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Neutral and Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Complexes: Reactivity in Selected Olefin Metathesis Reactions and Immobilization on Silica.
- Source :
-
Chemistry - A European Journal . Sep2015, Vol. 21 Issue 39, p13778-13787. 10p. - Publication Year :
- 2015
-
Abstract
- The synthesis and single-crystal X-ray structures of the novel molybdenum imido alkylidene N-heterocyclic carbene complexes [Mo(N-2,6-Me2C6H3)(IMesH2)(CHCMe2Ph)(OTf)2] ( 3), [Mo(N-2,6-Me2C6H3)(IMes)(CHCMe2Ph)(OTf)2] ( 4), [Mo(N-2,6-Me2C6H3)(IMesH2)(CHCMe2Ph)(OTf){OCH(CF3)2}] ( 5), [Mo(N-2,6-Me2C6H3)(CH3CN)(IMesH2)(CHCMe2Ph)(OTf)]+ BArF− ( 6), [Mo(N-2,6-Cl2C6H3)(IMesH2)(CHCMe3)(OTf)2] ( 7) and [Mo(N-2,6-Cl2C6H3)(IMes)(CHCMe3)(OTf)2] ( 8) are reported (IMesH2=1,3-dimesitylimidazolidin-2-ylidene, IMes=1,3-dimesitylimidazolin-2-ylidene, BArF−=tetrakis-[3,5-bis(trifluoromethyl)phenyl] borate, OTf=CF3SO3−). Also, silica-immobilized versions I1 and I2 were prepared. Catalysts 3- 8, I1 and I2 were used in homo-, cross-, and ring-closing metathesis (RCM) reactions and in the cyclopolymerization of α,ω-diynes. In the RCM of α,ω-dienes, in the homometathesis of 1-alkenes, and in the ethenolysis of cyclooctene, turnover numbers (TONs) up to 100 000, 210 000 and 30 000, respectively, were achieved. With I1 and I2, virtually Mo-free products were obtained (<3 ppm Mo). With 1,6-hepta- and 1,7-octadiynes, catalysts 3, 4, and 5 allowed for the regioselective cyclopolymerization of 4,4-bis(ethoxycarbonyl)-1,6-heptadiyne, 4,4-bis(hydroxymethyl)-1,6-heptadiyne, 4,4-bis[(3,5-diethoxybenzoyloxy)methyl]-1,6-heptadiyne, 4,4,5,5-tetrakis(ethoxycarbonyl)-1,7-octadiyne, and 1,6-heptadiyne-4-carboxylic acid, underlining the high functional-group tolerance of these novel Group 6 metal alkylidenes. [ABSTRACT FROM AUTHOR]
- Subjects :
- *MOLYBDENUM compounds
*IMIDES
*ALKYLIDENES
*CARBENES
*HETEROCYCLIC compounds
Subjects
Details
- Language :
- English
- ISSN :
- 09476539
- Volume :
- 21
- Issue :
- 39
- Database :
- Academic Search Index
- Journal :
- Chemistry - A European Journal
- Publication Type :
- Academic Journal
- Accession number :
- 109365318
- Full Text :
- https://doi.org/10.1002/chem.201501615