Axial-equatorial ligand exchange

Axial-Equatorial Ligand Exchange. In addition to the above described very fast, dynamic puckering of the pentagon equatorial fluorine plane which requires... 

The turnstyle mechanism is another possible way of an intramolecular ligand exchange. In the process of a turnstyle motion one of the axial ligands and one of the equatorial ligands exchange their places as if rotation about the local axis were of second order, the remaining three atoms rotating about the third order axis in the opposite direction... 

Tris(amido)phosphines 40-43 react with Fc2(CO)9 to give mononuclear iron carbonyl complexes Fe(CO)4(PR3). IR data collected from these complexes, combined with data from similar complexes, revealed the TT-acidity of the phosphines to be 41 w 40 > 43 > P(OPh>3 >42 > PPh3 > P(NMe2)3- Variable-temperature NMR on the Fe(GO)4 complexes of 41-43 showed rapid exchange of axial and equatorial carbonyls from —80 to 20 °C, while complex 40 showed slow axial-equatorial carbonyl exchange even at room temperature, attributed to the steric bulk and rigidity of the ligand. 

The relationship between metal carbonyl hydrides and dihydrogen complexes of metal carbonyl derivatives has been further explored.The interactions of d ML5 fragments with H2 have been studied by EHMO methods,and the structures and some reactions of n -H2 complexes of Cr, Mo, W, Fe and Co carbonyl derivatives examined.Intramolecular ligand rearrangements in [M(C0)5H] anions (M = Cr or Mo) have been investigated using variable temperature n.m.r. A twist mechanism that provides a pathway for intramolecular axial-equatorial CO exchange is favoured.The catalytic role of these... 

Biirgi studied also a series of five coordinated cadmium complexes, 38, that contain three equatorial sulfur ligands, but in which the fourth and fifth, axial ligands, X and Y, are sometimes iodine, sometimes sulfur, and sometimes oxygen (84). The structural correlations have a clear interpretation in terms of the ligand exchange reaction and are reminiscent of the kind of process that is believed to occur in S 2-type nucleophilic substitution reactions ... 

The six water molecules are arranged around Cu(II) ion in a tetragonally distorted octahedron. " Substitution can easily occur at the very labile axial positions. Rapid inversion of the axial and equatorial ligands leads then to apparent easy substitution in the equatorial position. The water exchange is too rapid (k 10 "s- ) to be determined accurately by O nmr. The Cu(II)-methanol system is more amenable to study. The mean lifetime at 25°C of a particular tetragonal distortion in Cu(MeOH) + is 1.2 x 10 " s while that for a... 

Thus, in the reaction of aryllead triacetate with phenols, an initial ligand exchange affords an aryl-(aryloxy)lead diacetate intermediate which can have the aryloxy ligand either in the axial position 51 or in the equatorial position 52 (Scheme 9). If the aryloxy group is in the axial position, pseudorotation can easily interconvert this conformer with... 

Reaction of Os P(OMe)3 2Cl4 and P(OMe)3 with sodium amalgam in THF yields the white Os P(OMe)3 5. Study of the 31P[ H] NMR spectra showed simultaneous slow exchange of axial and equatorial ligands consistent with a Berry mechanism.429... 

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