Bridging Aryl Ligands

Homodinuclear Neutral Complexes with Bridging Aryl Ligands... 

Complexes of the type [AuRL] may contain a great variety of organic ligands such as alkyl, aryl, vinyl, or alkynyl, whereas the neutral donor ligand L is most commonly a tertiary phosphine. Also many polynuclear complexes are known which have the C-Au-L moiety with bridging polyfunctional ligands. Alkyl- or aryl-gold(I) complexes are usually synthesized... 

It has been found in the meantime that reaction (1) is generalizable (752), and that oxidative additions of this type occur for such widely differing substrates H2Y as ethylene, benzene 130), cyclic olefins, alkyl and aryl phosphines, aniline 337, 406), and H2S 130), ail of which give the same product structure with a triply-bridging Y ligand. The stability of these third-row transition metal clusters has stiU prevented catalytic reactions of these species, but it is likely that similar ones are involved in olefin and acetylene reactions catalyzed by other metal complexes. 

Similarly, homologous cuprate and argentate derivatives have also been prepared and the crystal structures of both bromocuprate and -argentate species have been established by X-ray diffraction (Fig. 13). They consist of a MLi2 core, and each aryl ligand bridging... 

The deviation from the linearity at the gold atom (C-Au-As angle of 166.8(4)°) is only moderate if compared with other complexes with bridging mesityl groups, e.g., [Au5(mes)5].83 It is noteworthy that the mesityl bridge is not symmetrically disposed, in contrast with the usual symmetrical disposition of the aryl ligand in the examples mentioned above. 

Complexes (38) to (41) illustrate mononuclear Ir(I) complexes with N-donor ligands. The N2 ligand in (38) is introduced by the reaction of ArC(0)NNN with trans-IrCl(CO)(PPh3)2, and it is bound in an end-on fashion see End-On Coordination). Cation (39) contains Ir(III) and is formed from the neutral triazenido Ir(I) complex Ir(CO)(PPh3)(ArNNNAr) (Ar = aryl). The tetrazene ligand in (38) is a 4-electron donor, and complex (38) is an 18-electron complex. Pyrazine can act as a monodentate (41) or a bridging (42) ligand. ... 

One of the few examples in which an aryl ligand acts as the deprotonating agent to form an enolato ligand is the reaction of 121 with ethyl acetate to afford a rare example of a complex, 122, with a bridging instead of chelating diketonato ligand. In addition, a condensation reaction takes place". ... 

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