Big macrocyclic assemblies of carboranes (big MACs): synthesis and crystal structure of a macrocyclic assembly of four carboranes containing alternate ortho- and meta-carborane icosahedra linked by para-phenylene units.

Fox, M.A.; Howard, J.A.K.; MacBride, J.A.H.; Mackinnon, A.; Wade, K.

Abstract

The macrocyclic compound, [1,2-C2B10H10-1,4-C6H4-1,7-C2B10H10-1,4-C6H4](2) (5)-a novel cyclooctaphane, was prepared by condensation of the C,C'-dicopper(l) derivative of meta-carborane with 1,2-bis(4-iodophenyl)-ortho-carborane. The X-ray crystal structure of 5.C6H6-6C(6)H(12) was determined at 150 K, revealing an extremely loose packing mode. Molecule 5 has a crystallographic C-s and local C-2r symmetry; the macrocycle adopts a butterfly (dihedral angle 143degrees) conformation with the ortho-carborane units at the wingtips and the phenylene ring planes roughly perpendicular to the wing planes. Multinuclear NMR spectra suggest that molecule 5 in solution inverts rapidly via the planar D-2h geometry, which (from ab initio HF/6-31G* calculations) is only I kcal mol(-1) higher in energy than the C-2r. one. An attempt to prepare an even larger macrocycle, comprising three para-carborane and three ortho-carborane units linked by six para-phenylene units, was unsuccessful.

Citation

Fox, M., Howard, J., MacBride, J., Mackinnon, A., & Wade, K. (2003). Big macrocyclic assemblies of carboranes (big MACs): synthesis and crystal structure of a macrocyclic assembly of four carboranes containing alternate ortho- and meta-carborane icosahedra linked by para-phenylene units. Journal of Organometallic Chemistry, 680(1-2), 155-164. https://doi.org/10.1016/s0022-328x%2803%2900313-9

• Journal Article Type: Article
• Publication Date: 2003-08
• Journal: Journal of Organometallic Chemistry
• Print ISSN: 0022-328X
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 680
• Issue: 1-2
• Pages: 155-164
• DOI: https://doi.org/10.1016/s0022-328x%2803%2900313-9
• Public URL: https://durham-repository.worktribe.com/output/1602482