2024-03-28T22:47:23Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1114952016-02-18T00:37:58Zcom_10261_52707com_10261_5col_10261_52708
Terminal and bridging parent amido 1,5-cyclooctadiene complexes of rhodium and iridium
Mena, Inmaculada
Jaseer, E. A.
Casado, Miguel A.
García-Orduña, P.
Lahoz, Fernando J.
Oro, Luis A.
Factoría Española de Cristalización
Consejo Superior de Investigaciones Científicas (España)
European Commission
Ministry of Education - Higher Education (Saudi Arabia)
King Fahd University of Petroleum and Minerals
Parent amido
Iridium
Hydrogen transfer
Rhodium
Cyclooctadienyl ligands
The ready availability of rare parent amido d8 complexes of the type [{M(μ-NH2)(cod)}2] (M=Rh (1), Ir (2); cod=1,5-cyclooctadiene) through the direct use of gaseous ammonia has allowed the study of their reactivity. Both complexes 1 and 2 exchanged the di-olefines by carbon monoxide to give the dinuclear tetracarbonyl derivatives [{M(μ-NH2)(CO)2}2] (M=Rh or Ir). The diiridium(I) complex 2 reacted with chloroalkanes such as CH2Cl 2 or CHCl3, giving the diiridium(II) products [(Cl)(cod)Ir(μ-NH2)2Ir(cod)(R)] (R=CH2Cl or CHCl2) as a result of a two-center oxidative addition and concomitant metal-metal bond formation. However, reaction with ClCH2CH 2Cl afforded the symmetrical adduct [{Ir(μ-NH2)(Cl) (cod)}2] upon release of ethylene. We found that the rhodium complex 1 exchanged the di-olefines stepwise upon addition of selected phosphanes (PPh3, PMePh2, PMe2Ph) without splitting of the amido bridges, allowing the detection of mixed COD/phosphane dinuclear complexes [(cod)Rh(μ-NH2)2Rh(PR3) 2], and finally the isolation of the respective tetraphosphanes [{Rh(μ-NH2)(PR3)2}2]. On the other hand, the iridium complex 2 reacted with PMe2Ph by splitting the amido bridges and leading to the very rare terminal amido complex [Ir(cod)(NH2)(PMePh2)2]. This compound was found to be very reactive towards traces of water, giving the more stable terminal hydroxo complex [Ir(cod)(OH)(PMePh2)2]. The heterocyclic carbene IPr (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) also split the amido bridges in complexes 1 and 2, allowing in the case of iridium to characterize in situ the terminal amido complex [Ir(cod)(IPr)(NH 2)]. However, when rhodium was involved, the known hydroxo complex [Rh(cod)(IPr)(OH)] was isolated as final product. On the other hand, we tested complexes 1 and 2 as catalysts in the transfer hydrogenation of acetophenone with iPrOH without the use of any base or in the presence of Cs2CO3, finding that the iridium complex 2 is more active than the rhodium analogue 1.
2015-02-27T11:18:40Z
2015-02-27T11:18:40Z
2013
2015-02-27T11:18:41Z
artículo
Chemistry - A European Journal 19(18): 5665-5675 (2013)
http://hdl.handle.net/10261/111495
10.1002/chem.201204391
http://dx.doi.org/10.13039/501100003339
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100004055
eng
Sí
closedAccess
Wiley-VCH