Stabilisation of high oxidation-state niobium using ‘electron-rich’ bicyclic-guanidinates
| Autor: | Joanna Grundy, D.B. Soria, Martyn P. Coles, Peter B. Hitchcock |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Bicyclic molecule
Ligand Organic Chemistry Inorganic chemistry chemistry.chemical_element Crystal structure Biochemistry Inorganic Chemistry Transmetalation chemistry.chemical_compound chemistry Oxidation state Polymer chemistry Materials Chemistry Molecule Lithium Physical and Theoretical Chemistry Acetonitrile |
| Zdroj: | Journal of Organometallic Chemistry. 690:2278-2284 |
| ISSN: | 0022-328X |
| Popis: | Synthetic procedures to high oxidation-state complexes of niobium incorporating the bicyclic guanidinate 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate, [hpp]?, are described. The ligand source was either the N-trimethylsilylated guanidine or the lithium guanidinate and the reaction proceeded via elimination of trimethylsilylchloride or transmetallation from NbCl5, respectively. A 1:1 ratio of reagents afforded the mono-ligand product, Nb(hpp)Cl4 (1) and crystallisation from acetonitrile afforded the solvated species Nb(hpp)Cl4(MeCN) (1a), demonstrating the ability of the metal centre in 1 to bind small substrate molecules. A 2:1 ratio of lithium guanidinate to NbCl5 resulted in formation of the seven-coordinate, bis-ligand compound, Nb(hpp)2Cl3 (2). These products represent the first examples of guanidinate compounds in which niobium is stable in the +5 oxidation-state, believed to result from enhanced electron donation caused by the bicyclic framework of the ligand. The molecular structures of 1, 1a and 2 are reported, presenting for the first time an opportunity to describe bonding parameters within compounds of this type. |
| Databáze: | OpenAIRE |
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