Bond indices, enthalpies and relative stabilities of real and hypothetical closo-BnHc−n clusters (n = 5–12; c = 0, 2 or 4) as revealed by the molecular-orbital bond index method

Robert Mulvey, M E ONEILL, K WADE, R SNAITH

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Abstract

Bond indices (I) have been calculated, using the CNDO-based molecular-orbital bond index method, for real and hypothetical closo borane species, BnHc−n (n = 5–12; c = 0, 2 or 4), and used to infer their relative stabilities by means of the bond index (I)bond enthalpy [E (kJ mol−1)] equations E(BB) = 297.9I(BB) and E(BH) = 374.8I(BH). For the species able to tolerate n + 2 skeletal electron pairs (n = 8, 9 or 11) in closed-shell electronic configurations, estimates of the relative stabilities of alternative nido structures for the anions BnH4−n have been made. Detailed assessments of the changes in bond index with electron numbers of particular edge types for BnHc−n species (n = 8, 9 or 11; c = 0, 2 or 4) have been carried out, providing quantitative confirmation of earlier qualitative predictions, and showing that generally for the “normal” closo BnH2−n species addition or removal of an electron pair leads to the same type of polyhedral distortion, because, where the HOMO of BnH2−n is bonding for a particular edge, the LUMO is antibonding.
LanguageEnglish
Pages1437-1447
Number of pages11
JournalPolyhedron
Volume5
Issue number9
DOIs
Publication statusPublished - 1986

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Molecular orbitals
Enthalpy
molecular orbitals
enthalpy
Electrons
Boranes
electrons
boranes
Anions
Negative ions
anions
estimates
configurations
predictions
electronics

Keywords

  • bond indices
  • enthalpies
  • molecular-orbital bond index method

Cite this

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title = "Bond indices, enthalpies and relative stabilities of real and hypothetical closo-BnHc−n clusters (n = 5–12; c = 0, 2 or 4) as revealed by the molecular-orbital bond index method",
abstract = "Bond indices (I) have been calculated, using the CNDO-based molecular-orbital bond index method, for real and hypothetical closo borane species, BnHc−n (n = 5–12; c = 0, 2 or 4), and used to infer their relative stabilities by means of the bond index (I)bond enthalpy [E (kJ mol−1)] equations E(BB) = 297.9I(BB) and E(BH) = 374.8I(BH). For the species able to tolerate n + 2 skeletal electron pairs (n = 8, 9 or 11) in closed-shell electronic configurations, estimates of the relative stabilities of alternative nido structures for the anions BnH4−n have been made. Detailed assessments of the changes in bond index with electron numbers of particular edge types for BnHc−n species (n = 8, 9 or 11; c = 0, 2 or 4) have been carried out, providing quantitative confirmation of earlier qualitative predictions, and showing that generally for the “normal” closo BnH2−n species addition or removal of an electron pair leads to the same type of polyhedral distortion, because, where the HOMO of BnH2−n is bonding for a particular edge, the LUMO is antibonding.",
keywords = "bond indices, enthalpies , molecular-orbital bond index method",
author = "Robert Mulvey and ONEILL, {M E} and K WADE and R SNAITH",
year = "1986",
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pages = "1437--1447",
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TY - JOUR

T1 - Bond indices, enthalpies and relative stabilities of real and hypothetical closo-BnHc−n clusters (n = 5–12; c = 0, 2 or 4) as revealed by the molecular-orbital bond index method

AU - Mulvey, Robert

AU - ONEILL, M E

AU - WADE, K

AU - SNAITH, R

PY - 1986

Y1 - 1986

N2 - Bond indices (I) have been calculated, using the CNDO-based molecular-orbital bond index method, for real and hypothetical closo borane species, BnHc−n (n = 5–12; c = 0, 2 or 4), and used to infer their relative stabilities by means of the bond index (I)bond enthalpy [E (kJ mol−1)] equations E(BB) = 297.9I(BB) and E(BH) = 374.8I(BH). For the species able to tolerate n + 2 skeletal electron pairs (n = 8, 9 or 11) in closed-shell electronic configurations, estimates of the relative stabilities of alternative nido structures for the anions BnH4−n have been made. Detailed assessments of the changes in bond index with electron numbers of particular edge types for BnHc−n species (n = 8, 9 or 11; c = 0, 2 or 4) have been carried out, providing quantitative confirmation of earlier qualitative predictions, and showing that generally for the “normal” closo BnH2−n species addition or removal of an electron pair leads to the same type of polyhedral distortion, because, where the HOMO of BnH2−n is bonding for a particular edge, the LUMO is antibonding.

AB - Bond indices (I) have been calculated, using the CNDO-based molecular-orbital bond index method, for real and hypothetical closo borane species, BnHc−n (n = 5–12; c = 0, 2 or 4), and used to infer their relative stabilities by means of the bond index (I)bond enthalpy [E (kJ mol−1)] equations E(BB) = 297.9I(BB) and E(BH) = 374.8I(BH). For the species able to tolerate n + 2 skeletal electron pairs (n = 8, 9 or 11) in closed-shell electronic configurations, estimates of the relative stabilities of alternative nido structures for the anions BnH4−n have been made. Detailed assessments of the changes in bond index with electron numbers of particular edge types for BnHc−n species (n = 8, 9 or 11; c = 0, 2 or 4) have been carried out, providing quantitative confirmation of earlier qualitative predictions, and showing that generally for the “normal” closo BnH2−n species addition or removal of an electron pair leads to the same type of polyhedral distortion, because, where the HOMO of BnH2−n is bonding for a particular edge, the LUMO is antibonding.

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KW - molecular-orbital bond index method

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DO - 10.1016/S0277-5387(00)83505-6

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