Nickel(II) and Palladium(II) Complexes of the Small-Bite-Angle P-Stereogenic Diphosphine Ligand MaxPHOS and Its Monosulfide

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• 作者：Arnald Grabulosa ; Séan Doran ; Guillem Brandariz ; Guillermo Muller ; Jordi Benet-Buchholz ; Antoni Riera ; Xavier Verdaguer
• 刊名：Organometallics
• 出版年：2014
• 出版时间：February 10, 2014
• 年：2014
• 卷：33
• 期：3
• 页码：692-701
• 全文大小：465K
• ISSN：1520-6041

文摘

Coordination studies of the optically pure diphosphine ligand (t-Bu)₂P(NH)P(t-BuMe) (MaxPHOS) and its monosulfide with several Pd and Ni moieties are described. Treatment of a solution of MaxPHOS路HBF₄ with [M(acac)₂] (M = Ni, Pd) in methanol or dichloromethane cleanly produced [M(MaxPHOS)(acac)]BF₄. Reaction of the same salt with Pd(OAc)₂ in the presence of excess NaBr in methanol produced the corresponding neutral complex [PdBr₂(MaxPHOS)]. The [PdCl₂(MaxPHOS)] complex was prepared by the reaction of free (S)-MaxPHOS with [PdCl₂(cod)]. Reaction of (S)-MaxPHOS路HBF₄ with Pd allylic dimers [PdCl(畏³-R-C₃H₄)]₂ (R = 2-methyl, 1-phenyl, 1,3-diphenyl) in the presence of excess Na₂CO₃ and NH₄BF₄ in dichloromethane produced the cationic complexes [Pd(MaxPHOS)(畏³-R-allyl)]BF₄ in good yields. Reaction of MaxPHOS monosulfide with [Pd(acac)₂] produced the neutral complex [Pd(MaxPHOS路S)₂], where both ligands are anionic. Protonation of this complex generated [Pd(MaxPHOS路S)₂]BF₄, a complex formally bearing an anionic and a neutral ligand. Full characterization, including five crystal structure determinations, for all of the complexes is provided. Preliminary catalytic studies of the performance of the Pd allylic complex [Pd(MaxPHOS)(畏³-2-Me-allyl)]BF₄ in allylic substitution reactions are also presented.