Versatility of Iminophosphoranes and Noninnocent Behavior of the 1,5-Cyclooctadiene Ligand in Palladium(II) Complexes. Synthesis of -Allyl Derivatives

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• 作者：David Aguilar ; Francisco Azná ; rez ; Raquel Bielsa ; Larry R. Falvello ; Rafael Navarro ; Esteban P. Urriolabeitia
• 刊名：Organometallics
• 出版年：2007
• 出版时间：December 3, 2007
• 年：2007
• 卷：26
• 期：25
• 页码：6397 - 6402
• 全文大小：126K
• 年卷期：v.26,no.25(December 3, 2007)
• ISSN：1520-6041

文摘

The treatment of PdCl₂(NCPh)₂ with Ph₃P=NPh (1) gives the expected complex trans-PdCl₂[N(Ph)PPh₃]₂ (3). However, the reaction of PdCl₂(COD) (COD = 1,5-cyclooctadiene) with 1 or Ph₃P=N-1-Np(2) (Np = naphthyl) occurs through nucleophilic attack of 1 or 2 on one olefinic bond of the COD ligandfollowed by proton abstraction on the adjacent methylene group, giving the ¹-allyl complexes[Ph₃P(R)NH···Cl₂Pd(C₈H₁₁)] (R = Ph, 4; Np, 5). The X-ray structure of 4 has been determined andshows two interesting facts: (i) the ¹-²-bonded cyclooctadienyl ligand, containing a ¹-allyl fragment,and (ii) the presence of a strong H bond between one of the Cl ligands and the proton of the NH group.This H bond persists in solution, as shown by NMR and molar conductance measurements. The abstractionof a chloride on 4 by reaction with AgClO₄ cleaves the H bond and gives a mixture of the salt [Ph₃PN(H)Ph](ClO₄) (6) and the neutral ¹-²-cyclooctadienyl complex [Pd(-Cl)(C₈H₁₁)]₂ (7). Complex 7 isan adequate precursor for the synthesis of other stable ¹-allyl complexes, and no ¹-³ allylinterconversion has been observed.