Article pubs.acs.org/Organometallics
Carbosilane Metallodendrimers with Titanocene Dichloride End Groups Tomás ̌ Strašaḱ ,† Jan Č ermák,*,† Jan Sýkora,† Jiří Horský,‡ Zuzana Walterová,‡ Florian Jaroschik,§ and Dominique Harakat§ †
Institute of Chemical Process Fundamentals, v.v.i., Academy of Sciences of the Czech Republic, Rozvojová 135, 165 02 Prague 6, Czech Republic ‡ Institute of Macromolecular Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic § Institut de Chimie Moléculaire de Reims, UMR, CNRS 7312, Case postale 44 UFR des Sciences Exactes et Naturelles, BP 1039, 51687 Reims Cedex 2, France S Supporting Information *
ABSTRACT: Carbosilane metallodendrimers containing substituted titanocene dichloride end groups were prepared using hydrosilylation as the capping reaction. Two complementary pathways were followed: hydrosilylation of ω-alkenyl-substituted titanocene dichloride complexes with Si−H bond terminated dendrimers and hydrosilylation of vinyl terminated dendritic materials with 3-(dimethylsilyl)propyl-substituted titanocene dichloride. The former procedure provided dendrimers of the first generation with four end units and of the second generation with eight end units. The latter method gave dendrititic wedges and dendrimers up to the second generation with 16 peripheral titanocene dichloride units and molecular weight 7070 Da. Dendritic materials were purified by GPC and characterized by MALDI-TOF mass spectrometry and ESI-TOF mass spectrometry (metallodendrimers) and also by multinuclear NMR.
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entiation between types of dendrimers4 and recently with organocatalysis by dendrimers5 are also available. Catalysis by an active site attached to a dendrimer, be it a metal complex or some other sort of catalytic site, meets many of the criteria that an ideal catalyst recycling method should have. Separation, importantly even in a continuous flow reactor, may be achieved by nanofiltration or similar methods.4c,6 We have been interested in cyclopentadienyl transition-metal complexes for catalytic applications for some time, since the cyclopentadienyl ligand offers certain advantages as a binding ligand, e.g. a strong η5 coordination mode, usually making it a spectator ligand or offering the possibility of stereoelectronic tuning of ligand properties.7 Several groups of authors reported cyclopentadienyl complexes on dendritic materials. Cyclopentadienes and cyclopentadienyls at the focal points of dendritic wedges were reported by Andrés et al.;8 however, we wish to concentrate on cyclopentadienyl complexes at the periphery, since they offer a much higher density of metal sites per unit of polymer material. Although cyclopentadienyl metal complexes were reported to be attached to dendrimers also via atoms other than the carbon of the cyclopentadienyl ring,9 we concentrated on Cp -ring-
INTRODUCTION
Dendrimers as a class of nanoscopic materials belong to the fastest-growing group of materials in modern chemistry, with numbers of publications currently counted in the tens of thousands. Dendrimers (and also hyperbranched polymers) have found multiple applications, catalysis by dendritic materials being among the most important. In the multitude of dendrimer types, those containing silicon−carbon bonds1 adopt a special position, owing to the fact that their properties are very suited for catalytic applicationsthermal and hydrolytic stability, nonpolarity, inertness, and neutral character based on the absence of polar bonds which is especially true for carbosilane dendrimers, i.e. dendrimers containing only Si−C bonds in their interior. In addition to that, carbosilane dendrimers allow relatively easy control of branching degree and thus dendrimer density and of distribution of catalytic sites which may be at the focal points of dendritic wedges, at the branching points of dendrimers, or at their periphery. The first catalysis by dendrimers was reported in 1991.2a Since 1994, when a seminal work of van Koten and co-workers2b on the application of metal-containing carbosilane dendrimers in catalysis appeared, the whole field grew considerably and catalysis by metal complexes attached to carbosilane dendrimers has been reviewed.3 Numerous reviews dealing with catalysis by metallodendrimers without differ© 2012 American Chemical Society
Received: June 19, 2012 Published: September 24, 2012 6779
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Scheme 1. Synthesis of ω-Alkenyl-Substituted Titanium Complexes
