A structural distribution is an intrinsic nature of TiCl4-capped MgCl2 nanoplates, and its comprehension would uncover the origin of distributions in the primary structure of polyolefins produced by Ziegler- Natta catalysts. Such fundamental understanding is one of the prerequisites of the systematic design of catalysts. Here, we performed a series of machine learning-aided structure determination for TiCl4-capped MgCl2 nanoplates of different sizes and chemical compositions. Structural and electronic distributions of TiCl4 were analyzed on the basis of 10(6) structures, which were obtained in the course of the structure determination. Such a systematic investigation revealed that i) TiCl4 tends to adsorb on {110} surfaces as mononuclear species, while adsorption on {100} is not negligible, and that ii) even within the same mononuclear species on {110} surfaces, the steric environment and charge state of TiCl4 are distributed. A preliminary examination on ethylene insertion suggested that the TiCl4 distribution would generate the polymer primary structure distribution obtained by Ziegler-Natta catalysts. (c) 2020 Elsevier Inc. All rights reserved.