Long-Chain Molecular Crystals Antimony(III) Alkanethiolates\nSb(SC<sub><i>n</i></sub>H<sub>2<i>n</i>+1</sub>)<sub>3</sub> (<i>n</i> ≥ 12): Synthesis, Crystal\nand Electronic Stru

Currently, there is not much success\nin solving the molecular and\ncrystal structures of long-chain metal alkanethiolate complexes [M(SC<sub><i>n</i></sub>H<sub>2<i>n</i>+1</sub>)<sub><i>m</i></sub>] at the atomic level. Taking Sb(SC<sub>16</sub>H<sub>33</sub>)<sub>3</sub> (<b>1</b>) as an example, we herein disclose\nthe structural characteristics of long-chain trivalent antimony(III)\nalkanethiolates Sb(SC<sub><i>n</i></sub>H<sub>2<i>n</i>+1</sub>)<sub>3</sub> (<i>n</i> ≥ 12) by single-crystal\nX-ray crystallography. Specifically, the Sb atom is three-coordinated\nby alkanethiolate ligands and a slightly distorted triangular pyramid\nSbS<sub>3</sub> core is formed owing to the unique intramolecular\nstereochemistry of three alkyl chains, namely, two of them almost\nparallel aligning and the third chain extending alone around the SbS<sub>3</sub> core. We further determine the conformation, spatial orientation\nand packing density of alkyl chains in <b>1</b> along with a\ncomparison to those in other long-chain crystalline systems, and reveal\nthe roles of intermolecular van der Waals and Sb···S\nsecondary interactions in molecular self-assembly, which enables <b>1</b> to be a layer-structured molecular crystal with a monoclinic <i>P</i>2<sub>1</sub>/<i>c</i> unit cell. The band structures\nand the atomic orbital contributions to the valence band maximum and\nconduction band minimum for <b>1</b> have also been evaluated\nby DFT calculations and rationally correlated with its optical absorption\nproperty. This study will help understand and discover new structures\nand structure−property relations of long-chain chemical systems.