C鈥揌 Bond Activation by a Palladium(II) Thioether Complex: Formation of the Bis(nitromethanate) Complex [Pd(9S3)(CH2NO2)2]

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• 作者：John P. Lee ; C. Luke Keller ; Ashley A. Werlein ; Daron E. Janzen ; Donald G. VanDerveer ; Gregory J. Grant
• 刊名：Organometallics
• 出版年：2012
• 出版时间：September 24, 2012
• 年：2012
• 卷：31
• 期：18
• 页码：6505-6513
• 全文大小：330K
• 年卷期：v.31,no.18(September 24, 2012)
• ISSN：1520-6041

文摘

Palladium(II) acetate reacts with 1 equiv of 1,4,7-trithiacyclononane (9S3) at room temperature to produce the neutral complex [Pd(9S3)(OAc)₂] (1; OAc^{鈥?/sup> = CH₃COO鈥?/sup>) as an analytically pure yellow solid, which has been characterized using 1H and 13C NMR spectroscopy and single-crystal X-ray diffraction. The crystal structure of 1 shows the first example of an exodentate third sulfur of the 9S3 ligand in a Pd(II) complex. Complex 1 reacts with nitromethane at room temperature in methanol to produce [Pd(9S3)(CH₂NO₂)₂] (2) and acetic acid, as confirmed by 1H NMR and 13C NMR spectroscopy. Moreover, complex 2 has been characterized by single-crystal X-ray diffraction. Its crystal structure is the first example of any transition-metal complex containing two nitromethanate (anionic nitromethane) ligands. The complex shows the more typical elongated-square-pyramidal structure and [S₂C₂ + S₁] coordination with one long Pd鈥揝 axial interaction at 2.823(2) 脜 and two C-bound nitromethanate ligands. Interestingly, each nitromethanate ligand is in a different coordination environment and varies in their trans-directing abilities. Reactivity studies suggest that the complexation behavior of the 9S3 ligand and the Pd(II) center as well as the 蟽-donor ability of the leaving group play key roles in the C鈥揌 activation of the nitromethane. Two related metal complexes, [Pd(dppe)(OAc)₂] (dppe = 1,2-bis(diphenylphosphino)ethane) and [Pd(9S3)(CF₃COO)₂], were synthesized, but neither of these react in a similar fashion to form a nitromethanate complex. Also, the reaction of 1 with nitrobenzene and nitrocyclopentane was studied, but these nitro-organics do not undergo C鈥揌 bond activation like nitromethane.}