Neutral monodentate ligands

Au( N) CI3 adducts are readily obtained by reaction of AU2CI6 or [ AuCU] with a variety of substituted heterocyclic ligands including 2-phenylpyridine [9], 2-benzylpyridines [10], 

Under comparable conditions, no ortho-metallated species are obtained from the 1-phenyl-pyrazole (1-Phpz) adduct, Au(N)Cl3, formed by reaction of 1-Phpz with Na[AuCl4] [17[. 

As in the case of 2-substituted pyridine adducts, activation of an aromatic C—H bond is observed when the adducts of 6-thbipy and of 6-Bnbipy are heated under reflux in aqueous media. A cyclic dimer (1) with bridging N,C ligands is obtained in the first case [24], while cyclometallated derivatives [Au(N, N,C)C1] (2) are formed in 

In the latter case, a dinuclear oxo bridged complex [Au2(N,N)2(p,-0)2][BF4]2 is also formed in small amounts. The same oxo complexes are obtained in high yields, as the 

Pp6 salts, with all the 6-Rbipy ligands by reaction of the Au(6-Rbipy)Cl3 adducts 3 (R = Me, Et, iPr or neoPn) with AcONa and excess KPFfi in aqueous media [25] (Equation 2.1). 

---

L = neutral monodentate ligand L-L = neutral bidentate ligand X = halide ligand Ar = aromatic ligand Cp = cyclopentadiene. 

NiL(Pts)](C104)2 D PS3L TBPy L = neutral monodentate ligands 1408... 

L Generally a neutral monodentate ligand (unless otherwise indicated)... 

The process we are seeing in the copper(II)-ammonia solution is a ligand substitution process, where one ligand is replacing another. In general, we can represent this, for reaction in aqueous solution with a neutral monodentate ligand at this stage, by Equation (5.1) ... 

Neutral Ni(II) complexes are most commonly of the types NiX2L2 (which may be tetrahedral or square planar) and NiX2L4 (usually octahedral) where X = anionic ligand and L = neutral monodentate ligand. The six coordinate complexes of the type NiX2L4 have spectra typical of octahedral Ni(II) complexes the V2 and V3 bands are not greatly affected by the low symmetry, but the vi band is frequently split into two components [46]. 

The catalytic cycle and the catalytic intermediates for the Rh-based process are shown in Figure 5.6. In the catalytic cycle L is a neutral monodentate ligand such as PPhj, P(OR)3, TPPTS, or even CO. The following few points are important and should be noted. 

---