Preparation and characterization of the (3)-1,2- and (3)-1,7-dicarbadodecahydroundecaborate(-1) ions

Steric Effects in Heteroboranes. III. 1-Ph-2-Me-1,2-closo-C2B10H10

“…As far as we are aware, this is the first reported synthesis of the target material by this route and it represents a considerable improvement in terms of overall yield and ease of procedure and work-up over the previous synthesis (Hawthorne, Young, Garrett, Owen, Schwerin, Tebbe & Wegner, 1968). In a typical preparation, B10H14 (0.500g, 4.09mmol), N,N-dimethylaniline (0.496 g, 4.09 mmol) and Me~CPh (0.475 g, 4.09 mmol) were dissolved in toluene (50 ml) and the resulting solution refluxed for 3 h. Evaporation of the mixture in vacuo yielded a yellow oily solid.…”

Substituent Effects on the Fluorescence Properties of ortho‐Carbor­anes: Unusual Emission Behaviour in C‐(2′‐Pyridyl)‐ortho‐carboranes

“…Syntheses: Compounds 1-3 were purchased commercially (KatChem) and purified by repeated sublimations, whereas 4, [68] 5, [69] 6, [68] 7, [69] 8, [70] 9, [71] 10, [71] 11, [72] 12, [73] 13, [74] 14, [74] 15, [72] 16 [75] and 17 [74] were prepared according to literature procedures. 13 Photophysical Measurements: Absorption spectra were measured from 200 to 600 nm (Δλ = 0.5 nm) with a Shimadzu absorption spectrometer.…”

Remarkable cage deboronation and rearrangement of a closo-1,12-dicarbadodecaborane to form a neutral nido-7,9-dicarbaundecaborane

“…9 Such applications depend strongly upon the chemical stability and structural fidelity of the carborane cluster, which in turn depend upon conditions such as temperature and pH. It is well known that closo-1,2-and 1,7-carboranes undergo a selective deboronation 30 reaction under basic conditions with bases like alkoxides, 10,11 fluorides 12 and amines 10,13 to yield the corresponding, anionic nido-7,8-and 7,9-[C 2 B 9 H 12 ] -isomers. In contrast, closo-1,12-carborane is robust to deboronation processes with many bases except hydroxides under extremely harsh conditions.…”

“…A solution of 6·2I in methanol was heated under reflux for three days and the insoluble yellow material that formed was collected by filtration. Analysis of this crude material by NMR spectroscopy and ESI-MS indicated a mixture of a carborane 7, the phosphonium salt [PPh 2 Me 2 ]X 8·X (X = I 17 or OH) and boric 10 acid residues. The 11 B{ 1 H} NMR spectrum of the carborane 7 revealed a 2:3:2:1:1 peak intensity pattern and the 31 P{ 1 H} NMR spectrum contained a single peak at 27.6 ppm.…”

“…The isomer 7,9-(PPh 2 Me) 2 -7,9-C 2 B 9 H 9 7 is calculated to be 31.8 kcal mol -1 more stable than the 2,9-5 (PPh 2 Me) 2 -2,9-C 2 B 9 H 9 isomer A. The cage rearrangement from A to 7 involves two intermediates, 1,7-(PPh 2 Me) 2 -1,7-C 2 B 9 H 9 B and 2,8-(PPh 2 Me) 2 -2,8-C 2 B 9 H 9 C, with the highest computed energy TS barrier at 47.0 kcal mol -1 corresponding to the transition state geometry from A via a cage carbon vertex flip 10 ( Figure 2). The route by cage rearrangement from the paracarborane 6 to meta-carborane 10 followed by deboronation with methanol is ruled out here as this would give the methoxy derivative 12 instead of 7.…”