A Carborane-Based Analogue of Poly(p-phenylene)

Polyhedral monocarbaborane chemistry

“…We now report that, in the presence of iron(III) chloride hexahydrate -{FeCl 3 (OH 2 ) 6 } -anion 1 reacts with two-electron donor species such as dimethylsulfide, aniline and pyridine to form compounds such as [6-Ph-9-(SMe 2 )-arachno-6-CB 9 H 12 ] (2), [6-Ph-9-(NH 2 Ph)-arachno-6-CB 9 H 12 ] (3) and [6-Ph-9-(NC 5 H 5 )-arachno-6-CB 9 H 12 ] (4). Note that, for convenience in this text, we use the formulation {FeCl 3 (OH 2 ) 6 } to describe iron(III) chloride hexahydrate, rather than the more exact, but more cumbersome, solid-state formulation [FeCl 2 (OH 2 ) 4 ]Cl(OH 2 ) 2 ; we acknowledge an (inexact) comment from a referee about this.…”

“…Characterisation of these compounds was further substantiated by 11 B and 1 H NMR spectroscopy. These three arachno compounds 2, 3 and 4 have similar 11 B NMR spectra, with six resonances corresponding to the chemically inequivalent sets of atoms B(1,3), B(2), B(4), B(5,7), B(8,10) and B (9). Full assignments for both 11 B and 1 H NMR spectra are given in Section 4.…”

“…As with all new compounds reported in this paper, this crystallographically determined structure is consistent with the 11 B and 1 H NMR spectra recorded for the bulk sample, confirming that the single crystals selected for the X-ray work were representative. Thus, this closo ten-vertex monocarbadecaborane [1-Ph-6-(NC 5 H 5 )-closo-1-CB 9 H 8 ] (6) shows six resonance centres in its 11 B NMR spectrum, arising from the inequivalent B(2,3), B(4,5), B(6), B (7,9), B(8) and B(10) positions. As expected, the B(6) resonance for the pyridine-substituted position appears as a singlet in the 11 B NMR spectrum, whereas the other signals appear as doublets arising from couplings 1 J( 11 B-1 H).…”

“…The relatively recent discovery of the Brellochs reaction, between nido-B 10 H 14 and aldehydes in alkaline solution, for the generation of {CB 9 } cluster species, now offers a convenient one-step entry into monocarbaborane chemistry, with the choice of aldehyde making a variety of C-substituted monocarbaboranes available [1][2][3][4][5][6]. There is some ongoing interest in the synthesis of species that combine carbaborane units with organyl systems to generate interesting molecular frameworks, for example in the construction of rod-like units, due in part to their potential applicability in areas such as nanoarchitectural construction [7][8][9][10][11][12][13] and effect chemistry such as liquidcrystal behaviour [14,15]. As a contribution to these areas, we report here on a potentially generic route to neutral monocarbaborane derivatives that is afforded by the reaction of the [6-Ph-nido-6-CB 9 H 11 ] À anion 1 with two-electron donor species, which we here exemplify principally by pyridine-type species.…”

“…On prolonged treatment with {FeCl 3 (OH 2 ) 6 } oxidative cluster closure of the four compounds 4, 7, 9 and 11 that have pyridine-type ligands gives the neutral closo ten-vertex monocarbaboranes [1-Ph-6-L-closo-1-CB 9 H 8 ], compounds 6, 8, 10 and 12, respectively, in yields of 49-92%. All new species 2, 3, 4,6,7,8,9,10,11 and 12 are characterised by single-crystal X-ray diffraction analysis and NMR spectroscopy. [This paper is an annotated exposition of parts of an oral presentation at the…”