attached species, since otherwise the advantage of binding a complex via a spectator Cp ligand would have been lost. In the category of the latter materials, ferrocene-containing dendrimers developed mainly by groups in Madrid and Bordeaux play a dominant role.10 However, in those metallodendrimers the method of attaching the cyclopentadienyl moiety is rather specific due to the aromatic character of ferrocene, so that the relatively robust ferrocene part is always attached intact. Also, the importance of the ferrocene site in traditional homogeneous catalysis is comparably small; on the other hand, ferrocene-containing materials find broad application e.g. in areas where their redox properties are important, including electrocatalysis.10n So far only a few papers have reported other metallodendrimers where metals are bonded via Cp ligands. Carbosilane dendrimers with cyclopentadiene end groups were prepared by Cuadrado et al. and used to synthesize CpCo(CO)2 units at the periphery of the first-generation dendrimer.11 In the patent literature, Seyferth reported ethylidene carbosilane dendrimers with varied numbers of titanocene, zirconocene, and hafnocene dichloride end groups and also their use for polymerization.4j,12 Later Lang et al. described the synthesis of titanocene dichloride complexes at the periphery of carbosiloxane dendrimers,13 which are not as stable as carbosilane dendrimers, however.6g Recently, de Jesús and co-workers reported the synthesis of first- and secondgeneration dendrons containing [Cp2MCl2] (M = Ti, Zr) end groups and Si−Cl focal-point bonds.14 In their work the end groups were introduced by quantitative reactions of [CpMCl3] complexes with deprotonated cyclopentadiene end groups. Here we bring the results of attachment of titanocene dichloride units to carbosilane dendrimers using hydrosilylation as the capping reaction. Titanocene dichloride was chosen as a typical representative of cyclopentadienyl metal complexes important in catalysis. Also, [Cp2TiCl2] is well-known to exhibit antitumor biologic activity as the first metallocene compound that entered clinical trials.15 Its attachment to dendrimers of various sizes may therefore be of interest to those dealing with targeted transport of substances to cells.
mixed-ligand titanocene dichlorides [(η 5 -C 5 H 5 )(η 5 C5H4(CH2)nCHCH2)TiCl2] (3a−c) were prepared by the reaction of CpLi with the trichlorides 2a−c. First- and secondgeneration dendrimers with terminal Si−H bonds were prepared as previously reported in our group.16f Titanocene dichlorides 3a−c were finally reacted with dendrimers containing peripheral Si−H bond under catalysis by the Karstedt complex (Scheme 2). NMR spectra were in accordance with the proposed structures 4a−c and 5c. Notably, signals of vinyl protons of 3a−c completely disappeared from the 1H NMR spectra, giving rise to methylene signals overlapped with other methylene signals of dendrimer branches. In 13C NMR spectra the same process was demonstrated by the disappearance of vinyl carbon signals around 115 and 137 ppm of the complexes and the appearance of signals around 15 and 24 ppm assigned to the products. Further confirmation of the successful reaction was provided by 29Si NMR spectra, in which signals of the Si1−H terminated dendrimer at about −13 ppm disappeared and new signals between 1.5 and 1.7 ppm appeared. Compounds 4a,b were also investigated by mass spectrometry. Although MALDI-TOF MS can be used for ferrocene or cobaltocenium terminated dendrimers,10l,m,17 this technique failed with titanocene dichloride terminated dendrimers. Therefore, ESI-TOF MS, an analytical tool increasingly used for the analysis of sensitive organometallic compounds due to its mild working conditions,13,18 was used instead. Compounds 4a,b were dissolved in a mixture of dichloromethane and 1.0 mM sodium acetate/acetonitrile solution. Despite their high molecular weights, satisfactory high-resolution data could be obtained for the [M + Na]+ ions of 4a,b at m/z 1999.7 and 1943.6, respectively. In addition, for compound 4a the dicationic species [M + 2Na]2+ centered at m/z 1014 was also observed. In our hands the inverse hydrosilylation method gave satisfactory results with the first-generation dendrimers. With the second generation yields were low and crude products contained many impurities which had to be removed by chromatography. The result may be related to known inherent drawbacks of the inverse hydrosilylation methodthe bulky silicon hydride reactant can hardly be used in excess as is usual in hydrosilylation. Therefore, we turned our attention to the normal hydrosilylation method. To separate the silicon substituent from titanium, we wanted to connect the Cp ring with a substituent containing a Si−H bond through a three-carbon spacer, but the
