Synthesis of Aryl-, Benzoyl-, and Iminobenzoyl-Palladium(II) Complexes Derived from <i>N</i>-Phenyl Formamide. Synthesis of a Homoleptic Ball-Shaped Tetranuclear Palladium Complex

Vicente-Hernandez, Inmaculada; Chicote, Mariá‐Teresa; Vicente, José; Bautista, Delia

doi:10.1021/acs.organomet.6b00122

Cited by 3 publications

(3 citation statements)

References 68 publications

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“…The bend back angles of 140.6(4) Å (C2–C1–S1) and 131.6(4) Å (C1–C2–N1) in H- 1 are substantially decreased to 122.7(3) Å (C2–C1–S1) and 122.0(3) Å (C1–C2–N1), allowing the chelate coordination. The Pd1–N1 bond length of 2.051(3) Å is comparable to Pd-imine bond length recorded in the literature for S 2 N 2 donor sets and distinctively longer than pure Pd amide bonds. − In contrast, the Pd1–S1 distance of 2.348(9) Å falls above the range of 2.232–2.336 Å, which is reviewed for dithiolene Pd(II) complexes . In contrast to the acdt 2– congener [Tp′W(CO) 2 (C 2 S 2 ) 2 Pd], complex 9 does not show any reversible redox chemistry.…”

Section: Protective Group Removalsupporting

confidence: 68%

Pathways to Polynuclear Complexes with α-S,N-Substituted Alkynes as Bridging Ligands

et al. 2019

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Recently, alkyne complexes with terminal thiolate/ amide substitution have been shown to act as S,N-chelate ligands in dinuclear complexes. In this study, the detailed synthesis and reactivity of W(II) alkyne complexes bearing different amino groups in the α-position are reported. The preparative scheme starts with cationic alkyne complexes [Tp′W(CO) 2 -η 2 -C,C′-C 2 Br(SR)]PF 6 {Tp′ = hydridotris(3,5-dimethylpyrazolyl)borate, R = benzyl (Bn), C 2 H 4 SiMe 3 }, which are obtained by applying free bromo alkynes. Subsequent nucleophilic substitution of the bromine substituent led to unsymmetrical substituted alkyne complexes [Tp′W(CO) 2 -η 2 -C,C′-C 2 (SR)(NHBn)]PF 6 with S,N substitution in the α position of the coordinated alkyne. Depending on the base used, deprotonation of the secondary amine resulted in either neutral iminoketenyl complexes [Tp′W(CO) 2 -η 2 -C,C′-C 2 (SR)(NBn)] or a zwitterionic PF 5 adduct. Reductive removal of the benzyl protective group was primarily observed at the imine substituent, causing a side-on/end-on rearrangement to the cyanide substituted carbene complex K[Tp′W(CO) 2 -η 1 -C(CN)(SBn)]. The reversibility of the rearrangement was proven with HBF 4 /Et 2 O, because double protonation led to [Tp′W(CO) 2 -η 2 -C,C′-C 2 (SR)(NH 2 )]BF 4 exhibiting an unprecedented primary amine substitution at the coordinated alkyne. The reaction sequence starting with the thiol SC 2 H 4 SiMe 3 derivative leading to the desired [Tp′W(CO) 2 -η 2 -C,C′-C 2 S(NHBn)] with a terminal S atom as well as the bonding situation in those complexes is discussed based on full spectroscopic characterization including X-ray structure analyses. Finally, a trinuclear complex assembled by homoleptic coordination of Pd(II) by two anionic S,N-chelates [Tp′W(CO) 2 -η 2 -C,C′-C 2 S(NBn)] − is presented.

