Synthesis, Structure, and Ligand Exchange Reactions of Tetramethyleneethane Complexes of Cobalt
The synthesis of (η3:η3-TME)[Co(CO) 3]2 (1) was achieved using 2,3-bis(bromomethyl)-1,3- butadiene (TMEBr2) as the tetramethyleneethane (TME) ligand precursor and Na[Co(CO)4]. Solution NMR studies suggested an η3:η3-configuration, which has been confirmed in the solid state by single-crystal X-ray d...
| Main Authors: | , , , , , , |
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| Format: | Journal article |
| Language: | English |
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2010
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| _version_ | 1797066573435895808 |
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| author | Aguirre-Etcheverry, P Ashley, A Balazs, G Green, J Cowley, A Thompson, A O'Hare, D |
| author_facet | Aguirre-Etcheverry, P Ashley, A Balazs, G Green, J Cowley, A Thompson, A O'Hare, D |
| author_sort | Aguirre-Etcheverry, P |
| collection | OXFORD |
| description | The synthesis of (η3:η3-TME)[Co(CO) 3]2 (1) was achieved using 2,3-bis(bromomethyl)-1,3- butadiene (TMEBr2) as the tetramethyleneethane (TME) ligand precursor and Na[Co(CO)4]. Solution NMR studies suggested an η3:η3-configuration, which has been confirmed in the solid state by single-crystal X-ray diffraction studies. The series of complexes (η3:η3-TME)[Co(CO)2PR 3]2 (R = Me, 2; R = Et, 3; R = n-Bu, 4; R = Ph, 5; R = OPh, 6) were also synthesized by ligand exchange reactions, demonstrating that only one carbonyl may be exchanged for a phosphine group on each metal center. The η3:η3-configuration of the tetramethyleneethane ligand in these complexes was determined by crystallographic studies. The effect of the electron-donating properties of PR3 was studied by cyclic voltammetry (CV) and infrared spectroscopy. The greatest degree of electron donation was seen when R = Et (3) and lowest when R = Ph (5) or R = OPh (6). Electronic communication between the metal centers was observed by CV. The chemical oxidation of 1 resulted in a highly unstable species that decomposed to {[(CO)2Co]TME[Co(CO) 3]}+[BF4]- (1+d), determined by its crystal structure. The synthesis of (η4: η4-TME)[CoCp*]2 (7) has been achieved using a dipotassium 2,3-bis(methylene)-1,3-butanediyl (TMEK2) synthon. NMR studies suggested that 7 adopts an unusual η4:η4- configuration, which was confirmed with the aid of crystallographic studies. DFT calculations were performed in order to rationalize the bonding for 1, 7, and hypothetical (η4:η4-TME)[CoCp]2 (8). The large energy difference between the two coordination isomers 1 and 1a confirmed the η3:η3-configuration. For isomers 7/7a and 8/8a, the energy difference between the two isomers (ca. 15 kJ mol -1) is in favor of the η4:η4- configuration. For complexes 1+ and 8+, the calculations suggested complete delocalization on the system when one electron was removed. © 2010 American Chemical Society. |
| first_indexed | 2024-03-06T21:44:00Z |
| format | Journal article |
| id | oxford-uuid:48eb77fc-8eef-4a8a-9808-062d394b06ee |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T21:44:00Z |
| publishDate | 2010 |
| record_format | dspace |
| spelling | oxford-uuid:48eb77fc-8eef-4a8a-9808-062d394b06ee2022-03-26T15:28:37ZSynthesis, Structure, and Ligand Exchange Reactions of Tetramethyleneethane Complexes of CobaltJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:48eb77fc-8eef-4a8a-9808-062d394b06eeEnglishSymplectic Elements at Oxford2010Aguirre-Etcheverry, PAshley, ABalazs, GGreen, JCowley, AThompson, AO'Hare, DThe synthesis of (η3:η3-TME)[Co(CO) 3]2 (1) was achieved using 2,3-bis(bromomethyl)-1,3- butadiene (TMEBr2) as the tetramethyleneethane (TME) ligand precursor and Na[Co(CO)4]. Solution NMR studies suggested an η3:η3-configuration, which has been confirmed in the solid state by single-crystal X-ray diffraction studies. The series of complexes (η3:η3-TME)[Co(CO)2PR 3]2 (R = Me, 2; R = Et, 3; R = n-Bu, 4; R = Ph, 5; R = OPh, 6) were also synthesized by ligand exchange reactions, demonstrating that only one carbonyl may be exchanged for a phosphine group on each metal center. The η3:η3-configuration of the tetramethyleneethane ligand in these complexes was determined by crystallographic studies. The effect of the electron-donating properties of PR3 was studied by cyclic voltammetry (CV) and infrared spectroscopy. The greatest degree of electron donation was seen when R = Et (3) and lowest when R = Ph (5) or R = OPh (6). Electronic communication between the metal centers was observed by CV. The chemical oxidation of 1 resulted in a highly unstable species that decomposed to {[(CO)2Co]TME[Co(CO) 3]}+[BF4]- (1+d), determined by its crystal structure. The synthesis of (η4: η4-TME)[CoCp*]2 (7) has been achieved using a dipotassium 2,3-bis(methylene)-1,3-butanediyl (TMEK2) synthon. NMR studies suggested that 7 adopts an unusual η4:η4- configuration, which was confirmed with the aid of crystallographic studies. DFT calculations were performed in order to rationalize the bonding for 1, 7, and hypothetical (η4:η4-TME)[CoCp]2 (8). The large energy difference between the two coordination isomers 1 and 1a confirmed the η3:η3-configuration. For isomers 7/7a and 8/8a, the energy difference between the two isomers (ca. 15 kJ mol -1) is in favor of the η4:η4- configuration. For complexes 1+ and 8+, the calculations suggested complete delocalization on the system when one electron was removed. © 2010 American Chemical Society. |
| spellingShingle | Aguirre-Etcheverry, P Ashley, A Balazs, G Green, J Cowley, A Thompson, A O'Hare, D Synthesis, Structure, and Ligand Exchange Reactions of Tetramethyleneethane Complexes of Cobalt |
| title | Synthesis, Structure, and Ligand Exchange Reactions of Tetramethyleneethane Complexes of Cobalt |
| title_full | Synthesis, Structure, and Ligand Exchange Reactions of Tetramethyleneethane Complexes of Cobalt |
| title_fullStr | Synthesis, Structure, and Ligand Exchange Reactions of Tetramethyleneethane Complexes of Cobalt |
| title_full_unstemmed | Synthesis, Structure, and Ligand Exchange Reactions of Tetramethyleneethane Complexes of Cobalt |
| title_short | Synthesis, Structure, and Ligand Exchange Reactions of Tetramethyleneethane Complexes of Cobalt |
| title_sort | synthesis structure and ligand exchange reactions of tetramethyleneethane complexes of cobalt |
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