Ligands jr-acceptor

The reaction of tris(jr-allyl)chromium with the jr-acceptor ligand PF3 produces stable crystals of [Cr(PF3)6] via [(C3H5)3Cr(PF3)] (Scheme 9). At high pressure, only [Cr(PF3)6] is isolated 60 it can also be obtained by metal vapour synthesis, 1 and its He(I) PE spectrum has been assigned.62... 

Bidentate heterocyclic chelate ligands see Bidentate Ligand) such as bipy, phen, and their substituted derivatives (LL) form tris-chelate complexes of the type [Os(LL)3] +, the Os oxidation state being stabilized by these jr-acceptor ligands. A wide variety of methods can be employed to... 

Thiazyl monomer can be stabihzed by coordination to a metal, and many thionitrosyl complexes with Cr, Mo, Re, Ru, Os, Co, Rh, Ir, and Pt are known. Comparison of the spectroscopic properties and the electronic stmctures of M-NS and M NO complexes indicates that NS is a better a-donor and jr-acceptor ligand than NO. Oxygen transfer from an NO2 to an NS ligand on the same metal center occurs in ruthenium porphyrin complexes. ... 

Complexes with several 7r-donor or jr-acceptor ligands... 

When the six double-face r-donor or jr-acceptor ligands are identical, octahedral symmetry is preserved. We therefore find the usual splitting pattern in the d block, into two groups of degenerate orbitals, whose symmetries are t2 and tg. We shall now use the method set out in the preceding section to determine the shapes of the MO and the energetic consequences of the tt interactions. 

Figure 3.8. Perturbation of the d block (in the centre, a interactions only) of an octahedral complex MLs by the jr interactions with double-face jr-donor ligands (L = Cl, for example) on the left, and double-face jr-acceptor ligands (L = CO, for example) on the right.

Breit B, Winde R, Mackewitz T, Paciello R, Harms K (2001) Phosphabenzenes as monodentate jr-acceptor ligands for rhodium-catalyzed hydroformylation. Chem Eur J 7 3106-3121... 

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