The monosubstituted ferrocenyl-amide phosphine ligands PPh2CH2CH2NHCOFc and (PPh2CH2CH2)2NCOFc and the disubstituted ferrocenyl-amide diphosphine (PPh2CH2CH2NHCO)2Fc have been synthesized and used to prepare the gold chloride derivatives [AuCl­(PPh2CH2CH2NHCOFc)], [Au2Cl2{(PPh2CH2CH2)2NCOFc}], and [Au2Cl2{(PPh2CH2CH2NHCO)2Fc}] or the silver species [Ag­(OTf)­(PPh2CH2CH2NHCOFc)2] and [Ag­(OTf)­(PPh3)­(PPh2CH2CH2NHCOFc)]. In the gold complexes the chloro ligands can be easily substituted by several biologically relevant thiolates such as 2-mercaptonicotinic acid, 2-thiocytosine, 2-thiouracil, 2-mercaptopurine, and 2,3,4,6-tetra-6-acetyl-1-thiol-β-d-glucopyranosato, affording the gold phosphine thiolate derivatives. In addition, the gold phosphine thiolates of the closely related 1,1′-bis­(diphenylphosphine)­ferrocene ligand have been prepared in order to compare their biological activities. The antiproliferative activity of these compounds has been tested by the MTT viability assay in two murine cell lines, NIH-3T3 (mouse embryonic fibroblasts) and PC-12 (pheochromocytoma of the rat adrenal medulla), and two human cell lines, A-549 (adenocarcinomic human alveolar basal epithelial cells) and Hep-G2 (hepatocellular carcinoma). The amide-phosphine ligands are not active, whereas the chloro-gold derivatives have good antiproliferative activity in the murine cell lines and very low activity in the human cell lines. The silver complexes are less active than the gold derivatives. The gold thiolate complexes have moderate to very good cytotoxic activity for all of the ligands, showing excellent IC50 values for the thiolate complexes of the amide-phosphines PPh2CH2CH2NHCOFc and (PPh2CH2CH2N)2COFc and dppf.

Phenol tri- and nonaallyl dendrons (3 and 7, respectively) were functionalized at the focal position to give the new triallyl dendrons 4 and 6 and the nonaallyl dendrons 11 and 13 that contain a iodoalkyl or a bromobenzyl termini. All these dendrons were used for the [FeCp]+-induced hexafunctionalization of hexamethylbenzene in [FeCp(eta6-C6Me6)][PF6] (1) under mild conditions in the presence of KOH. These reactions directly yielded the 18-allyl and 54-allyl dendrimers 9, 10, and 14 with a [FeCp(eta6-arene)]+ unit located at the dendrimer core. Cyclic voltammetry studies were recorded in THF and DMF with these metallodendrimers and compared with those of analogous dendrimers or complexes of smaller size that contain a [FeCp(eta6-arene)]+ unit at the core. The decreased rate of heterogeneous electron transfer when the dendritic size increases first disclosed by Diederich and Gross is confirmed. The variation of the redox potential of the Fe(II/I) redox system with increasing dendritic size is negligible even in a solvent of high dielectric constant such as DMF. This trend is attributed to fact that the involved "redox" orbital is buried on the metal center, well protected by the shell of alkyl chains (electron-reservoir nature), unlike in ferrocene. The chemical irreversibility increases in THF as the dendrimer size increases, due to more facile ligand substitution with THF at the 19-electron level when the chain bulk increases.

The ligands {[bis(2‐pyridyl)amino]carbonyl}ferrocene (L1) and 1,1′‐bis{[bis(2‐pyridyl)amino]carbonyl}ferrocene (L2) have been prepared by treatment of the mono‐ or 1,1′‐bis(chlorocarbonyl)ferrocene derivatives with dipyridylamine in a 1:1 or 1:2 ratio, respectively. The ligand properties of these compounds towards group 11 and palladium complexes have been studied. Ligand L1 coordinates to these compounds to give four‐coordinate [Cu(L1)2]+, [PdCl2(L1)] and [Ag(OTf)(L1)(PR3)] or three‐coordinate [Ag(OTf)(L1)] and [Au(C6F5)(L1)] compounds. The ligand coordinates in a chelate fashion in all cases. The reactivity of L2 is somewhat different because coordination to copper or silver atoms can take place through several pyridine units either from different cyclopentadienido rings, as in [Cu(L2)]+, [Ag2(OTf)2(L2)] and [Ag(OTf)(L2)(PPh3)], or from the same cyclopentadienido ring, as in [Ag2(OTf)2(L2)(PPh3)2]. Coordination as a bridging ligand for four gold atoms has also been achieved in [Au4(C6F5)4(L2)] and [Au4(L2)(PPh3)4](OTf)4. The ligands and some complexes have been characterized by X‐ray diffraction studies and show the presence of several hydrogen bonds that lead to supramolecular structures.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)