Trends in ortho-carboranes 1-X-2-R-1,2-C2B10H10 (R = Ph, Me) bearing an exo-CN-bonded substituent group (X = NO, N=NR ' or NHR '')

Fox, M.A.; Peace, R.J.; Clegg, W.; Elsegood, M.R.J.; Wade, K.

Abstract

The preparation and crystal structures of four ortho-carboranyl-nitrogen compounds, PhCboNdouble bond; length as m-dashN(C6H4Me-4) (1), PhCboNHNH(C6H4Me-4) (2), MeCboNHNHPh (3) and PhCboNHOH (4) (Cbo = 1,2-C2B10H10; nitrogen groups at cage carbon C1, Ph or Me at C2), the last as a 1,4-dioxane solvate, are reported. Comparisons of their structures with those of other ortho-carboranyl-nitrogen systems studied earlier reveal further correlations between their cage C–C and exo-C–N bond distances and bond orders. Substituent orientations and bond distances (cage C1–C2, exo-C1–N) in RCboNHR′′ systems (R = Ph or Me at C2) are consistent with dative π-bonding from a nitrogen lone pair into the cage carbon p-AO otherwise responsible for cage C1–C2 σ bonding. Their C1–C2 bond distances are remarkably sensitive to the planar (sp2) or pyramidal (sp3) nature of the NHR′′ group. The Ndouble bond; length as m-dashO and Ndouble bond; length as m-dashNR′ residues in RCboX prefer to be orientated in plane with the cage C1–C2 in contrast to the RCboNHR′′ systems. Correlations between their cage C–C and exo-C–N bond distances and the 11B NMR chemical shifts of their antipodal boron atoms reflect the π-bonding characteristics of the nitrogen substituent.

Citation

Fox, M., Peace, R., Clegg, W., Elsegood, M., & Wade, K. (2009). Trends in ortho-carboranes 1-X-2-R-1,2-C2B10H10 (R = Ph, Me) bearing an exo-CN-bonded substituent group (X = NO, N=NR ' or NHR ''). Polyhedron, 28(12), 2359-2370. https://doi.org/10.1016/j.poly.2009.04.041

• Journal Article Type: Article
• Publication Date: Aug 1, 2009
• Deposit Date: Dec 14, 2011
• Publicly Available Date: Jul 3, 2014
• Journal: Polyhedron
• Print ISSN: 0277-5387
• Electronic ISSN: 1873-3719
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 28
• Issue: 12
• Pages: 2359-2370
• DOI: https://doi.org/10.1016/j.poly.2009.04.041
• Keywords: Carborane, Amine, Nitroso, Benzene, Cluster, π-Bonding.
• Public URL: https://durham-repository.worktribe.com/output/1524175