Symmetric and asymmetric 13-vertex bimetallacarboranes by polyhedral expansion

Abstract

Symmetric 4,5,2,3-M(2)C(2)B(9) 13-vertex bimetallacarboranes of cobalt and ruthenium with 14 skeletal electron pairs are afforded by reduction and metallation of 3,1,2-MC(2)B(9) icosahedra; the symmetric species can be converted to their asymmetric 4,5,1,6-M(2)C(2)B(9) isomers by heat, but an easier route is by thermolysis of the reduced species before metallation.

14‐Vertex Heteroboranes with 14 Skeletal Electron Pairs: An Experimental and Computational Study

“…[14] We have shown that the HOMO of the parent borate [B 13 H 13 ] 2À is strongly bonding with respect to the 1-2 and 1-3 edges, and moderately strongly bonding with respect to the 6-9 and 7-8 edges. [15] This allows us to rationalize the facts that the 1-2 and 1-3 distances in 2 are about 0.09-0.10 longer, and the 6-9 and 7-8 distances in 2 are about 0.02-0.04 longer, than the equivalent distances in crystallographically characterized 13-v 14-SEP 4,5,1,6-M 2 C 2 B 9 species (see the Supporting Information). [15,16] The fastest moving band (identified as purple compound 3), the third fastest band (dark green compound 4), and the sixth fastest moving band (purple compound 5) were also studied, with elemental analysis and/or mass spectrometry suggesting the formula [(Cp*Ru) 2 C 2 B 10 H 12 ] for all three.…”

“…[15] This allows us to rationalize the facts that the 1-2 and 1-3 distances in 2 are about 0.09-0.10 longer, and the 6-9 and 7-8 distances in 2 are about 0.02-0.04 longer, than the equivalent distances in crystallographically characterized 13-v 14-SEP 4,5,1,6-M 2 C 2 B 9 species (see the Supporting Information). [15,16] The fastest moving band (identified as purple compound 3), the third fastest band (dark green compound 4), and the sixth fastest moving band (purple compound 5) were also studied, with elemental analysis and/or mass spectrometry suggesting the formula [(Cp*Ru) 2 C 2 B 10 H 12 ] for all three. The 1 H NMR spectra of 3-5 contain one relatively high frequency C cage H resonance signal (d = 8.6 to 10.5 ppm) and two resonance signals corresponding to the Cp* H atoms.…”

“…[14] We have shown that the HOMO of the parent borate [B 13 H 13 ] 2À is strongly bonding with respect to the 1-2 and 1-3 edges,a nd moderately strongly bonding with respect to the 6-9 and 7-8 edges. [15] This allows us to rationalize the facts that the 1-2 and 1-3 distances in 2 are about 0.09-0.10 l onger, and the 6-9 and 7-8 distances in 2 are about 0.02-0.04 longer, than the equivalent distances in crystallographically characterized 13-v 14-SEP 4,5,1,6-M 2 C 2 B 9 species (see the Supporting Information). [15,16] Thef astest moving band (identified as purple compound 3), the third fastest band (dark green compound 4), and the sixth fastest moving band (purple compound 5)w ere also studied, with elemental analysis and/or mass spectrometry suggesting the formula [(Cp*Ru) 2 C 2 B 10 H 12 ]for all three.T he 1 HNMR spectra of 3-5 contain one relatively high frequency C cage H resonance signal (d = 8.6 to 10.5 ppm) and two resonance signals corresponding to the Cp* Ha toms.T he asymmetry of all three compounds is confirmed by their 11 BNMR spectra which exhibit ten equal-integral resonance signals for 4 and 5 and nine resonance signals for 3 (one less signal as aresult of the overlapping of two signals).…”

14‐Vertex Heteroboranes with 14 Skeletal Electron Pairs: An Experimental and Computational Study

“…[14] We have shown that the HOMO of the parent borate [B 13 H 13 ] 2À is strongly bonding with respect to the 1-2 and 1-3 edges,a nd moderately strongly bonding with respect to the 6-9 and 7-8 edges. [15,16] Thef astest moving band (identified as purple compound 3), the third fastest band (dark green compound 4), and the sixth fastest moving band (purple compound 5)w ere also studied, with elemental analysis and/or mass spectrometry suggesting the formula [(Cp*Ru) 2 C 2 B 10 H 12 ]for all three.T he 1 HNMR spectra of 3-5 contain one relatively high frequency C cage H resonance signal (d = 8.6 to 10.5 ppm) and two resonance signals corresponding to the Cp* Ha toms.T he asymmetry of all three compounds is confirmed by their 11 BNMR spectra which exhibit ten equal-integral resonance signals for 4 and 5 and nine resonance signals for 3 (one less signal as aresult of the overlapping of two signals). [15,16] Thef astest moving band (identified as purple compound 3), the third fastest band (dark green compound 4), and the sixth fastest moving band (purple compound 5)w ere also studied, with elemental analysis and/or mass spectrometry suggesting the formula [(Cp*Ru) 2 C 2 B 10 H 12 ]for all three.T he 1 HNMR spectra of 3-5 contain one relatively high frequency C cage H resonance signal (d = 8.6 to 10.5 ppm) and two resonance signals corresponding to the Cp* Ha toms.T he asymmetry of all three compounds is confirmed by their 11 BNMR spectra which exhibit ten equal-integral resonance signals for 4 and 5 and nine resonance signals for 3 (one less signal as aresult of the overlapping of two signals).…”

The Mechanism of Reduction and Metalation of para Carboranes: The Missing 13‐Vertex MC2B10 Isomer

“…[7] However, the directions of all these isomerizations are fully consistent with the calculated energies of (h-C 6 H 6 )RuC 2 B 10 H 12 in its various 4,1,xRuC 2 B 10 isomeric forms, also shown in Scheme 2 (DFT, in kcal mol À1 relative to 4-(h-C 6 H 6 )-4,1,6-closo-RuC 2 B 10 H 12 ). [14] In conclusion, we have isolated and characterized the first example of a 4,1,11-MC 2 B 10 We have suggested that these nido carboranes then isomerize to three other isomers, and that metalations of all these account for the five metallacarboranes isolated. It therefore appears that the reduction of para carborane is much more complicated than previous studies have suggested.…”