Ferrocenophane

Viotte, M., Gautheron, B., Kubicki, M.M., Mugnier, Y. and Parish, R.V. (1995) New Iron(II)- and Gold(l)-Containing Metallocenes. X-ray Structure of a Three-Coordinate Gold(l) Ferrocenophane-Type Representative. Inorganic Chemistry, 34 (13), 3465-3473. 

Other [AuCIL] complexes with monophosphines are those derived of o-carborane (427),2506 pyr-anoside group (428),2507 a-dimethylamino(3)ferrocenophan-2-yl,2508 calix[4]arene derived phosphites,25 or aminoxyl radical-substituted phosphines (429),2510 for which ferromagnetic interactions have been observed. 

Figure 25 The ring-opening polymerization of strained boron-bridged [ 1J ferrocenophanes (35a-c) to produce poly(ferrocenylboranes) (36a-c). (Adapted from ref. 57.)...

A PEO macroinitiator with Si — H end groups was prepared through the condensation of monohydroxy-terminated PEO with CISiMePhH in the presence of pyridine [130]. The presence of the Si —Ph moiety prevents the hydrolysis of the Si — O — C bond, due to steric factors. This macroinitiator was subsequently used for the synthesis of poly(ferrocenyldimethylsilane), PFS, to afford PEO-fc-PFS block copolymers. The ROP of the ferrocenophane was conducted catalytically using the Pt(0) Karstedt s catalyst in toluene at 25 °C (Scheme 55). Rather broad molecular weight distributions (higher than 1.3) were obtained. 

Elimination of hydrogen halides from dihalogenoorganylboranes by reaction with ferrocene-1,1 -dithiol resulted in l,3-dithia-2-boryl[3]ferrocenophanes.170 These borylferrocenophanes were air sensitive, but were characterized by NMR, MS, and elemental analysis.170 A series of l,3-dibora-2-X-[3]fer-rocenophanes (X=S, Se, Te) were prepared and characterized and the crystal structure of [Se N Pr2)BC5Fl4 2Fe] has been reported.171... 

In addition to the common methods of synthesis, it has been shown that the desulfurization of thioacetals yields organogermanes (Equations (7) and (8)) with excellent selectivity in some cases (Equation (9)).8 Ring-opening reactions of strained [l]ferrocenophanes furnish germanium-substituted ferrocenes9,10 (Equation (10)).9... 

Germanium-bridged [l]ferrocenophanes undergo a number of ring-opening polymerization reactions to yield ferrocene-containing polymers, and the versatility of this interconversion has been reviewed. A -GeMe2-... 

Recently, Plenio and co-workers have published a number of papers on ferrocenophanes, ferrocene cryptands and simple ferrocene amines (Plenio et ai, 1993, 1994 Plenio and Diodone, 1995a). They have synthesized 22... 

To conclude the matter of monoferrocene molecules we consider those cases in which the cyclopentadienyl substituents form bridges between the two rings. Such derivatives are named ferrocenophanes. The best known ferrocenophanes are those which contain saturated (tri- or tetra-methylene) carbon chains. Like ferrocenes, these molecules also exhibit reversible one-electron oxidation to the corresponding ferrocenium ions. 

For example, for the trimethylene-bridged derivative [Fe( 75, 5-C5H4(CH2)3C5H4)] (also known as [3]ferrocenophane) the oxidation... 

It is noted that there are also ferrocenophanes in which the bridge is formed by heteroatoms. For example, Figure 8 shows the molecular structure of ferrocenophanes containing one16 or two17 trisulfur bridges. 

Figure 8 X-Ray structures of (a) 1,2,3-trithia[3]ferrocenophane. Fe-C average bond length 2.044 A. (b) [3](1,] )[3J(2,2/)(l,2,3)trithia-ferrocenophane. Fe-C average bond length 2.043 A...

Attempts to make C2-symmetric ferrocenes by double lithiation of a bis-acetal met with only limited success . A second lithiation of the ferrocenylacetal 298 leads to functionalization of the lower ring of the ferrocene, in contrast with the second adjacent lithiation of the oxazolines described below. This can be used to advantage if, for example, the first-formed aldehyde 301 is protected in situ by addition of the lithiopiperazine 53 °, directing f-BuLi to the lower ring (Scheme 139) °. The same strategy can be used to introduce further functionalization to products related to 302. For example, silane 303, produced in enantiomerically pure form by the method of Scheme 138, may be converted to the ferrocenophane 304 by lithiopiperazine protection, lithiation and functionalization (Scheme 140) . 

The silicon-bridged [l]ferrocenophane LXXXV undergoes polymerization at 120-150°C to yield polymers of number-average molecular weights up to 105 with PDI 1.5-2.5... 

The sequential addition method also allows the synthesis of many different block copolymers in which the two monomers have different functional groups, such as epoxide with lactone, lactide or cyclic anhydride, cyclic ether with 2-methyl-2-oxazoline, imine or episul-Hde, lactone with lactide or cyclic carbonate, cycloalkene with acetylene, and ferrocenophane with cyclosiloxane [Aida et al., 1985 Barakat et al., 2001 Dreyfuss and Dreyfuss, 1989 Farren et al., 1989 Inoue and Aida, 1989 Keul et al., 1988 Kobayashi et al., 1990a,b,c Massey et al., 1998 Yasuda et al., 1984]. 

The monofunctional ferrocenol reacts with carboxylic acid chlorides to give di- or trinuclear ferrocenol esters, depending on the structure of the acid chloride. The corresponding reaction of the bifunctional l,l -ferrocenediol leads to either mononuclear [n] ferrocenophanes or dinuclear [n.n ferrocenophanes, depending on the nature of the acid chloride. ... 

Figure 35. The molecular bond graph of a ferrocenophane derivative.

Figure 36. The 4-rung Mdbius ladder which is contained in ferrocenophane.

Using this theorem we can prove that various molecular graphs are intrinsically chiral. We shall illustrate by proving that the graphs of a ferrocenophane derivative molecule [26] and the Simmons-Paquette molecule [29, 30] are both intrinsically chiral. (Note that Liang and Mislow observed the intrinsic chirality of this ferrocenophane derivative as well as many other molecules [21].)... 

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