Borane Polyhedra as Building Blocks for Unknown but Potentially Isolatable New Molecules – Extensions based on Computations of the Known B18H22 Isomers

Abstract

Abstract. Known borane polyhedral cluster characteristics can be used for predicting new architectural constructs. We propose additional structures derived from B 18 H 22 : three positional isomers different from the well-known anti-B 18 H 22 and syn-B 18 H 22 boranes. We have also derived two new cyclic structures based on the condensation of borane pentagonal pyramids and bipyramids. The concatenation of polyhedral borane molecules is also considered from a mathematical point of view.

Nomenclature for boranes and related species (IUPAC Recommendations 2019)

“…Here the trivial descriptors syn and anti refer to the mutual disposition of the two nido-decaborane open faces, either on the same flank (syn) or on opposite flanks (anti) of the molecule. These mutual dispositions have been further categorised as 'transoid', implying that the open faces are trans to each other, engendering trivial transoid-anti and transoid-syn descriptors for these two known isomers [18]. The alternative 'cisoid' conjunctions, with the open faces cis to each other, have not yet been realised experimentally.…”

“…This cage therefore needs to be named by the located hydrogen method (see Section BN-4.1) as 7,7,9-tris(triphenylphosphane-P)-9-dehydro-7:8,9:10-di-μH-isonido-7-iridadecaborane(11) (36). Using the 'debor' method [2p, 36] the isonido structure, 7,7,9-(PPh 3 ) 3 -isonido-7-IrB 9 H 10 (36) could equally be named as 1,1,8-tris(triphenylphosphane-P)-8-dehydro-2-debor-1,5:4,8-di-μH-[C 2v -(12422)-Δ 18 -closo]-1-iridaundecaborane (11), based on the closo structure as numbered in Fig. 1, or 35A.…”

Pentagonal chains and annuli as models for designing nanostructures from cages

“…Boron and hydrogen atoms are represented by bigger and smaller spheres, respectively. See [5] for a more comprehensive explanation of these structures.…”

“…One of the perspective trends for creating new molecules of nanotechnological interest deals with constructs which may be formed by chemically linking of cage molecules [3][4][5]. Among such constructs, chains and rings from pentagonal pyramidal clusters are rather simple instances, which have simplified "unfolded" representations by regular pentagons in E 2 [5].…”

“…The enumeration of chemical graphs (molecular graphs) and geometric molecular models satisfying given constraints [1][2][3][4][5] is one of the fundamental problems in chemoinformatics, because it leads to a variety of useful applications including structure determination and development of novel chemical compounds. One of the perspective trends for creating new molecules of nanotechnological interest deals with constructs which may be formed by chemically linking of cage molecules [3][4][5].…”