Ferrocene-based

Guldi D M, Maggini M, Scorrano G and Prato M 1997 Intramolecular electron transfer in fullerene/ferrocene based donor-bridge-acceptor dyads J. Am. Chem. See. 119 974-80... 

Heterometallic ferrocene-based transition metal compounds. P. N. Gaponik, A. I. Lesnitovich and Y. G. Orlik, Russ. Chem. Rev. (Engl. Transl), 1983,52,168-183 (293). 

Recently a novel chiral ferrocene-based amidinato ligand and its rhodium complexes have been described. The chiral N,N -bis(ferrocenyl)-substituted formamidine (N,N -bis[(S)-2- (lR)-l-(diphenylphosphino)ethyl ferrocen-l-yl]for-mamidine was prepared from commercially available (IR)-l-(dimethylamino) ethyl ferrocene by a multistep procedure in an overall yield of 29%. Deprotonation of the ligand with -butyllithium followed by addition of [RhCl2(COD)2] as illustrated in Scheme 167 yielded the corresponding (formamidinato)rhodium(l)... 

Scheme 1.75 Ferrocene-based sulfur-imine ligands for Pd-catalysed allylic alkylations.

The electrochemical behavior of ferrocene-based polymers [15] and of complexes containing a large, well defined number of ferrocene-type units [16] had already been reported when several groups became interested in dendrimer research. In the past few years several dendrimers of different chemical nature and structure carrying ferrocene-type units in the periphery have been synthesized... 

Getty SA, Engtrakul C, Wang L, Liu R, Ke S-H, Baranger HU, Yang W, Fuhrer MS, Sita LR (2005) Near-perfect conduction through a ferrocene-based molecular wire. Phys Rev B 71 241401... 

Figure 6 Chiral ferrocene-based bisphosphane ligands.

A series of non-f, -symmetrical ferrocene-based 1,5-diphosphane ligands (TaniaPhos) has been developed by Knochel.88,88a,88b The ligands have been effectively used in Rh- or Ru-catalyzed asymmetric hydrogenations. The ligand 39, which has an MeO group at the chiral carbon center, has shown excellent applications in the hydrogenation of several olefin and ketone substrates.89 Weissensteiner and Spindler have reported a series of structurally different... 

Fu has reported a planar-chiral bisphosphorus ligand 45 with a phosphaferrocene backbone. The ligand has provided enantioselectivity up to 96% ee in the hydrogenation of a-dehydroamino acid derivatives.99 Another planar-chiral ferrocene-based bisphosphorus ligand 46 has been reported by Kagan recently and enantioselectivity up to 95% ee has been obtained in the reduction of dimethyl itaconate.100... 

One of the branches in ligand design was provided by Kumada and his introduction of the ferrocene backbone for BPPFA [99-101] (20a) and BPPOH [102] (20b). This development leads us to the next class of ligands - ferrocene-based. Other variations for development include changes in the backbone and incorporation of the phosphorus into a phospholane (see Section 23.6). 

The rhodium complexes of the ferrocene derivatives 39 have shown useful characteristics for the reduction of itaconates as well as dehydroamino acid derivatives [15, 167-170]. These compounds are hybrids between ferrocene-based ligands and the various other types. The P-chiral compounds, which in some ways are DIPAMP hybrids, showed tolerance for the reduction of N-methyl en-amides to produce N-methyl-a-amino acid derivatives [169-171]. 

Enantioselective Hydrogenation of Alkenes with Ferrocene-Based Ligands... 

Fig. 25.1 Structures of Ugi s amine and the first ferrocene-based chiral phosphine ligands.

Fig. 25.5 Generic structures and names or numbers of ferrocene-based diphosphines with P bound to both Cp rings.

Ferrocene-based complexes have some potential for the enantioselective reduction of ketones, but compared to other ligand classes this is relatively limited [3]. Rh complexes of bppfa, bophoz and josiphos are among the most selective catalysts for the hydrogenation of a-functionalized ketones (Table 25.9 Fig. 25.18, 30-32). Ru complexes of walphos and ferrotane are quite effective for... 

As a general mle, most phospholanes are relatively air-sensitive and usually sold as rhodium-diene complexes. The ferrocene-based ligands, as well as phos-phoramidites and phosphites, are relatively easy to handle, and the corresponding Rh, Ir and Ru complexes are usually prepared in situ. Even though most biaryl type ligands are quite insensitive, most of them are applied as preformed Ru complexes. 

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