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RESULTS AND DISCUSSION In general, there are two most often used strategies for attaching transition metal complexes to carbosilane dendrimers by hydrosilylation,1b the so-called “normal” hydrosilylation, when the double-bond-terminated dendrimer is reacted with a complex containing substituents with Si−H bonds, and “inverse” hydrosilylation, when a dendrimer terminated with Si−H bonds (usually obtained by reduction of Si−Cl bonds with LiAlH4) is treated with a complex containing ω-alkenyl substituents. The latter strategy was successfully applied to the synthesis of ferrocenyl carbosilane dendrimers.10d In addition to that, ωalkenyl-substituted titanium complexes seemed to be easier to synthesize than the corresponding silyl-substituted derivatives and we also had some experience with the reduction of Si−Cl to Si−H terminal bonds in dendrimers;16f therefore, the inverse hydrosilylation was the method of choice for us. Synthesis of ω-alkenyl-substituted titanium complexes was started from (ω-alkenyl)tetramethylcyclopentadienes, which were first deprotonated and reacted with [TiCl(O-iPr)3] to give the tris(isopropoxy) complexes 1a−c (Scheme 1). These compounds were then converted to the corresponding monocyclopentadienyl titanocene trichlorides 2a−c. The 6780
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Scheme 2. Metallodendrimers via Inverse Hydrosilylation
other hand, using propanediyl branches in the interior enabled higher flexibility and lower density in comparison to dendritic materials with ethanediyl branches only. 1H NMR spectra of the products show the characteristic pattern of vinyl groups, three doublets of doublets with geminal coupling constant 4.1 Hz and vicinal coupling constants 3Jtrans = 20.0 Hz and 3Jcis = 14.7 Hz. Defects in dendrimer structures, if present, could be easily detected in the region of vinyl groups. Signals of methylene protons of propanediyl branches were in some instances overlapped, this feature being more frequent in higher generation dendrimers. MALDI-TOF mass spectra of dendrimers 10−13 measured with silver trifluoroacetate as the ionizing agent agreed well with theoretical values and thus confirmed the assigned structures. Hydrosilylation of dendritic wedges and dendrimers 8−13 with complex 7 used in a slight excess gave the dendritic materials 14−19 (Figure 2). The commercial Karstedt catalyst was used in toluene at room or moderately increased temperature, and the course of the reactions was monitored by 1H NMR. Starting compounds were characterized by Si−H protons (complex 7) and protons of vinyl groups (wedges 8 and 9 and dendrimers 10−13). A slight overlap of the latter signals in the region of 5.6−6.2 ppm with signals of Cp rings did not prevent this monitoring. On the other hand, products were characterized by a broad singlet around 0.32 ppm resulting from the two methylene groups (formed by the addition of Si−H bond to vinyl groups) between the two outermost silicon atoms. Crude products still containing residual signals of complex 7 or its decomposition product siloxane but not the signals of vinyl groups were purified by GPC, giving pure compounds as red solids stable in air in the solid state. In case residual vinyl groups were still present in the reaction mixtures, fresh complex 7 and the Karstedt catalyst were added and the reaction continued until all vinyl signals disappeared. 13 C NMR spectra of pure products show four signals of cyclopentadienyl ligands (one for Cp and the other for the substituted ring); the absence of characteristic vinyl signals confirms complete hydrosilylation. The two carbon atoms between the two outermost silicons are found at stronger field in comparison to other methylene carbons of propanediyl branches and of the spacer connecting the Cp ring. In accordance with earlier observations,16f molecules of THF solvent were found in dendrimer interiors, especially with second-generation dendrimers. The chemical shifts of those encapsulated molecules, which could not be removed by prolonged treatment under high vacuum, were shifted toward
corresponding substituted titanocene dichloride complex is unknown. It was synthesized from 3-iodopropyldimethylsilane (Scheme 3) in 61% yield as the red crystalline compound 7, Scheme 3. Synthesis of Complex 7
stable in air in the solid state. It was characterized by IR, NMR, and ESI-MS spectra; notably, the Si−H group was visible in IR (2109 cm−1) and also in in 1H (3.84 ppm) and 29Si (−13.12 ppm) NMR spectra. Dendrimers and dendritic wedges of the first and second generation terminated with Si−Cl bonds were prepared according to the literature16 and finally reacted with vinylmagnesium chloride to obtain dendritic wedges with 2 and 4 vinyl end groups and dendrimers with 4−16 vinyl groups at the periphery, 8−13 (Figure 1). Termination with vinyl groups was
Figure 1. Structures of vinyl-terminated dendrimers and dendritic wedges.
