C—Au bonds

The above analysis for copper chemistry also applies to the same-class element gold, which, however, forms much more stable C-Au bonds [176] and so is un-reactive. On the other hand, the d-orbitals of zinc(II), a main group neighbor, are too low-lying to make organozinc compounds as nucleophilic as organocopper compounds [92],... 

A particular case is that of d -d secondary interactions, first identified in gold compounds and described as aurophilic attraction [78-80], later generalized as metallophilic attraction [81]. This leads to supramolecular self-assembly in many gold compounds, especially when associated with three-center Au- -C Au bonds, and can be also found in other d metal compounds, such as silver, gold, and thallium complexes. Such supermolecules are illustrated by the quasi-cyclic pen-tamers Au5(Mes)5 and Cus(Mes)5, 33, and the tetramer Ag4(Mes)4, 34 [82]. 

The products of oxidation of a variety of olefins by tetrachloroauric acid in methanol have been investigated. Gold(iii) acts as an electrophile and gives an organometallic adduct which decomposes by heterolysis of the C— Au bond. A comparison made between the products resulting from oxidations with thallium(iii) and lead(iv) showed that the differences could be explained either in terms of... 

M-C(t bonds can be formed by each of the metals. The simple alkyls and ai7ls of Ag are less stable than those of Cu while those of Au have not been isolated. Copper alkyls and ai7ls are prepared by the action of LiR or a Grignard reagent on a Cu halide ... 

The optimum coefficients in Equation 2 are Eq -37.8363 and E =-0.5685 au. Eq is very close to the value -37.8366 found for the pure graphite clusters. The value of E corresponds to a contribution of 47.1 kcal/mol to the total energy of Cg 2Hg for each bonded H-atom (the hydrogen atom has an energy of -0.4935 au in the oasis set used). Alternatively, the parameter values can be interpreted as 83.3 kcal/mol per C-C bond, 88.7 kcal/mol per C-H bond. 

The hydration of C-C triple bonds represents one of the most atom economical and environmentally friendly oxidation reactions [37], Recently, Nolan and co-workers reported the cationic [Au(lPr)][SbF ] system, which was generated in situ from [AuCl(lPr)] and AgSbF. The catalyst system showed remarkable activity in the hydration of a large range of alkynes, at An loadings as low as 10 ppm (typically 50-100 ppm), under acid-free conditions (Table 10.6) [38],... 

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... 

Under comparable reaction conditions, no C—H bond activation is observed for adducts of 6-Phbipy and 6-Rbipy. Nevertheless, [Au(N,N,C)Cl] derivatives can be obtained with 6-Phbipy [18] and with 6-tBubipy (tBu = CMe3) [20]. The former is obtained by a transmetallation reaction of the arylmercury(II) derivative with [AuClJ, while activation of a C(sp )—H bond of the tert-butyl substituent is accomplished by reaction of the Au(N)Cl3 adduct 3 (N = 6-tBubipy) with AgBp4 in the presence of excess ligand (Scheme 2.2). 

The cyclic carbene complex shown in equation 3.4 was studied by X-ray diffraction [66], it shows a linear complex (angle C—Au—C 178.6(4)°) and the gold aryl bond distance is 1.993(10) A which is in accordance with such bonds in other known pentafluorophenyl complexes. The gold carbene carbon distance is 1.961(9) A, the dihedral angle between the planes formed by the two organic ligands is 5.35° and the shortest intermolecular Au—Au distance is 3.95 A. 

In mononuclear and polynuclear Au(CgF5)3 compounds (Tables 3.12 and 3.13 respectively) the Au-C Fs bond lengths in the fragments mutually in trans position are in the same range and the remaining Au(C6F5) displays different distances depending... 

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