Pyrrolyl ligand

Carbonylation of azaferrocene includes a rr a rearrangement of the pyrrolyl ligand and is reversible (82IC868). The similar process under the influence of the other TT-acidic ligands [PE3, R2NPE2 (R = Me, Et), MeN(PE2)2, r-BuNC, n-PrNC, Mc2N(CH2)2NC, and PhNC)] occurs. Derivatives based on 29 are isolated. 

The pyrrolyl ligand is interesting in that it can function as both a u-bonded amido group or a yr-bonded multihapto ligand. The pyrrolyl group appears to be a weaker electron donor than the cyclopentadienide anion 90). In the tetrakis-(2,5-dimethylp3u rolyl)uranium(IV) complex a preliminary structure has been revised with a tris(monohapto) (pentahapto) structure now assigned from variable temperature PMR spectra 90). 

Iminophosphoranes, mercuration, 2, 432 (Iminophosphoranyl)ferrocenes, synthesis, 6, 202 Imino-pyrrolate systems, with zirconium, 4, 1138-1139 Imino-pyrrolides, with Zr(IV) and Hf(IV), 4, 780 Imino-pyrrolyl ligands, in chromium complexes, 5, 355 Iminosilanes, reactions, 3, 440 Imprinted complexes, on oxide surface, 12, 810 Impurities, glovebox techniques, 1, 215 Inclusion chemistry... 

The effect of the pyrrolyl ligand may be due to a type of hemilability (see Box 8) arising from an to t coordination shift, the former facilitating metallacycle formation and the latter favouring further ethylene insertion and formation of the chromium-bonded 5-hexenyl species. 

Samarium chemistry with polydentate pyrrolyl ligands is also very diverse. Divalent and trivalent dinuclear samarium complexes supported by pyrrole-based tetradentate Schiff bases720 as well as Ln(n) and Ln(lll) meso-... 

Pyrrolyl ligand and analogous N-heterocycles are isoelectronic with the Cp ring. Titanium complexes with this type of ligands have been described (Section 4.05.7). 

Pyrrolyl ligands -coordinated to titanium give less stable compounds than the isoelectronic Cp group, and 75-pyrrolyltitanium derivatives are relatively rare. 

In 2003, Arnold and coworkers developed a series of bis-pyrrolyl Sm and Y complexes by using the steric more demanding pyrrolyl ligand L7. Compared with L6, L7 has a /Bu group at 5-position of the pyrrole ring. [Sm(L7)2Cl(THF)] (31) was... 

TABLE 6,1. Melal complexes of pyrrole and pyrrolyl ligands. 

Ihe interaction of polynuclear metal complexes with pyrrole-type molecules has also attracted some attention, and it is interesting in connection with possible interactions with surfaces, where vicinal metal atoms may simultaneously interact with the pyrrole molecule. Cluster compounds containing intact coordinated pyrrole ligands are not known, since this reaction invariably involve N-H and/or C-H bond activation to yield derivatives most frequently containing bridging pyrrolyl ligands, as exemplified in Eig. 6.2. 

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