A systematic examination of classical and multi-center bonding in heteroborane clusters

Abstract

This paper presents a systematic study of multicenter and classical bonding on a broad series of experimentally known heteroboranes covering closo, nido, arachno and hypho types of cages with incorporated tetrel, pnictogen or chalcogen heterovertices up to the third-row elements. The nature of bonding is studied using a novel quantum-chemical tool, the intrinsic atomic/bond orbital (IAO/IBO) approach, which provides a direct connection between quantum chemistry and chemical concepts. We also discuss how the computed IBO properties are related to molecular observables such as interatomic distances, molecular electrostatic potential surfaces and dipole moments.

Thiaboranes on Both Sides of the Icosahedral Barrier: Retaining and Breaking the Barrier with Carbon Functionalities

“…The S atom of nido ‐SB 10 H 11 − has formed two classical S−B 2c2e bonds in the open face and one multicenter B−S−B 3c2e bond in the closed face. This bonding pattern is analogues to that previously reported for nido ‐7,8,10‐C 2 SB 8 H 10 . The S atom of 12‐ and 13‐vertex nido thiaboranes only has formed classical 2c2e S−B bonds.…”

“…It should be noted that the electron transmission agrees with the generally accepted electronegativity concept in this case. It thus reflects the fact that exo‐skeletal bonds are of the classical 2‐center 2‐electron nature . Consequently, the methylated borons in the 11 B NMR spectrum of 7,8,9,10,11,12‐Me 6 ‐ closo ‐1‐SB 11 H 5 are significantly paramagnetically deshielded to high frequencies (i. e. downfield‐shifted) with respect to the parent compound (−5.6 ppm for B(7–11), 18.2 ppm for B(12)).…”

“…It thus reflects the fact that exo-skeletal bonds are of the classical 2-center 2-electron nature. [29] Consequently, the methylated borons in the 11 B NMR spectrum of 7,8,9,10,11,12-Me 6 -closo-1-SB 11 H 5 are significantly paramagnetically deshielded to high frequencies (i. e. downfield-shifted) with respect to the parent compound (À 5.6 ppm for B(7-11), 18.2 ppm for B (12)). This quantitatively agrees with the trend observed for methylated carbaboranes.…”

Quantitative Assessment of B−B−B, B−Hb−B, and B−Ht Bonds: From BH3 to B12H122−

“…This will be studied in more detail in future work. Our analysis revealed the existence of a recently proposed B−B−B−B 4‐center‐2‐electron bond, which will also be the subject of a future investigation.…”

“…This will be studied in more detail in future work. Our analysis revealed the existence of a recently proposed BÀ BÀ BÀ B 4-center-2electron bond, [159] which will also be the subject of a future investigation. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57…”