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Section: Protective Group Removalsupporting

confidence: 68%

Pathways to Polynuclear Complexes with α-S,N-Substituted Alkynes as Bridging Ligands

et al. 2019

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“…The assignment of 6 as a Pd−iminoacyl complex suggested that the silyl group should be in close proximity to the iminoacyl −CH 3 group in the less sterically encumbered E configuration of the imino group. 85,87,88 Irradiation of the −SiMe 2 Et protons in a 1-D NOESY experiment provided an 8% NOE enhancement of the −CH 3 proton signal, confirming that 6 cannot be the nitrilebound silylpalladium cation (the two groups would be trans) and further supporting the structural assignment as (PCy 3 ) 2 Pd-{C(NSiMe 2 Et)Me} + (see Figure S4 in the Supporting Information).…”

Section: ■ Results and Discussionmentioning

confidence: 54%

“…Key to differentiating between the trans -(MeCN)(PCy 3 ) 2 PdSiR 3 + and (PCy 3 ) 2 Pd{C(NSiR 3 )Me} + structures was the 1 H, 13 C-HMBC experiment, which showed the methyl carbon correlating to a weak quaternary carbon resonance at 176.6 ppm. This chemical shift is not in the region expected for the cyano carbon of ligated acetonitrile but is in the chemical shift range expected for a palladium-bound iminoacyl carbon atom. − The spectroscopic data are thus inconsistent with either a nitrile-ligated silylpalladium cation or a methylpalladium complex, but they are consistent with 6 being a palladium–( N -silyl)iminoacyl cation.…”

Section: Resultsmentioning

confidence: 88%

Silylpalladium Cations Enable the Cleavage of Nitrile C–CN Bonds

et al. 2020

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The stoichiometric addition of aryl and alkyl nitriles to the silylpalladium cation [(PCy 3 ) 2 Pd−SiMe 2 Et + ][(C 6 F 5 ) 4 B − ] (1) resulted in the cleavage of the nitrile C−CN bond and the formation of palladium−aryl and palladium−alkyl cations. Low-temperature experiments support a mechanism where silylpalladium cation 1 transfers silylium to nitrile, generating a silylnitrilium cation and the reduced, zerovalent complex Pd(PCy 3 ) 2 . These two intermediates readily recombine at low temperatures to generate palladium−(N-silyl)iminoacyl complexes, which upon warming can undergo aryl/alkyl group migration from the iminoacyl ligand to the metal. Additional experiments show that palladium−(N-silyl)iminoacyl cations are potent sources of silylium, capable of cleaving the methyl C−O bond of an ether, while DFT calculations confirm the electrophilicity of the silyl moiety.

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Synthesis and Reactivity of Model Intermediates Proposed for the Pd-Catalyzed Remote C–H Functionalization of N-(2-Haloaryl)acrylamides

et al. 2017

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We have studied the possible reaction pathways operating in the Pd-catalyzed remote C−H functionalization of N-(2-haloaryl)acrylamides from an organometallic approach. We have isolated and characterized several proposed reaction intermediates, such as σ-alkyl-Pd complexes and spiro C,Cpalladacycles, and evaluated the role of the base and the auxiliary ligands coordinated to Pd in the remote C−H activation process. In addition, the reactivity of these intermediates toward different unsaturated species such as benzyne, alkynes, and isocyanides has been studied in order to gain further insight into the reaction mechanism leading to functionalized spiro-oxoindoles.

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Synthesis of Aryl-, Benzoyl-, and Iminobenzoyl-Palladium(II) Complexes Derived from N-Phenyl Formamide. Synthesis of a Homoleptic Ball-Shaped Tetranuclear Palladium Complex

Cited by 3 publications

References 68 publications

Pathways to Polynuclear Complexes with α-S,N-Substituted Alkynes as Bridging Ligands

Pathways to Polynuclear Complexes with α-S,N-Substituted Alkynes as Bridging Ligands

Silylpalladium Cations Enable the Cleavage of Nitrile C–CN Bonds

Synthesis and Reactivity of Model Intermediates Proposed for the Pd-Catalyzed Remote C–H Functionalization of N-(2-Haloaryl)acrylamides

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