[Ni{N(SiMe2CH2PtBu2)2}]+: Direct Observation of Transannular SiC(sp3) Bond Coordination

Fan, Hongjun; Fullmer, Benjamin C.; Pink, Maren; Caulton, Kenneth G.

doi:10.1002/ange.200802654

Cited by 11 publications

(2 citation statements)

References 37 publications

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“…Under similar conditions, no chemical exchange between the magnetically non‐equivalent phosphorus environments in 4 was observed. The interconversion of 6 and 7 (possibly via the intermediate 5‐Ni or a related σ complex,13 Scheme ) was further confirmed by 1 H– 1 H EXSY NMR spectroscopy experiments (70 °C; mixing times=0.75 and 1.5 s), which revealed chemical exchange between the SiMe and NiMe environments in 6 and 7 14. Given the rarity of well‐documented SiC(sp 3 ) bond activation processes that involve first‐row transition metals,10b, 15 the facile and reversible nickel‐mediated SiC(sp 3 ) bond cleavage reaction required for the interconversion of 6 and 7 is remarkable, especially in light of the robust nature of the SiC(sp 3 ) linkage (bond dissociation energy of ca.…”

Section: Methodsmentioning

confidence: 99%

Dynamic Mixtures: Challenges and Opportunities for the Amplification and Sensing of Scents

Herrmann

2012

Chemistry A European J

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Nature generates compounds as complicated mixtures, but surprisingly little is known about the synergies or inhibitory effects of compound mixtures, which is likely to become an important research area in life sciences in the near future. Some recently developed concepts in dynamic combinatorial/covalent chemistry (DCC) have been applied to amplify (increase the intensity and long-lastingness of perception) and sense (selectively detect and discriminate) individual bioactive volatile molecules in compound mixtures. This Concept article focuses on the potential of DCC to impact and modulate the biological and chemical properties of mixtures of bioactive volatile compounds to gain a more fundamental understanding of the properties of compound mixtures in molecular recognition.

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Section: Methodsmentioning

confidence: 99%

Dynamic Mixtures: Challenges and Opportunities for the Amplification and Sensing of Scents

Herrmann

2012

Chemistry A European J

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“…The 31 P NMR spectrum of intermediate B consists of doublets at δ=103 and 55 ppm ( 2 J P–P =21 Hz), suggesting that there are two phosphine groups on the same palladium in a non‐ trans configuration 35. The chemical shift of metal‐bound phosphine groups strongly correlates with metal‐phosphorus‐R group angles 36.…”

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Oxygen‐Promoted CH Bond Activation at Palladium

et al. 2014

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[Pd(P(Ar)(tBu)2)2] (1, Ar=naphthyl) reacts with molecular oxygen to form Pd(II) hydroxide dimers in which the naphthyl ring is cyclometalated and one equivalent of phosphine per palladium atom is released. This reaction involves the cleavage of both C-H and O-O bonds, two transformations central to catalytic aerobic oxidizations of hydrocarbons. Observations at low temperature suggest the initial formation of a superoxo complex, which then generates a peroxo complex prior to the C-H activation step. A transition state for energetically viable C-H activation across a Pd-peroxo bond was located computationally.

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Nickel and Palladium Silyl Pincer Complexes: Unusual Structural Rearrangements that Involve Reversible SiC(sp³) and SiC(sp²) Bond Activation

