Bridges and Vertices in Heteroboranes

• Published in: Molecules (Basel, Switzerland) Vol. 28; no. 1; p. 190
• Main Authors: Macgregor, Stuart A, Welch, Alan J
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 26-12-2022; MDPI
• Subjects: Apexes; Borane; boron cluster; bridge; crystal structure; heteroborane; Molecular structure; Physiological aspects; Polyhedra; structure; vertex; United Kingdom; DFT calculation; vertex; crystal structure; boron cluster; bridge; heteroborane; structure
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules28010190

A number of (hetero)boranes are known in which a main group atom
'bridges' a B-B connectivity in the open face, and in such species
has previously been described as simply a bridge or, alternatively, as a vertex in a larger cluster. In this study we describe an approach to distinguish between these options based on identifying the best fit of the experimental {B
} cluster fragment with alternate exemplar {B
} fragments derived from DFT-optimized [B
H
]
models. In most of the examples studied atom
is found to be better regarded as a vertex, having 'a 'verticity' of ca. 60-65%. Consideration of our results leads to the suggestion that the radial electron contribution from
to the overall skeletal electron count is more significant than the tangential contribution.