Mechanistic studies on the alcoholysis and aminolysis of [(MeZn)(2){mu-N(H)tBu}{mu-N(CH2Py)(2)}]

作者：Kahnes Marcel; Richthof Julia; Goerls Helmar; Escudero Daniel; Gonzalez Leticia^*; Westerhausen Matthias

来源：Journal of Organometallic Chemistry, 2010, 695(2): 280-290.

DOI：10.1016/j.jorganchem.2009.09.041

• Alkylzinc compounds
• mu-OMc, mu-N(H)R functionalities
• Three-centered X-H-Y bonds
• Mechanistic studies
• DFT calculations

The reaction of bis(2-pyridylmethyl)amine (II) with t-butylamine and dimethylzinc gives the heteroleptic [(MeZn)(2){mu-N(H)tBu}{mu-N(CH2Py)(2)}] (1). Stoichiometric alcoholysis of 1 with methanol leads to the exchange of the mu-N(H)tBu moiety. Almost quantitatively the corresponding methoxide [(MeZn)(2)(mu-OMe){mu-N(CH2Py)(2)}] (2) is formed. Alternatively bis(alkylzinc)methoxide-bis(2-pyridylmethyl)amides (Alkyl = methyl (2), bis(trimethylsilyl)methyl) (3)) are also accessible by direct zincation of bis(2-pyridylmethyl)amine (II) and methanol with dialkylzinc regardless of the bulkiness of the alkyl groups. Extensive DFT calculations on the alcoholysis mechanism reveal the preferential insertion of methanol into a zinc amide bond rather than the cleavage of zinc carbon bonds. An intermediate with a Zn[mu-MeO center dot center dot center dot H center dot center dot center dot NHR)]Zn functionality is predicted. Aminolyis of 1 with t-butylamine leads to intermediates with Zn[mu-(RNH center dot center dot center dot H center dot center dot center dot NHR)]Zn functionalities, respectively. We were able to detect the latter by H-1 NMR spectroscopy. The aminolysis of 1 with an excess of phenylamine results in a partial decomposition of the complex leading to the hexanuclear amide [{Zn(mu-N(H) Ph)}{MeZn(mu-N(H)Ph)}(2){mu-N(CH2Py)(2)}](2) (4). Compound 2 is able to cleave silicon grease when dissolved in t-butylamine yielding [(MeZn)(2){mu-N(CH2Py)(2)}(2)Zn{mu-(OMe2Si)(2)O}] (5). The X-ray structures of complexes 1-5 are discussed.

• 出版日期2010-1-15