Ferrocene hydroxyls

In addition to the nature of the cation at the adsorption site, the superhyperfine tensor can also give information on neighboring atoms further away. For example, OJ adsorbed on MgO exhibits a superhyperfine tensor ascribed to the presence of a nearby proton, presumably as a hydroxyl group (68) and this has been confirmed by isotopic labeling with deuterium (see Section IV,A). Superhyperfine tensors indicating the presence of nearby protons have also been reported for O J adsorbed on ferrocene deposited on porous Vycor glass (PVG) (120) and for alkylperoxy radicals supported on Ti02 (90). 

TMU 11, HMPA. Filled circles, Cp=,Co+/0 (Cp = pentamethylcyclopentadienyl) filled squares, Cp2 Co+/0 (Cpe= (carboxy-methyl)cyclopentadienyl) filled triangles, Cp2Co+/0 (Cp = cyclopentadienyl) open triangles, Cp2Fe+/0 open squares, (hydroxyl-methyl)ferrocenium/ferrocene [6a]. 

Ferrocenylphosphines, chiral. Hayashi et al.1 have prepared a large number of chiral ferrocenylophosphines, which have planar chirality owing to 1,2-unsymmetrical substitution on the ferrocene group. In addition, one of the substituents contains a chiral carbon atom. The most interesting phosphines have amino or hydroxyl groups in the side chain. These phosphines, in combination with transition metals, can promote highly efficient enantioselective reactions. 

L.S. Bean, L.Y. Heng, B.M. Yamin and M. Ahmad, Photocurable ferrocene-containing poly(2-hydroxyl ethyl methacrylate) films for mediated amperometric glucose biosensor, Thin Solid Films, 477 (2005) 104-110. 

In other examples, compounds in which a metal atom is already coordinated in a molecule can be used as a comonomer in an addition polymerization. Two examples involve the ferrocenes discussed in Chapter 6. The vinyl ferrocene molecule is shown in 7.14, and a similar vinyl manganese complex in 7.15.30 An alternative approach involves condensation polymerization. For example, if the R group in the ferrocene unit shown in 7.16 contains a hydroxyl group, it can be copolymerized with a diacid chloride. If it is an acid chloride, it can be copolymerized with a diamine. (This type of polymer is called a heteroannular chain if only one of the rings in the repeat unit is in the backbone, the polymer is called homoannular.)7 Similarly, the titanium complex shown in 7.17 is copolymerized with diacids or diols.30 Numerous other examples involving ferrocenes are discussed in Chapter 6. 

Steady ultraviolet irradiation of benzoyl-ferrocene in hydroxylic solvents was reported to cause the formation of solvated electrons263. However, no evidence of solvated electrons has been found in flash photolysis and N20 scavenger experiments264. ... 

An example concerns the hydrogen bond dynamics in selectively deuterated ferrocene-1,l -diylbis(diphenylmethanol-d1). In this structure, the molecules form hydrogen bonded dimers, with the oxygen atoms of four hydroxyl groups involved in a folded trapezium hydrogen bonding arrangement [33] shown schematically in Fig. 2 as a square. 

A relatively novel class of derivatives is obtained by the covalent incorporation of organometallic moieties into cellulose. For example, cellulose ferro-cenyl derivatives have been prepared by esterification of cellulose with an intermediate derived from ferrocene carboxylic acid and triphenyl phosphite in the presence of pyridine [84]. An enzymatically cleavable cellulose ester has been developed [85], and prodrugs have been coupled to the hydroxyl or carboxyl functions of C-terminal aromatic amino acids of cellulose peptide derivatives for controlled release applications [86]. 

Preparation. [(i )-a-(2-Naphthyl)aminomethyl]ferrocene was prepared in three steps from ferrocenyl 2-naphthyl ketone featuring an asymmetric CBS reduction with >99% ee (eq 1). After protection of the secondary hydroxyl group with an acetyl group, a nucleophilic displacement of the acetoxy group with an amino group proceeded with retention of stereochemistry. A range of different variations of [(i )-a-(2-naphthyl)aminomethyl]ferro-cene could be prepared using this sequence with similar efficiency. 

Boronic acid is reported to form esters with D-sorbitol in alkaline solution. Van Bekkum et al. suggest the formation of a monoester involving the eryf/rro-configured diol while a mono-and a diester may be formed over a f/rreo-contigured site [40]. Tridentate D-sorbitol is found to occupy three of four coordination sites of the boron center in a ferrocene derivative with its hydroxyl functions at C2, C3, and C5 [46]. 

Another popular host for molecular recognition studies in monolayers is thiol-derivatized cyclodextrin. Kaifer and coworkers have prepared monolayers from fi-cyclodextrin 19 in which all primary hydroxyls are replaced by SH groups. This compound can form up to seven gold-sulphur chemical bonds on the surface. These monolayers are incomplete to cover the gold surface completely, they were treated successively with ferrocene (to block the cyclodextrin cavities) and pentanethiol (to fill in the spaces between cavities). Cyclic voltammetry showed that the layers obtained bind ferrocene. Ferrocene trapped in the cyclodextrin cavities can be replaced by another known guest, electroinactive m-toluic acid444. 

Because 64 is not a large acceleration, Breslow et al. began searching for more active substrates. They did this by first constructing molecular models of the tetrahedral intermediate for acylation by a variety of esters. They then assessed the quality of the fit within the cavity. This procedure led to the testing of p-nitrophenyl ferrocenylacrylate, a compound whose ferrocene system can enter the cavity and, with a slight tilt, rest its side chain above a P-cyclodextrin hydroxyl ... 

---