M r = 224.19 Triclinic, P1 a = 6.0322 (9) Å b = 6.8532 (10) Å c = 7.3820 (11) Å = 105.604 (3) = 95.800 (3) = 106.802 (3) V = 276.03 (7) Å 3 Z = 1Mo K radiation = 0.23 mm À1 T = 100 (2) K 0.60 Â 0.12 Â 0.10 mm Data collectionBruker APEXII diffractometer Absorption correction: none 3289 measured reflections 2791 independent reflections 2688 reflections with I > 2(I) R int = 0.020

The anti-AChE activity of phosphoramidates has been noticed for many years. Because of the wide application of phosphoramidates in recent years, there has been a continuing research for synthesis, purification and identification of effective and safe derivatives. In this study some rodenticides with the general formula Me 2 NP(O)( p-OC 6 H 4 -X) 2 , where X ¼ H, CH 3 , Cl, have been synthesized in water (without organic solvent) and characterized by 31 P, 31 P { 1 H}, 13 C and 1 H NMR spectroscopy. Since lipophilicity has been recognized for its importance in QSAR studies, efforts have been made to determine the logP values. The ability of these rodenticides to inhibit human acetylcholinesterase (hAChE) has been predicted with PASS (Prediction of Activity Spectra for Substances) software (version 1.917) and then has been evaluated by a modified Ellman's assay and spectrophotometric measurements.