Aryls homoleptic

Examples of silver(l) alkyl and alkenyl (including aryl) complexes have been known from as early as 1941 6-9 however, the number of examples is fairly limited with respect to that of the heavier congeners, copper(l) and gold(l). Such a phenomenon can readily be attributed to the relatively low stability of this class of complexes, both photochemically and thermally. Simple homoleptic alkyl and alkenyl complexes of silver(i) are known to be very unstable under ambient temperature and light, and successful isolation of this class is fairly limited and mainly confined to those involving perfluoroorganics.10 The structures and the metal-carbon bond-dissociation energies for... 

The title ligands are the monoanionic 6-10 and the dianionic 11 and 12. Doubly deprotonated diazacrowns have also featured in Ln " chemistry, as well as A,A -dianionic macrocycles. Exceptionally, an [N(H)aryl] ligand figured as a chelate, implicating the aryl 7i-electrons, as in 2. ° Structurally characterised complexes using these ligands included [Nd(6)3], Li[Ho(7)4] (the homoleptic compound was not accessible from H0CI3 I Li N-... 

Preparative routes to homoleptic alkyls/aryls must take account of the sensitivities of the products, as well as the usual thermodynamic and kinetic factors. The following will serve as examples. 

Homoleptic chromium aryl compounds, preparation and characterization, 5, 298... 

Homoleptic germylenes, preparation and properties, 3, 773 Homoleptic lanthanide(II) alkyl compounds, properties, 4, 4 Homoleptic manganese aryl complexes, preparation, 5, 816 Homoleptic manganese isonitrilates, preparation, 5, 773—774 Homoleptic molybdenum complexes, preparation and characteristics, 5, 514... 

The efficiency of functionalized cyclopentadienyl complexes is meanwhile well established [78,191-202]. Because cyclopentadienyl ligands still dominate the field of organolanthanide chemistry, a selection of the functionalized ligands utilized is depicted in Fig. 11. In the field of aryl complexes, which represented the first well-characterized homoleptic derivatives [203], multiple functionalization has already been started [204]. 

M. M. Olmstead, P. Power, and S. C. Shoner, Isolation and X-Ray Crystal Structures of Homoleptic, Transition-Metal Aryl Complexes [(LiEt20)4VPh5] and [(LiEt20)3CrPh5], Organomeiallics 1, 1380-1385 (1988). 

S. U. Koschmieder, and G. Wilkinson, Homoleptic and Related Aryls of Transition Metals, Polyhedron 10, 135-173 (1991). 

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