chosen to limit the double-bond isomerization which may represent a serious problem in allyl terminated dendrimers.16f Núñez et al. also observed a considerably improved yield of products when reacting an (ω-dimethylsilyl)propyl-substituted carborane with tetravinylsilane in comparison to the reaction with tetraallylsilane in their study of the attachment of carborane derivatives to carbosilane frameworks.19 On the 6781
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Figure 2. Structures of metallodendrimers and dendritic wedges made via a normal hydrosilylation method.
higher field sufficiently enough to differentiate them from the molecules of free solvent. 29Si NMR spectra clearly distinguish between different silicon environments. The outermost silicons give signals around 3.9 ppm and the nearest silicon atoms with two methyls resonate around 3.3 ppm, whereas those atoms with one methyl and two branches resonate at about 5.5 ppm. The core silicon atom is found at about 0.5−0.7 ppm. ESI-MS spectra of compounds 14 and 16 show the [M + Na]+ ions at m/z 1031 and 1951, respectively. For compound 16 a signal corresponding to the loss of one chloride [M − Cl]+ at m/z 1898 was also observed. In the negative mode, the spectrum of 14 shows a signal for [M + Cl]− at m/z 1045, indicating chloride rearrangement during the measurement. The observation of a dicationic species for 4a encouraged us to examine compounds 17 and 18 with molecular weights of 3379 and 4180 Da, respectively, approaching or exceeding the detection limits of monoionic species (4000 Da) of our MS machine. However, despite multiple attempts and increasing the Li and Na ion concentrations of the solutions, no mono- or multiionic species could be detected. In conclusion, we prepared the first carbosilane dendrons and dendrimers with peripheral titanocene dichloride groups bonded via cyclopentadienyl rings in higher than the first generation. Up to 16 titanocene dichloride units were attached to the periphery, giving compounds with molecular weights up to 7070 Da. The attachment reaction was hydrosilylation, and the two methods inverse and normal hydrosilylation were
tested and compared. The normal hydrosilylation employing a double bond terminated dendrimer and Si−H bond in the titanocene dichloride complex gave better results in terms of yield and purity of products. The use of these new dendritic materials as catalysts in organic synthesis is currently under investigation and will be published in due course.
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EXPERIMENTAL SECTION
General Procedures. All syntheses were carried out under an argon atmosphere using Schlenk or drybox techniques. The organic solvents used were dried and purified according to standard procedures and stored under argon. Literature procedures were followed in the preparation of (ω-alkenyl)tetramethylcyclopentadienes,20 3-iodopropyldimethylsilane,21 diallyldimethylsilane,22 and Si−Cl bond and Si−H bond terminated carbosilane dendrimers.16 Vinylmagnesium chloride (1.6 M solution in THF), Karstedt’s catalyst (obtained as a 2−3% solution in xylenes), and cyclopentadienylsodium (2 M solution in THF) were purchased from Aldrich. LiAlH4 (4 M solution in diethyl ether) and [(η5C5H5)TiCl3] were obtained from Acros Organics and used as received. 