NH-Tautomerization of Quinolines and 2-Methylpyridine Promoted by a Hydride-Iridium(III) Complex: Importance of the Hydride Ligand

作者：Esteruelas Miguel A^*; Fernandez Alvarez Francisco J; Olivan Montserrat; Onate Enrique

来源：Organometallics, 2009, 28(7): 2276-2284.

DOI：10.1021/om8011954

The reactions of the iridium complexes IrHCl(2)(P(i)Pr(3))(2) (1) and IrCl(eta(2)-C(8)H(14))(P(i)Pr(3))(2) (2) with quinoline, 8-methylquinoline, 2-methylpyridine and benzo[h]quinoline (Hbq) have been studied. Complex 1 promotes the NH-tautomerization of quinoline and 8-methylquinoline and stabilizes the resulting NH-tautomers to afford IrHCl(2){kappa-C-(HNC(9)H(6))}(P(i)Pr(3))(2) (3) and IrHCl(2){kappa-C-(HNC(9)H(5)CH(3))}(P(i)Pr(3))(2) (4), while the respective reactions of 2 lead toIrH{CH(2)CH(CH(3))P(i)Pr(2)}Cl{kappa-N-(NC(9)H(7))}(P(i)Pr(3)) (5) and IrHCl(CH(2)C(9)H(6)N)(P(i)Pr(3))(2) (6). Complex 1 also tautomerizes 2-methylpyridine and stabilizes the resulting tautomer to give IrHCl(2) {kappa-C-(HNC(5)H(3)CH(3))} (P(i)Pr(3))(2) (7). However, in the presence of 2, the tautomerization does not occur. Treatment of 2 with 2-methylpyridine leads to a mixture of unidentified nontautomer derivatives. The products from the reactions of I with benzo[h]quinoline depend upon the metal/heterocycle ratios used. Treatment of 1 with 1.2 equiv of benzo[h]quinoline leads to the NH-tautomer derivative IrHCl(2){kappa-C-(HNbq))(P(i)Pr(3))(2) (8; 15%) and the metalated species IrHCl{kappa-N,C-(bq))(P(i)Pr(3))(2) (9; 85%). However, when a 1:3 molar ratio is used, 9 (60%) and the salt [HNHbq][IrHCl(3)(P(i)Pr(3))(2)] (10, 40%; HNHbq = benzo[h]quinolinium) are formed. Complexes 4, 5, 6, 7, 9, and 10 have been characterized by X-ray diffraction analysis. The mechanism of the NH-tautomeration is also reported.

• 出版日期2009-4-13