Dipartimento di Chimica, Fisica e Ambiente, Università di Udine, Via Cotonificio 108, I-33100, Udine, Italy.
Dalton Trans. 2011 Sep 21;40(35):8986-95. doi: 10.1039/c1dt10498e. Epub 2011 Jun 21.
The pincer complexes [MX(CNN)(PP)] (M = Ru, Os; X = Cl, OTf; HCNN = 1-(6-arylpyridin-2-yl)methanamine; PP = diphosphine) have proven to efficiently catalyze both racemization and deuteration of alcohols in the presence of a base. Chiral alcohols have been racemized at 30-50 °C using 1 mol% of Ru or Os pincer complexes and 5 mol% of KOtBu in 2-propanol. Primary and secondary alcohols are efficiently deuterated at the α position, with respect to the OH group, using 2-propanol-d(8) as solvent with Ru or Os pincer complexes and KOtBu at 30-50 °C. For secondary alcohols incorporation of deuterium at the β position has also been observed. In 2-propanol-d(8) the pincer complexes catalyze the simultaneous deuteration and racemization of (S)-1-phenylethanol, the two processes being strictly correlated. For both reactions much the same activity has been observed with the Ru and Os complexes. The pincer complexes display a superior activity with respect to the related compounds [MCl(2)(NN)(PP)] (NN = bidentate amine or pyridine ligand). The synthesis of the new complexes [MCl(CNN)(PP)] (M = Ru, 2, 4 and Os, 6, 7; PP = dppb, dppf) and [Ru(OTf)(CNN)(dppb)] (3) is also reported.
钳形配合物[MX(CNN)(PP)]（M=Ru，Os；X=Cl，OTf；HCNN=1-(6-芳基吡啶-2-基)甲胺；PP=双膦）已被证明在碱存在下能有效地催化醇的外消旋化和氘代反应。在 2-丙醇中，使用 1 mol%的 Ru 或 Os 钳形配合物和 5 mol%的 KOtBu，30-50°C 下可使手性醇外消旋化。使用 2-丙醇-d(8)作为溶剂，用 Ru 或 Os 钳形配合物和 KOtBu 可在 30-50°C 下高效地使伯醇和仲醇在α位，即与 OH 基团相对的位置上氘代。对于仲醇，也观察到β位的氘原子掺入。在 2-丙醇-d(8)中，钳形配合物催化(S)-1-苯乙醇的同时氘代和外消旋化反应，这两个过程是严格相关的。对于这两种反应，Ru 和 Os 配合物表现出非常相似的活性。与相关的化合物[MCl(2)(NN)(PP)]（NN=双齿胺或吡啶配体）相比，钳形配合物具有更高的活性。新的配合物[MCl(CNN)(PP)]（M=Ru，2、4 和 Os，6、7；PP=dppb，dppf）和[Ru(OTf)(CNN)(dppb)]（3）的合成也有报道。
