This handbook presents structural data on free polyatomic molecules. Since the structure of molecules defines the chemical, physical and biological properties of matter, this information is crucial for understanding, explaining and predicting chemical reactions and biochemical processes, developing new drugs and materials as well as studying interstellar media. Covering the structural data published between 2009 and 2017, this book supplements the previous Landolt–Börnstein volumes “Structure Data of Free Polyatomic Molecules” (eds. K. Kuchitsu, N. Vogt, M. Tanimoto), which included data from the literature published up to 2008. It systematizes and describes peculiarities of molecular structures for about 1000 compounds studied mainly by gas-phase electron diffraction and rotational spectroscopy. All structures are given in three-dimensional representations.

This volume Structure of Free Polyatomic Molecules Basic Data contains frequently used data from the corresponding larger Landolt-Börnstein handbooks in a low price book for the individual scientists working in the laboratory. Directories link to the more complete volumes in the library. The book contains important information about a large number of semiconductors.

Since the publication of Volumes II/7 in 1976 and its supplements II/15 in 1987 and II/21 in 1992, the information on the structure of free molecules in the ground state and in excited electronic states has increased considerably. Therefore this volume II/23 contains data from 148 inorganic and 498 organic polyatomic free molecules (including free radicals and molecular ions) published between 1990 and 1993 inclusively and a small number of structures published 1994. All experimental methods for the determination of structural data of free molecules have been considered, all data obtained by these methods have been critically evaluated and compiled. The structural data for more than 3400 polyatomic free molecules can be completely surveyed and easily retrieved by means of this volume.

This volume contains data on the geometric parameters (internuclear distances, bond angles, dihedral angles of internal rotation etc.) of free polyatomic molecules including free radicals and molecular ions. This survey on structure data is made of four subvolume, each containing the geometric parameters determined in the gas phase either by an analysis of the rotational constants (and sometimes the vibrational constants) obtained from microwave, infrared, Raman, electronic and photoelectron spectroscopy or by an analysis of electron diffraction intensities. Most of the structures listed in the tables are for molecules in the electronic ground state, but structures for electronically excited states have also been included as far as they are available. In this third subvolume, the structure of molecules containing three for four carbon atoms are listed.