Dynamic behaviour of carbon-metallated palladium hydrazone complexes. Crystal structures of [{Pd[CH2CMe2C(N–NMePh)Me]Cl}2] and [{Pd[CH2C(N–NMePh)But]Cl}2]

Galli, Beatrice; Gasparrini, Francesco; Mann, Brian E.; Maresca, Luciana; Natile, Giovanni; Manotti-Lanfredi, Anna M.; Tiripicchio, António

doi:10.1039/dt9850001155

Cited by 22 publications

(9 citation statements)

References 7 publications

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“…A case of preference of C(sp 3 )−H bond activation over the C(sp 2 )−H bond was reported for N -phenyl N -methyl hydrazone of 3,3-dimethyl-2-butanone. The observed C(sp 2 )−Pd bond formation and regiospecific palladation of the tert -butyl group are quite unique, because metalation of the N,N -dimethyl hydrazone of the same ketone exclusively furnished a palladacycle containing an C(sp 3 )−Pd bond. , The preference of the benzylic C(sp 3 )−H bond activation to form a six-membered palladacycle over C(sp 2 )−H activation leading to exo isomers was shown by Albert et al in studying reactions of 2,4,6-(CH 3 ) 3 C 6 H 2 CHN(CH 2 ) n C 6 H 5 ( n = 0−2) with Pd(OAc) 2 in AcOH …”

Section: Resultsmentioning

confidence: 93%

Endo-Effect-Driven Regioselectivity in the Cyclopalladation of (S)-2-tert-Butyl-4-phenyl-2-oxazoline

et al. 2007

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Direct cyclopalladation of (S)-2-tert-butyl-4-phenyl-2-oxazoline using palladium acetate in acetic acid or acetonitrile provided a mixture of two isomeric compounds, the endo μ-AcO dimeric complex with a C(sp3)−Pd bond and the corresponding exo derivative with a C(sp2)−Pd bond, with the former being the major product. The μ-AcO dimeric complexes were converted to the corresponding μ-Cl analogues 3 and 4 by treatment with LiCl in acetone; the latter compounds were transformed to the corresponding PPh3 adducts 5 and 6. The NMR data suggested the puckered structure of the endo palladacycle in complexes 3 and 5, the twisted λ(S) conformation of the oxazoline ring in 3, 4, and 6, and the δ(S) conformation of the heterocycle in complex 5. The X-ray crystal structure of 5 confirmed the δ(S) conformation of the oxazoline ring in the solid state and the twisted conformation of the palladacycle and revealed a P-propeller chiral configuration of the PPh3 ligand. A series of ab initio quantum chemical calculations were performed on two model compounds generated by replacing the PPh3 ligands with NH3 in complexes 5 and 6. The structures and energies of the two model exo and endo isomers were calculated at the RHF, BLYP, and MP2 levels of theory with a 6-31G* basis for the light atoms and LANL2DZ ECP for the palladium and were found to be comparable. Single point coupled cluster calculations, with single double excitations (CCSD), corroborated the results.

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Section: Resultsmentioning

confidence: 93%

Endo-Effect-Driven Regioselectivity in the Cyclopalladation of (S)-2-tert-Butyl-4-phenyl-2-oxazoline

et al. 2007

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“…Cyclopalladated ferrocene 231b reacted with I2 to afford the iodoferrocene 241a.133 Complex 231b also reacted with CO in MeOH to afford the ferrocenyl amino ester 241b,133,138 as well as underwent the Heck reaction with a variety of alkenyl reagents to give C-H insertion products (e.g., 241c) in variable yields 133,[138][139][140]158. Replacement of the dimethylamino moiety with a 2-pyridyl group was accomplished, and the resultant complexes have been demonstrated to be…”

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confidence: 99%

Cyclometalation of the platinum metals with nitrogen and alkyl, alkenyl, and benzyl carbon donors

Newkome¹,

Puckett²,

Gupta³

et al. 1986

Chem. Rev.

401

151

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“…10 The distances within the bridging hydrazonides in [ClZn(CH 2 C(Me)dNNMe 2 )(py)] 2 and [Zn(CH 2 C(Me)d NNMe 2 ) 2 ] 2 also constrast with the distances found in three palladacycles incorporating terminal chelating hydrazonide ligands, the only other structurally characterized hydrazonide complexes. [12][13][14] In the palladacycles, the C-CH 2 Pd and C-N imine distances average 1.51 and 1.28 Å, respectively, [12][13][14] indicating localization of the charge on the hydrazonide methylene carbon as described by V. solid state structure, showing singlet resonances in the methylene, methyl, and amine methyl regions with relative intensities 2:9:6, respectively.…”

Section: Synthesis Of Zinc Hydrazonide Complexesmentioning

confidence: 96%

Synthesis of Zinc Hydrazonide Complexes

Javed

Hoffman

2008

Inorg. Chem.

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The zinc hydrazonide complexes [ClZn(CH(2)C(Me)=NNMe(2))(py)](2), [ClZn(CH(2)C(t-Bu)=NNMe(2))](2), [Zn(CH(2)C(Me)=NNMe(2))(2)](2), Zn(CH(2)C(i-Pr)=NNMe(2))(2), and Zn(CH(2)C(t-Bu)=NNMe(2))(2) were synthesized by salt metathesis reactions, and the coordination polymer [EtZn(CH(2)C(Me)=NNMe(2))](n) was obtained from the reaction between excess ZnEt(2) and [Zn(CH(2)C(Me)=NNMe(2))(2)](2). Single crystal X-ray crystallography studies revealed that the hydrazonide ligands were bound to zinc as chelating alkyl ligands. The ligand precursor [Li(CH(2)C(i-Pr)=NNMe(2))(THF)](n) was also structurally characterized. In the anion of [Li(CH(2)C(i-Pr)=NNMe(2))(THF)](n), the hydrazonide ligand in [EtZn(CH(2)C(Me)=NNMe(2))](n), and the bridging hydrazonide ligands in [Zn(CH(2)C(Me)=NNMe(2))(2)](2) and [ClZn(CH(2)C(Me)=NNMe(2))(py)](2), there is evidence for three-center charge delocalization. In solution, the dimer [Zn(CH(2)C(Me)=NNMe(2))(2)](2) is in equilibrium with the monomer Zn(CH(2)C(Me)=NNMe(2))(2). The thermodynamic parameters DeltaH degrees = 55.8(2.9) kJ/mol, DeltaS degrees = 144(2) J/mol K, and DeltaG degrees (298K) = 13(2) kJ/mol for the equilibrium were obtained from a variable temperature (1)H NMR study.

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Dynamic behaviour of carbon-metallated palladium hydrazone complexes. Crystal structures of [{Pd[CH₂CMe₂C(N–NMePh)Me]Cl}₂] and [{Pd[CH₂C(N–NMePh)Bu^t]Cl}₂]

Cited by 22 publications

References 7 publications

Endo-Effect-Driven Regioselectivity in the Cyclopalladation of (S)-2-tert-Butyl-4-phenyl-2-oxazoline

Endo-Effect-Driven Regioselectivity in the Cyclopalladation of (S)-2-tert-Butyl-4-phenyl-2-oxazoline

Cyclometalation of the platinum metals with nitrogen and alkyl, alkenyl, and benzyl carbon donors

Synthesis of Zinc Hydrazonide Complexes

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