Ligand Migrations

Nudear hormone receptor one of a large class of cytoplasmic receptors that, when activated by binding to their ligands, migrate to the nucleus and act as transcription factors. 

Nienhaus, K., Ostermann, A., Nienhaus, U., Parak, R, and Schmidt M. 2005. Ligand migration and protein fluctuations in myoglobin mutant L29W. Biochemistry 44 5095-5105. 

Srajer, V., Ren, Z., Teng, T. Y., Schmidt, M., Ursby, T., Bourgeois, D., Pradervand, C., Schildkamp, W., Wulff, M., and Moffat, K. 2001. Protein conformational relaxation and ligand migration in myoglobin Nanosecond to millisecond molecular movie from time-resolved Laue X-ray diffraction. Biochemistry 40 13802-15. 

Once activated, the substrates are transformed via a number of different possible steps including ligand migration, insertion, elimination or extrusion, and external attack on bound substrate. Of these, the last is most easily envisioned—a reagent not coordinated to the metal center of the catalyst attacks the bound substrate whose coordination has rendered it chemically reactive. 

This reaction might also be imagined to proceed by adsorption of C2H4 followed by ligand migration (an associative surface reaction). 

Fig. 4. Proposed ligand migration process for Ir4(CO), CNBu. Reprinted with permission from Chem. Rev. 78, 642 (1978). Copyright 1978 American Chemical Society.

It should be noted that the carbene ligand migrated from W to a position bridging the Pt—Pt bond during the course of reaction (21). On the basis... 

Pt(/i) remains intact between successive propagation steps, i.e. there is no ligand migration or rotation about the Mt=C bond) [121] ... 

Oxidative insertion, reductive i, and ligand migration from... 

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