2009

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Transition-metal pincer complexes have been the subject of numerous reactivity studies that range from explorations of catalytic activity to investigations of challenging bond-activation reactions. [1] With the goal of extending the versatility of metal pincer chemistry, significant effort has been devoted to the development of new pincer-like tridentate ligands by variation of the steric and electronic properties of the donor fragments and/or the ligand backbone. [1,2] In this context, pincer ligands that feature a bis(o-phenylene) backbone have emerged as particularly attractive candidates for the synthesis of highly reactive early-and late-transition-metal complexes. [3][4][5][6] Such o-phenylene linkers provide a relatively rigid ligand architecture, and the lack of b-hydrogen atoms in the resulting complexes circumvents potential ligand degradation by b-hydride elimination. A variety of such phenylene-bridged pincer ligands have been reported, including examples where the central donor is an amido, [1a, 3] phosphido, [4] carbene, [5] or silyl group. [6,7] In this regard, we have recently introduced silyl pincers of the type [k 3 -(2-R' 2 PC 6 H 4 ) 2 SiMe] À ((R'ÀPSiP), R' = Ph, cyclohexyl (Cy)); [6a-c] we considered that the strongly electron-donating and translabilizing central Si donor may promote the formation of electron-rich and coordinatively unsaturated complexes that exhibit aggressive reactivity with s bonds. Indeed, we have demonstrated that [(Cy À PSiP)Ir] species undergo facile arene CÀH bond-activation chemistry. [6b] We have recently begun to investigate Group 10 metal (R'-PSiP) complexes and have reported the synthesis of [(R'À PSiP)Pt II ] species, including examples of square-planar complexes that feature alkyl, aryl, or silyl substitution trans to the pincer Si donor. [6c] In expanding this chemistry to Ni and Pd, we uncovered an unusual ligand rearrangement for [(Cy À PSiPM)(alkyl)] species (M = Ni, Pd) that involves remarkably facile SiÀC(sp 3 ) and SiÀC(sp 2 ) bond-cleavage processes; these results are reported herein. Notably, for M = Ni, these SiÀC bond-activation processes are reversible on the timescale of NMR spectroscopy in solution. Although SiÀC(sp 2 ) bond activation is well-documented, [8] examples of unstrained SiÀ C(sp 3 ) bond cleavage within the coordination sphere of a mononuclear metal complex are extremely rare, [9,10] and are unprecedented for Ni. [11] By comparison, this ligand rearrangement was not observed in our previously reported [(R'À PSiP)Pt II ] chemistry. [6c] In the pursuit of new Ni and Pd alkyl complexes, the [(CyÀ PSiP)MCl] species (M = Ni, 1; M = Pd, 2) were treated with alkyl lithium and Grignard reagents. In the case of 2, treatment with 1 equivalent of MeLi led to the formation of [(Cy À PSiP)PdMe] (3), which was isolated in 78 % yield (Scheme 1). [12] The NMR spectra of isolated 3 (in [D 6 ]benzene) are consistent with a C S -symmetric complex, as indicated by the presence of a single resonance in the 31 P NMR spectrum at d = 60.5 ppm. The ...

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[Ni{N(SiMe₂CH₂PtBu₂)₂}]⁺: Direct Observation of Transannular SiC(sp³) Bond Coordination

Cited by 11 publications

References 37 publications

Dynamic Mixtures: Challenges and Opportunities for the Amplification and Sensing of Scents

Dynamic Mixtures: Challenges and Opportunities for the Amplification and Sensing of Scents

Oxygen‐Promoted CH Bond Activation at Palladium

Nickel and Palladium Silyl Pincer Complexes: Unusual Structural Rearrangements that Involve Reversible SiC(sp³) and SiC(sp²) Bond Activation

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[Ni{N(SiMe2CH2PtBu2)2}]+: Direct Observation of Transannular SiC(sp3) Bond Coordination

Cited by 11 publications

References 37 publications

Dynamic Mixtures: Challenges and Opportunities for the Amplification and Sensing of Scents

Dynamic Mixtures: Challenges and Opportunities for the Amplification and Sensing of Scents

Oxygen‐Promoted CH Bond Activation at Palladium

Nickel and Palladium Silyl Pincer Complexes: Unusual Structural Rearrangements that Involve Reversible SiC(sp3) and SiC(sp2) Bond Activation

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[Ni{N(SiMe₂CH₂PtBu₂)₂}]⁺: Direct Observation of Transannular SiC(sp³) Bond Coordination

Nickel and Palladium Silyl Pincer Complexes: Unusual Structural Rearrangements that Involve Reversible SiC(sp³) and SiC(sp²) Bond Activation