Derivatization of surfaces via reaction of strained silicon-carbon bonds. Characterization by photoacoustic spectroscopy

Abstract

Ferrocene-centered reagents can be bound to the surface of high surface area (400 m2/g) silica by reaction of the silica with alkane solutions of (1,1 '-ferrocenediyl)dichlorosiIane (la), (1,1 '-ferrocenediyl)dimethylsilane (lb), or (l.l'-ferrocenediyl)diphenylsilane (Ic). Derivatization is not found when ferrocene itself is used as the derivatization reagent; ferrocene is easily washed from the silica powder by solvents which do not affect the ferrocene centers bound upon reaction of the silica with la-c. As determined by photoacoustic spectroscopy, derivatization with Ia-c results in ring opening of the strained C-Si-C linkage bridging the two cyclopentadienyl rings to yield a simple, monosubstituted ferrocene center attached to the surface. Surface -OH functionality apparently reacts in a manner analogous to homogeneous solution sources of -OH such as MeOH. Reaction of lb with MeOD yields [Fe(p5-C5H4D)(t;5-C5H4Si(OMe)Me2)]. Optical absorption spectral changes accompanying reaction of Ia-c with solution sources of -OH are consistent with the differences found in the photoacoustic spectra of the pure powders of Ia-c compared to the silica powders derivatized with these reagents. Reaction of silica powders derivatized with Ia-c with acidic solutions of benzoquinone results in the oxidation of the surface-confined ferrocene centers to ferricenium centers giving photoacoustic spectra nearly the same as that from an authentic sample of a pure ferricenium salt. The surfaceconfined ferricenium can be used to oxidize Ar,A',A",A,-tetramethyl-p-phenylenediamine (TMPD) to TMPD+• in solution; this reaction allows an estimate of the surface coverage at 10"11 mol/cm2.

Synthesis of poly(ferrocenylsilanes) with different molecular weight and their electrochemical behavior

“…The PFS were synthesized according to the literature, 6,[11][12][13] and the structure of the PFS is shown in Scheme 1.…”

Synthesis and Solution Self‐Assembly of Polyisoprene‐block‐poly(ferrocenylmethylsilane): A Diblock Copolymer with an Atactic but Semicrystalline Core‐Forming Metalloblock

“…10,11 Reactions between the dilithioferrocene-TMEDA complex and dichloroorganosilanes give a wide range of sila[1]ferrocenophanes with symmetrically and unsymmetrically substituted silicon atoms bearing alkyl or aryl groups (Scheme 2[A]). [12][13][14] Alternatively, chlorine has been introduced as a substituent through the reaction of Fe(η 5 -C5H4Li)2·TMEDA with SiCl4 or RSiCl3, which, via subsequent nucleophilic substitution reactions at the SiCl2-or SiClRbridge, provides a facile route to [1]ferrocenophanes with alkoxy, aryloxy, and amino substituents at silicon. 15 Hypercoordinate silicon-bridged [1]ferrocenophanes can also be synthesised from chlorosila[1]ferrocenophanes Fe(η 5 -C5H4)2SiRR' (R = R' = Cl or R = Me, R' = Cl) and Li or Fe(η 5 -C5H4)2SiCl(CH2Cl) and N-methyl-N-(trimethylsilyl)acetamide.…”

“…Solution state 1 H, 13 C, and 29 Si NMR spectroscopy is readily applicable for structural characterisation of PFSs, due to the presence of these NMR active nuclei in the polymer backbone or side-group structure. For example, NMR analysis has been used to investigate the tacticity of PFSs: ethylmethylsila[1]ferrocenophane underwent living anionic ROP to…”

Photoinduced FeCp Bond Cleavage and Insertion Reactions of Strained Silicon‐ and Sulphur‐Bridged [1]Ferrocenophanes in the Presence of Transition‐Metal Carbonyls

“…For example, sila [1]ferrocenophanes such as 2 (ER x = SiMe 2 ) ring-open upon treatment with a protic source, such as HCl and MeOH, which results in the cleavage of the ipso-Cp-CÀSi bond to yield 3 (X = Cl [38] or OH [17] respectively). Sila [1]ferrocenophanes also undergo thermal, [39,40] anionic [41] or transition-metal-catalysed [42,43] ringopening polymerisations (ROP), to give polyferrocenylsilanes through cleavage of the ipso-Cp-C À Si bond.…”

“…[12] Compound 11 is presumably formed by insertion of a photochemically generated [Fe(CO) 4 ] fragment into the Fe À Cp bond, followed by rearrangement of the carbonyl ligands. The insertion of the [Fe(CO) 4 ] moiety between the Cp rings dramatically increases the C(1A)-S(1)-C(1) angle in 11 (100.76 (17) o ) from the corresponding angle in 8 (89.03 (9) o ) [61] Compared to analogous structures, cis- [62] and [Fe 2 (CO) 2 …”