1887

n Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie - Waargenome struktuur- en reaktiwiteitsverwantskappe in trans-[PtPh(L)2Cl] tydens die verplasingreaksie van Cl- deur I- na verandering van die fosfien-, arsien- en stibienligande (L) - oorspronklike navorsing

Volume 38 Number 1
  • ISSN : 0254-3486
  • E-ISSN: 2222-4173

Abstract

Vierkantig-planêre chloried vir jodied stubstitusiereaksies trans ten opsigte van ‘n feniel σ-C binding is kineties ondersoek in chloroform vir ‘n reeks steries-gestremde platinum(II) komplekse van die vorm trans-[PtPh(L)2Cl] (L = PPh3, 1; PPh2Fc, 2; AsPh3, 3; SbPh3, 4). Die reaksies volg die normale assosiative aktivering, maar met ewewigte teenwoordig in alle stappe. Die tempokonstantes vir die direkte roete k12, is onderskeidelik (0.37 ± 0.03)×10-3 en 0 M-1 s-1 vir 1 en 2 by 40°C, en (1.6 ± 0.3)×10-3 en (143 ± 10)×10-3 M-1 s-1 vir 3 en 4 by 25°C. Die ooreenstemmende tempokonstantes vir die oplosmiddelroete, k13, is onderskeidelik (0.66 ± 0.03)×10-4 en (2.0 ± 0.2)×10-4 s-1 vir 1 en 2 by 40°C en (4.1 ± 0.6)×10-4 en (1105 ± 14)×10-4 s-1 vir 3 en 4 by 25°C. Die aktiveringsparameters vir 3 en 4 is bepaal as ΔH≠ = 99.8 ± 0.6 en 31 ± 1 kJ mol-1, met ∆S≠= 36 ± 2 en -157 ± 4 J K-1 mol-1 vir die direkte roete, k12, en ΔH≠ = 45 ± 2 en 22.91 ± 0.11 kJ mol-1 en ∆S≠= -181 ± 7 en -207.3 ± 0.4 J mol-1 K-1 vir
die oplosmiddelroete, k13 onderskeidelik. Die kristalstrukture van trans-[PtPh(PPh2Fc)2Cl], trans-[PtPh(AsPh3)2Cl], trans-[PtPh(SbPh3)2Cl] en trans-[PtPh(SbPh3)2I] word gerapporteer. Struktuur- en reaktiwiteitsverwantskappe (van ongeveer vier ordegroottes) word bespreek, gebaseer op kinetiese data, multikern KMR-metings en die kristallografiese data.

Structure and reactivity relationships in trans-[PtPh(L)2Cl] as observed from Cl- anation by I- upon interchanging phosphine, arsine and stibine (L) ligands: Square-planar chloride for iodide substitution reactions trans to a phenyl σ-C was kinetically investigated in a series of sterically congested platinum(II) complexes of the form trans-[PtPh(L)2Cl] (L = PPh3, 1; PPh2Fc, 2; AsPh3, 3; SbPh3, 4) in chloroform solution. The reactions follow the normal associative mode of activation, but with equilibria present in all steps. The rate constants for the direct pathway, k12, are (0.37 ± 0.03)×10-3 and 0 M-1 s-1 for 1 and 2 at 40 °C, and (1.6 ± 0.3)×10-3 and (143 ± 10)×10-3 M-1 s-1 for 3 and 4 at 25 °C. The corresponding rate constants for the solvent assisted pathway, k13, are (0.66 ± 0.03)×10-4 and (2.0 ± 0.2)×10-4 s-1 for 1 and 2 at 40 °C and (4.1 ± 0.6)×10-4 and (1105 ± 14)×10-4 s-1 for 3 and 4 at 25 °C. The activation parameters for 3 and 4 were determined as ΔH≠ = 99.8 ± 0.6 and 31 ± 1 kJ mol-1 and ∆S≠= 36 ± 2 and -157 ± 4 J K-1 mol-1 for the direct route, k12, and ΔH≠ = 45 ± 2 and 22.91 ± 0.11 kJ mol-1 and ∆S≠= -181 ± 7 and -207.3 ± 0.4 J mol-1 K-1 for the solvent assisted, k13, pathways respectively. The crystal structures of trans-[PtPh(PPh2Fc)2Cl], trans-[PtPh(AsPh3)2Cl], trans-[PtPh(SbPh3)2Cl] and trans-[PtPh(SbPh3)2I] are reported. Structure and reactivity relationships (of almost four orders-of-magnitude) are presented based on kinetic data, multi-nuclear NMR measurements and the crystallographic data.

Loading full text...

Full text loading...

Loading

Article metrics loading...

/content/journal/10520/EJC-1c96431636
2020-04-22
2020-07-05

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error