Homoleptic permethylpentalene complexes: "double metallocenes" of the first-row transition metals.
The synthesis of the bimetallic permethylpentalene complexes Pn*2M2 (M = V, Cr, Mn, Co, Ni; Pn* = C8Me6) has been accomplished, and all of the complexes have been structurally characterized in the solid state by single-crystal X-ray diffraction. Pn*2V2 (1) and Pn*2Mn2 (3) show very short intermetall...
| Main Authors: | , , , , |
|---|---|
| Format: | Journal article |
| Language: | English |
| Published: |
2008
|
| _version_ | 1797060874799677440 |
|---|---|
| author | Ashley, A Cooper, RT Wildgoose, G Green, J O'Hare, D |
| author_facet | Ashley, A Cooper, RT Wildgoose, G Green, J O'Hare, D |
| author_sort | Ashley, A |
| collection | OXFORD |
| description | The synthesis of the bimetallic permethylpentalene complexes Pn*2M2 (M = V, Cr, Mn, Co, Ni; Pn* = C8Me6) has been accomplished, and all of the complexes have been structurally characterized in the solid state by single-crystal X-ray diffraction. Pn*2V2 (1) and Pn*2Mn2 (3) show very short intermetallic distances that are consistent with metal-metal bonding, while the cobalt centers in Pn*2Co2 (4) exhibit differential bonding to each side of the Pn* ligand that is consistent with an eta(5):eta(3) formulation. The Pn* ligands in Pn*2Ni2 (5) are best described as eta(3):eta(3)-bonded to the metal centers. (1)H NMR studies indicate that all of the Pn*2M2 species exhibit D(2h) molecular symmetry in the solution phase; the temperature variation of the chemical shifts for the resonances of Pn*2Cr2 (2) indicates that the molecule has an S = 0 ground state and a thermally populated S = 1 excited state and can be successfully modeled using a Boltzmann distribution (DeltaH(o) = 14.9 kJ mol(-1) and DeltaS(o) = 26.5 J K(-1) mol(-1)). The solid-state molar magnetic susceptibility of 3 obeys the Curie-Weiss law with mu(eff) = 2.78 muB and theta = -1.0 K; the complex is best described as having an S = 1 electronic ground state over the temperature range 4-300 K. Paradoxically, attempts to isolate the "double ferrocene" equivalent, Pn*2Fe2, led only to the isolation of the permethylpentalene dimer Pn*2 (6). Solution electrochemical studies were performed on all of the organometallic compounds; 2-5 exhibit multiple quasi-reversible redox processes. Density functional theory calculations were performed on this series of complexes in order to rationalize the observed structural and spectroscopic data and provide estimates of the M-M bond orders. |
| first_indexed | 2024-03-06T20:23:06Z |
| format | Journal article |
| id | oxford-uuid:2e80de55-0376-4acd-81cc-423b14b21d1e |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T20:23:06Z |
| publishDate | 2008 |
| record_format | dspace |
| spelling | oxford-uuid:2e80de55-0376-4acd-81cc-423b14b21d1e2022-03-26T12:49:22ZHomoleptic permethylpentalene complexes: "double metallocenes" of the first-row transition metals.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:2e80de55-0376-4acd-81cc-423b14b21d1eEnglishSymplectic Elements at Oxford2008Ashley, ACooper, RTWildgoose, GGreen, JO'Hare, DThe synthesis of the bimetallic permethylpentalene complexes Pn*2M2 (M = V, Cr, Mn, Co, Ni; Pn* = C8Me6) has been accomplished, and all of the complexes have been structurally characterized in the solid state by single-crystal X-ray diffraction. Pn*2V2 (1) and Pn*2Mn2 (3) show very short intermetallic distances that are consistent with metal-metal bonding, while the cobalt centers in Pn*2Co2 (4) exhibit differential bonding to each side of the Pn* ligand that is consistent with an eta(5):eta(3) formulation. The Pn* ligands in Pn*2Ni2 (5) are best described as eta(3):eta(3)-bonded to the metal centers. (1)H NMR studies indicate that all of the Pn*2M2 species exhibit D(2h) molecular symmetry in the solution phase; the temperature variation of the chemical shifts for the resonances of Pn*2Cr2 (2) indicates that the molecule has an S = 0 ground state and a thermally populated S = 1 excited state and can be successfully modeled using a Boltzmann distribution (DeltaH(o) = 14.9 kJ mol(-1) and DeltaS(o) = 26.5 J K(-1) mol(-1)). The solid-state molar magnetic susceptibility of 3 obeys the Curie-Weiss law with mu(eff) = 2.78 muB and theta = -1.0 K; the complex is best described as having an S = 1 electronic ground state over the temperature range 4-300 K. Paradoxically, attempts to isolate the "double ferrocene" equivalent, Pn*2Fe2, led only to the isolation of the permethylpentalene dimer Pn*2 (6). Solution electrochemical studies were performed on all of the organometallic compounds; 2-5 exhibit multiple quasi-reversible redox processes. Density functional theory calculations were performed on this series of complexes in order to rationalize the observed structural and spectroscopic data and provide estimates of the M-M bond orders. |
| spellingShingle | Ashley, A Cooper, RT Wildgoose, G Green, J O'Hare, D Homoleptic permethylpentalene complexes: "double metallocenes" of the first-row transition metals. |
| title | Homoleptic permethylpentalene complexes: "double metallocenes" of the first-row transition metals. |
| title_full | Homoleptic permethylpentalene complexes: "double metallocenes" of the first-row transition metals. |
| title_fullStr | Homoleptic permethylpentalene complexes: "double metallocenes" of the first-row transition metals. |
| title_full_unstemmed | Homoleptic permethylpentalene complexes: "double metallocenes" of the first-row transition metals. |
| title_short | Homoleptic permethylpentalene complexes: "double metallocenes" of the first-row transition metals. |
| title_sort | homoleptic permethylpentalene complexes double metallocenes of the first row transition metals |
| work_keys_str_mv | AT ashleya homolepticpermethylpentalenecomplexesdoublemetallocenesofthefirstrowtransitionmetals AT cooperrt homolepticpermethylpentalenecomplexesdoublemetallocenesofthefirstrowtransitionmetals AT wildgooseg homolepticpermethylpentalenecomplexesdoublemetallocenesofthefirstrowtransitionmetals AT greenj homolepticpermethylpentalenecomplexesdoublemetallocenesofthefirstrowtransitionmetals AT ohared homolepticpermethylpentalenecomplexesdoublemetallocenesofthefirstrowtransitionmetals |