Ligand Scrambling

Exchange piUhways A. metal localized ligand scrambling B. 

Because all of the ligands are leaving one metal ion and attaching to another, this type of reaction is sometimes known as ligand scrambling. 

OSN responses to peptides were found to be highly sensitive, with thresholds down to 10 11M, although they were around two orders of magnitude less sensitive than VSN responses (Spehr et al. 2006). OSN responses to MHC peptide ligands also displayed a different dependence on anchor residues. Whereas replacement of anchor residues with alanines abolished the responses of VSNs, it shifted the stimulus response curve of around two thirds of the OSNs, making them less sensitive by approximately two orders of magnitude. However, OSNs still failed to respond to the scrambled version of the peptide or a mixture of its constituent amino acids (Spehr... 

Fig. 8 Proposed mechanisms for scrambling the two carbons of the ethyl ligand (a) for making equivalent the two P atoms (b). Adapted from [115]...

Flash vapor pyrolysis of the rf -thiophene l,l-dioxide)cobalt complexes results in extrusion of SO2 to generate (cyclobutadiene)cobalt complexes (Scheme 63)229. The absence of ligand crossover products indicates that this reaction occurs in a unimolecular fashion. Pyrolysis of the diastereomerically pure complex 240 gave the cyclobutadiene complex as an equimolar mixture of diastereomers 241a and 241b. In addition, the recovered starting material (37%) was shown to have ca 40% scramble of the diastereomeric... 

These two experiments indicate that extensive scrambling of hydrogen between the hydride and PMe2Ph ligands occurs upon... 

Adams, R.D., Brice, M. and Cotton, F.A. (1973) Intramolecular ligand scrambling via bridged transition states or intermediates in di(pentahapto-cyclopentadienyl) (methyl isocyanide) (pentacarbonyl)dimolybdenum. J. Am. Chem. Soc., 95, 6594-502. 

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