Unbranched Catacondensed Polygonal Systems Containing Hexagons and Tetragons

An algebraic solution for the isomer numbers of unbranched a-4- catafusenes is presented. An a-4-catafusene is a catacondensed polygonal system consisting of exactly o: tetragons each and otherwise only hexagons. This analysis, which makes use of certain triangular matrices including the Pascal triangle, is a continuation of a previous work on di-4-catafusenes. By serendipity, the problem was reversed in the sence that the systems were considered as possessing \u277 hexagons each and otherwise only tetragons. Under this viewpoint the enumeration problem could be solved more directly and led to explicit formulas. Finally, the resuIts are applied to catafusenes as a special case

Unbranched Catacondensed Polygonal Systems Containing Hexagons and Tetragons

An algebraic solution for the isomer numbers of unbranched a-4- catafusenes is presented. An a-4-catafusene is a catacondensed polygonal system consisting of exactly o: tetragons each and otherwise only hexagons. This analysis, which makes use of certain triangular matrices including the Pascal triangle, is a continuation of a previous work on di-4-catafusenes. By serendipity, the problem was reversed in the sence that the systems were considered as possessing \u277 hexagons each and otherwise only tetragons. Under this viewpoint the enumeration problem could be solved more directly and led to explicit formulas. Finally, the resuIts are applied to catafusenes as a special case

Enumeration of Polyhex Hydrocarbons to h: 17

This paper describes a rather efficient algorithm that enumerates nonisomorphic geometrically planar, simply connected polyhexes (hexagonal systems). It has been implemented in Modula-2 and used to determine andclassifythepertinentsystemswithli <lThexagons. Theresultforh:17,vi2., 1151594643, isnew

Molecular vibrations of complex with trigonal ligands

A normal coordinate analysis was performed for the compound [Pt(NH3)4]2+ which has a square planar framework structure (PtN4 with local symmetry D4h) and tetrahedral NH3 groups (local symmetry C3v). C4h over-all structure was assumed (two opposite animine groups are considered to be in staggered position). Two general valence force fields which reproduce satisfactorily the observed frequencies for the whole complex as well as the H/D isotopic derivative have been developped. These calculations for the whole complex (C4h) are compared with the point mass model approximation (PtN'4, D4h with mN', = mNH3 ), the validity of which is confirmed. Finally the refined force field for [Pt(NH3)4]2+ was used to calculate the frequencies of various isotopes (14N/15N, H/D) and the mean amplitudes at absolute zero and 298 °K of the mother molecule