| Steric control of coordination geometry in titanium-imido complexes of N,N'-bis(arylimino)acenaphthylene ligands. | |
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MedLine Citation:
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PMID: 20170200 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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Titanium complexes of N,N'-bis(arylimino)acenaphthylene (BIAN) alpha-diimine ligands with varied steric profiles have been prepared. Coordination of the BIAN ligand derivatives to TiCl(4) afforded the adducts (dpp-BIAN)TiCl(4) (1a), (tmp-BIAN)TiCl(4) (1b), and (dmp-BIAN)TiCl(4) (1c) (dpp = 2,6-diisopropylphenyl; tmp = 2,4,6-trimethylphenyl; dmp = 3,5-dimethylphenyl). While the least sterically crowded complex 1c is robust toward loss of the diimine ligand, the dpp-BIAN and tmp-BIAN ligands are readily displaced by pyridine from the more crowded derivatives 1a and 1b, respectively. The crowded profiles engendered by the tmp-BIAN and dpp-BIAN ligands result in the formation of five-coordinate titanium-imide complexes, (dpp-BIAN)TiCl(2)(=N(t)Bu) (2a) and (tmp-BIAN)TiCl(2)(=N(t)Bu) (2b), upon addition of (t)BuNH(2) to solutions of 1a or 1b, respectively. Single-crystal X-ray diffraction studies reveal a square pyramidal coordination environment with an apical imide ligand and a short Ti-N distance, consistent with a Ti-N triple bond. Conversely, the less crowded dmp-BIAN ligand affords a six-coordinate titanium imido complex, (dmp-BIAN)TiCl(2)(=N(t)Bu)(NH(2)(t)Bu) (4), upon treatment of 1c with (t)BuNH(2). Surprisingly the imido ligand is coordinated trans to one arm of the diimine. This six coordinate species is fluxional in solution, and exchange and variable temperature (1)H NMR experiments suggest dissociation of the coordinated (t)BuNH(2) ligand to generate a five-coordinate imido intermediate analogous to 2a and 2b. |
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Authors:
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Kensha Marie Clark; Joseph W Ziller; Alan F Heyduk |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Inorganic chemistry Volume: 49 ISSN: 1520-510X ISO Abbreviation: Inorg Chem Publication Date: 2010 Mar |
Date Detail:
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Created Date: 2010-02-22 Completed Date: 2010-05-20 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0366543 Medline TA: Inorg Chem Country: United States |
Other Details:
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Languages: eng Pagination: 2222-31 Citation Subset: - |
Affiliation:
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Department of Chemistry, University of California, Irvine, California 92697, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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