34431-14-6Relevant articles and documents
Kinetic-Mechanistic and Solid-State Study of the Oxidative Addition and Migratory Insertion of Iodomethane to [Rhodium(S,O-BdiPT or N,O-ox)(CO)(PR1R2R3)] Complexes
Warsink, Stefan,Riekert Kotze,Janse van Rensburg, J. M. (Inus),Venter, Johan A.,Otto, Stefanus,Botha, Ebrahiem,Roodt, Andreas
, p. 3615 - 3625 (2018/09/11)
Rhodium(I) carbonyl complexes containing bidentate X,O-Bid [S,O-BdiPT or N,O-ox; S,O-BdiPTH = N-benzoyl-N′,N′-(diphenyl)thiourea; N,O-oxH = 8-hydroxyquinoline] ligands of the form [Rh(X,O-Bid)(CO)(PR1R2R3)] (R1, R2, R3 = Ph or Cy) bearing different phosphine ligands, were investigated, the structural characterization of four example complexes is described and an extensive spectroscopic kinetic-mechanistic study of the oxidative addition of iodomethane thereto is discussed. Reaction with iodomethane led to RhIII-acyl species as secondary (final) products, whereas the primary RhIII-alkyl complexes, although rapidly formed, were only observed as intermediates, in small quantities for S,O-BdiPT (large S–Rh–O bite angle of 90–91°) but in significant amounts for N,O-ox complexes (less steric with a smaller N–Rh–O bite angle of 79–80°). Overall, almost an order-of-magnitude difference in rate constants was observed for the S,O-BdiPT complexes, with the PPh2Cy- and PPhCy2-bearing complexes showing the largest variation. In both the S,O-BdiPT and N,O-ox ligand systems an associative activation is inferred from the large negative ΔS≠ values. The relative reactivity of RhI-X,O-Bid complexes, where X = O, S or N, follows a surprising similar reactivity relationship when stepwise varying the PPh3, PPh2Cy, PPhCy2 and PCy3 tertiary phosphine ligands, suggesting a systematic behavior by the PR3 ligands, independent of the X,O-Bid ligand at the RhI metal center.
CYCLOMETALLATION REACTIONS IN COMPLEXES OF THE TYPE Rh(oq)(CO). THE MOLECULAR STRUCTURE OF (oq = 8-hydroxyquinolinate)
Barcelo, F. L.,Besteiro, J. C.,Lahuerta, P.,Foces-Foces, C.,Cano, F. H.,Martinez-Ripoll, M.
, p. 343 - 352 (2007/10/02)
Cyclometallation occurs when a solution of the complex Rh(oq)(CO)(PCBr), (PCBr = 2-bromo-3,4,5,6-tetraffluorophenyldiphenylphosphine; oq = 8-hydroxyquinolinate) in toluene is refluxed, giving (PC = P(C6F4)(C6H5)2) and a dimeric compound, not yet completely characterized, formulated as Rh2Br(oq)(PCBr)2. was characterized by elemental analysis, by conductance measurements, and by 19F, 31P NMR and infrared spectroscopy.Its molecular structure was determined by single-crystal X-ray methods and refined by standard procedures to final agreement factors R and Rw of 0.067 and 0.060 for 5346 observed data.Lattice constants are 15.8494(6), 14.7188(5), 14.6675(5) Angstroem and β 96.933(3) deg, with monoclinic symmetry.The complex has a distorted octahedral geometry with a four atom metallocycle-ring (Rh-P-C-C) showing distorted angles of 69.8(2) and 84.8(2) deg at Rh and P atoms, respectively.The analogous compound , (5-moq = 5-methyl-8-hydroxyquinolinate), can be obtained by heating Rh(5-moq)(CO)(PCBr).
