The chemistry of the tantalum dinitrogen complex ([NPN]Ta)₂(μ-H)₂(μ-η¹:η²-N₂)Ta-[NPN], 1, (where [NPN] represents the acyclic tridentate ligand [(PhNSiMe₂CH₂)₂-PPh]²-), with primary alkenes, group IV and V metallocene complexes, and GaCp* is explored.
The reaction of 1 with 1-pentene and 1-hexene occurs via olefin-insertion into the metal-hydride bond to give two new complexes, ([NPN]Ta(CH₂)₄CH₃)₂(μ-η¹:η¹-N₂), 10, and ([NPN]Ta(CH₂)₅CH₃)₂(μ-η¹:η¹-N₂), 11, which were characterized using NMR spectroscopy. The solid-state structure of 11 was established and revealed that N₂ has been transformed into a bridging end-on mode. In contrast to its G symmetry in solution, the solid-state structure of 11 is C, symmetric; a VT-NMR study was performed and showed that 11 exists as an equilibrium between two isomers in solution: a C, symmetric isomer 11A,which is the predominant isomer at room temperature, and a C, symmetric isomer 11B,which is the minor isomer.
The reactivity of 1 with group IV and V metallocenes was investigated. The reaction of 1 with Cp₂Hf(PMe₃)(η²-Me₃SiCCSiMe₃) produces [N(μ-P=N)N]Ta(μ-H)₂(μ-N(Hf-Cp₂))Ta[NPN], 14, in which N₂ is cleaved and new Hf-N and P=N bonds have formed. The reaction of 1 with group V metallocene hydrides Cp₂MH₃ (M Nb, Ta) was also attempted however these complexes do not react with 1.
The reaction of 1 with GaCp* produces a new complex, [NPN]Ta(μ-N(GaCp*))Ta(=NPμ)[NPIA,-N], 18, which was characterized using NMR spectroscopy. Complex 18 decomposes over several days in solution, and one product of decomposition that was isolated was [(PhNH)(NPμ-N)Ta]₂, 19. The solid-state structure of 19 showed that the [NPN] ligand was cleaved at the N-Si bond, similar to that observed for the reaction of 1 with 9-BBN and HB(C₆H₅)₂. A mechanism for the formation of complexes 18 and 19 is proposed.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/2344 |
| Date | 11 1900 |
| Creators | Park, Rosa |
| Publisher | University of British Columbia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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