212962-75-9Relevant academic research and scientific papers
Electronic Effect of Substituents on Cyclopalladation of the Solvated Palladium(II) Complexes with N-Benzyl Triamine [Pd(Sol){(4-XC6H4CH2)NH(CH2) 3NR(CH2)3NH2}]2+ (Sol = Solvent; R = Ph, H, and Me; X = H, Et, Me, MeO, Cl, and NO2)
Yagyu, Takeyoshi,Iwatsuki, Satoshi,Aizawa, Sen-Ichi,Funahashi, Shigenobu
, p. 1857 - 1862 (1998)
The solvated palladium(II) complexes with the potentially cyclopalladating monobenzyl triamine ligand, [Pd(CH3CN)(BnPhdptn)](BF4) 2(1)(BnPhdptn=N-(3-aminopropyl)-N' -benzyl- 1,3-propanediamine), [Pd(CH3CN)(4-XC6H4CH2dptn)](BF 4)2 (4-XC6H4CH2dptn = N-(3-aminopropyl)-N'-(4-substituted benzyl)-1,3-propanediamine; X = Me (3), MeO (4), Cl (5), and NO2 (6)), and [Pd(CH3CN)(4-XC6H4CH 2Medptn)](BF4)2 (4-XC6H4CH2Medptn = N-(3-aminopropyl)-N'-(4substituted benzyl)-methyl-1,3-propanediamine; X = Et (8), Me (9), MeO (10), Cl (11), and NO2 (12)) have been synthesized. The kinetics for the cyclopalladation of 1-6, [Pd(CH3CN)(BnMedptn)](BF4)2 (7) (BnMedptn = N-(3-aminopropyl)-N'-benzyl-N-methyl- 1,3-propanediamine), 8-12 in N,N-dimethylformamide (DMF), and 7,9,11, and 12 at 25 °C in dimethyl sulfoxide (DMSO) have been investigated. The Hammett p values for the rate constants at 25 °C obtained by variation of the 4-substituent on the benzyl group were -0.73 for 2 - 6 and -0.87 for 7 - 12 in DMF, and -0.67 for 7, 9, 11, and 12 in DMSO using the substituent constants for the meta position, σm. The difference in the rate constants for 1, 2, and 7 at 25 °C in DMF and the negative p values confirmed that the present cyclopalladation proceeds by the electrophilic attack of the palladium(II) center on the ortho benzyl carbon. We have also discussed the electronic effects of the solvent and the N-substituent of the bound triamine on the p values to arrive at a conclusion for the reaction mechanism of [Pd(solvent)(N-benzyltriamine)]-type complexes.
