Insertion reactions of dicyclohexylcarbodiimide with aminoboranes, -boryls and -borylenes.
Insertion reactions of dicyclohexylcarbodiimide with aminoboranes and with aminoboryl and -borylene transition metal complexes have been examined as potential routes to new boron-containing ligand systems. Reactions with systems containing two-coordinate boron centres are found to be significantly m...
| Main Authors: | , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2007
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| _version_ | 1826272453427462144 |
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| author | Pierce, G Coombs, N Willock, D Day, J Stasch, A Aldridge, S |
| author_facet | Pierce, G Coombs, N Willock, D Day, J Stasch, A Aldridge, S |
| author_sort | Pierce, G |
| collection | OXFORD |
| description | Insertion reactions of dicyclohexylcarbodiimide with aminoboranes and with aminoboryl and -borylene transition metal complexes have been examined as potential routes to new boron-containing ligand systems. Reactions with systems containing two-coordinate boron centres are found to be significantly more facile than those with three-coordinate substrates. Thus, reaction of (dicyclohexylamino)boron dichloride () with dicyclohexylcarbodiimide over 36 h at 50 degrees C generates the (structurally authenticated) guanidinate complex Cy(2)NC(NCy)(2)BCl(2) () via insertion into the BN bond. By contrast, the corresponding reaction with the cationic aminoborylene complex [CpFe(CO)(2)(BNCy(2))](+)[BAr(f)(4)](-) () proceeds rapidly at ca.-30 degrees C, via initial insertion into the FeB bond to give [CpFe(CO)(2)C(NCy)(2)BNCy(2)](+)[BAr(f)(4)](-) (). Consistent with related studies, a key factor in facilitating such insertion chemistry is thought to be the formation of an initial donor/acceptor complex between the diimide and the group 13 centre. Thus, DFT studies suggest that [CpFe(CO)(2)B(NCy(2))(CyNCNCy)](+)[BAr(f)(4)](-) is a potential intermediate in the reaction of with CyNCNCy, and that further reaction to give the observed product, , is strongly exergic (-183 kJ mol(-1)). By contrast, DFT calculations for the alternative isomer [CpFe(CO)(2)B(CyN)(2)CNCy(2)](+)[BAr(f)(4)](-) (), formed by BN insertion, suggest that it is 112 kJ mol(-1) less stable than . Such experimental and computational findings imply that under reaction conditions where a suitable isomerisation pathway is available, cationic complexes such as , which contain a four-membered boron-donor heterocycle are likely to be disfavoured with respect to alternative C-bound isomers. |
| first_indexed | 2024-03-06T22:12:49Z |
| format | Journal article |
| id | oxford-uuid:52638ee6-be4a-49fc-859e-99175e931b81 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T22:12:49Z |
| publishDate | 2007 |
| record_format | dspace |
| spelling | oxford-uuid:52638ee6-be4a-49fc-859e-99175e931b812022-03-26T16:25:16ZInsertion reactions of dicyclohexylcarbodiimide with aminoboranes, -boryls and -borylenes.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:52638ee6-be4a-49fc-859e-99175e931b81EnglishSymplectic Elements at Oxford2007Pierce, GCoombs, NWillock, DDay, JStasch, AAldridge, SInsertion reactions of dicyclohexylcarbodiimide with aminoboranes and with aminoboryl and -borylene transition metal complexes have been examined as potential routes to new boron-containing ligand systems. Reactions with systems containing two-coordinate boron centres are found to be significantly more facile than those with three-coordinate substrates. Thus, reaction of (dicyclohexylamino)boron dichloride () with dicyclohexylcarbodiimide over 36 h at 50 degrees C generates the (structurally authenticated) guanidinate complex Cy(2)NC(NCy)(2)BCl(2) () via insertion into the BN bond. By contrast, the corresponding reaction with the cationic aminoborylene complex [CpFe(CO)(2)(BNCy(2))](+)[BAr(f)(4)](-) () proceeds rapidly at ca.-30 degrees C, via initial insertion into the FeB bond to give [CpFe(CO)(2)C(NCy)(2)BNCy(2)](+)[BAr(f)(4)](-) (). Consistent with related studies, a key factor in facilitating such insertion chemistry is thought to be the formation of an initial donor/acceptor complex between the diimide and the group 13 centre. Thus, DFT studies suggest that [CpFe(CO)(2)B(NCy(2))(CyNCNCy)](+)[BAr(f)(4)](-) is a potential intermediate in the reaction of with CyNCNCy, and that further reaction to give the observed product, , is strongly exergic (-183 kJ mol(-1)). By contrast, DFT calculations for the alternative isomer [CpFe(CO)(2)B(CyN)(2)CNCy(2)](+)[BAr(f)(4)](-) (), formed by BN insertion, suggest that it is 112 kJ mol(-1) less stable than . Such experimental and computational findings imply that under reaction conditions where a suitable isomerisation pathway is available, cationic complexes such as , which contain a four-membered boron-donor heterocycle are likely to be disfavoured with respect to alternative C-bound isomers. |
| spellingShingle | Pierce, G Coombs, N Willock, D Day, J Stasch, A Aldridge, S Insertion reactions of dicyclohexylcarbodiimide with aminoboranes, -boryls and -borylenes. |
| title | Insertion reactions of dicyclohexylcarbodiimide with aminoboranes, -boryls and -borylenes. |
| title_full | Insertion reactions of dicyclohexylcarbodiimide with aminoboranes, -boryls and -borylenes. |
| title_fullStr | Insertion reactions of dicyclohexylcarbodiimide with aminoboranes, -boryls and -borylenes. |
| title_full_unstemmed | Insertion reactions of dicyclohexylcarbodiimide with aminoboranes, -boryls and -borylenes. |
| title_short | Insertion reactions of dicyclohexylcarbodiimide with aminoboranes, -boryls and -borylenes. |
| title_sort | insertion reactions of dicyclohexylcarbodiimide with aminoboranes boryls and borylenes |
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