Qualitatively Different Reactivities of Hydride Reagents toward (a-diimine)(h5-C5Me5)ClIr+ Cations: Substitution, Electron Transfer (Reduction), or Stepwise Hydrogenation

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Organometallics, 21 (4): 765--769 (2002)
DOI: 10.1021/om010529k


Whereas complex cations (a-diimine)(h5-C5Me5)ClIr+ with 2,2'-bipyridine and related arom. ligands show only the expected Cl/H exchange on reaction with borohydrides, the systems (RN:CHCH:NR)(h5-C5Me5)ClIr+ undergo redn. to the enediamido(2-)-Ir(III) species (RNCH:CHNR)(h5-C5Me5)Ir, even in protic media, if R is an axially shielding 2,6-dialkylphenyl group. In protic media the complex ion with R = cyclohexyl undergoes Cl/H exchange and stepwise hydrogenation of the a-diimine ligand via (RHNCH2CH:NR)(h5-C5Me5)HIr(PF6) to the structurally characterized compd. (RHNCH2CH2NHR)(h5-C5Me5)HIrBH3(CN). Results of cyclic voltammetry studies are also presented. The crystal and mol. structures of (RN:CHCH:NR)(h5-C5Me5)ClIr(PF6) (R = o-tolyl) and (RHNCH2CH2NHR)(h5-C5Me5)HIrBH3(CN) (R = cyclohexyl) were detd. by x-ray crystallog. on SciFinder(R)



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