The identification of main-group molecules having atoms with closed valence p shells, i.e., having atoms with eight valence electrons, is continued into the realm of four-atom molecules. All possible covalently-bonded species, obtained from two independent computer programs, are shown. The method for generalizing to molecules in which some or all atoms have closed valence s shells, i.e., having atoms with two valence electrons, is recalled. A list of all prototype linear/bent four-atom molecules, with dative bonds in addition to covalent and/or van der Waals bonds, is presented (permutations having been culled out). A program code, lists of molecules based on other graphs, and lists of five- and covalently-bonded six-atom species, are available on the Web. For molecules derived from the two other four-vertex graphs, their vast numbers require extensive indexing schemes for the results to be useful. The paper concludes with some preliminary observations concerning the stabilities of four-atom molecules having atoms with closed shells.
Walters, Chris J.; Caviness, Kenneth E.; and Hefferlin, Ray A., "Global Molecular Identification from Graphs. IV. Molecules with Four Closed p-Shell Atoms and beyond" (2003). Faculty Works. 2.