1 H, 13C{1H}, and 29Si{1H} NMR spectra were recorded on Varian Mercury/Inova 300 and 500 MHz spectrometers. Chemical shifts (δ/ ppm) are given relative to the solvent signal (CDCl3: δ(H) 7.26, δ(C) 76.99) or the internal standard hexamethyldisilane (29Si). Preparative GPC: Watrex Chromatograph with UV detection (310 nm), PLgel column (Polymer Laboratories, 250 × 4,6 mm, particle size 5 μm, pore size 300 Ǻ ), flow rate 5 mL/min of CHCl3. MALDI-TOF mass spectra were obtained with a BIFLEX III mass spectrometer (Bruker Daltonics) using the positive ion, reflectron 6782
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[TiCl3{η5-C5Me4(CH2CH2CH2CHCH2)}] (2b). Obtained by a procedure analogous to that for 2a, yield 81%. 1 H NMR: δ 1.48 (m, 2H, CH2 CH2 CH2), 2.13 (m, 2H, CH2CH2CHCH2), 2.38 (2 × s, 12H, CH3,tmcp), 2.86 (m, 2H, CH2,tmcp), 5.04 (m, 2H, CH2), 5.81 (m, 1H, −CH). 13C NMR: δ 14.3, 14.4 (CH3,tmcp), 28.8, 29.1, 29.7 (CH2CH2CH2), 115.5 (CH2), 137.3, 137.5, 138.0 (Ctmcp), 141.6 (−CH). [TiCl3{η5-C5Me4(CH2CH2CHCH2)}] (2c). Obtained by a procedure analogous to that for 2a, yield 84%. 1 H NMR: δ 2.16 (m, 2H, CH2CH2CHCH2), 2.38 (2 × s, 12H, CH3,tmcp), 2.97 (m, 2H, CH2,tmcp), 5.02 (m, 2H, CH2), 5.78 (m, 1H, −CH). 13C NMR: δ 14.4, 14.5 (CH3,tmcp), 28.8, 33.8 (CH2CH2), 115.5 (CH2), 137.3, 137.5, 138.1 (Ctmcp), 141.6 (−CH). [TiCl 2 {η 5 -C5 Me 4 (CH 2CH 2CH 2CH 2 CHCH 2 )}(η 5 -C 5 H 5 )] (3a). Complex 2a was dissolved in THF (20 mL) in a Schlenk flask and cooled to 0 °C and a solution of CpLi (0.60 g, 8.3 mmol) in THF (10 mL) slowly added. The reaction mixture was warmed to room temperature and stirred for a further 16 h. The solvent was removed under vacuum and the residue extracted with hexane (5 × 20 mL). The combined extracts were concentrated under vacuum to about 50 mL volume and the product crystallized at −30 °C. After filtration and drying under vacuum a dark red powder (2.18 g, 5.6 mmol) was obtained in 67% yield. 1 H NMR: δ 1.33 (m, 4H, CH2CH2CH2CHCH2), 2.06 (2 × s, 2 × 6H, CH3,tmcp), 2.10 (m, 2H, CH2CH2CHCH2), 2.47 (m, 2H, CH2,tmcp), 4.97 (m, 2H, CH2), 5.78 (m, 1H, −CH), 6.26 (CHcp). 13 C NMR: δ 13.4 (2 × CH 3,tmcp ), 28.4, 28.8, 28.9, 33.4 (CH2CH2CH2CH2), 114.7 (CH2), 119,8 (CH−cp), 129.3, 130.7, 133.9 (C tmcp ), 138.4 (−CH). HRMS (ESI): calcd for C20H28NaCl2Ti ([M + Na]+), 409.0945; found, 409.0943. [TiCl2{η5-C5Me4(CH2CH2CH2CHCH2)}(η5-C5H5)] (3b). Obtained by a procedure analogous to that for 3a, yield 64%. 1 H NMR: δ 1.42 (m, 2H, CH2CH2CHCH2), 2.06 (2 × s, 2 × 6H, CH3,tmcp), 2.12 (m, 2H, CH2CH2CHCH2), 2.54 (m, 2H, CH2,tmcp), 5.02 (m, 2H, CH2), 5.81 (m, 1H, −CH), 6.27 (CH−cp). 13C NMR: δ 13.4 (2 × CH3,tmcp), 28.1, 28.7, 33.8 (CH2CH2CH2), 115.1 (CH2), 119.8 (CHcp), 129.3, 130.8, 133.6 (Ctmcp), 137.9 (−CH). HRMS (ESI): calcd for C19H26NaCl2Ti ([M + Na]+), 395.0789; found, 395.0786. [TiCl2{η5-C5Me4(CH2CH2CHCH2)}(η5-C5H5)] (3c). Obtained by a procedure analogous to that for 3a, yield 62%. 1 H NMR: δ 2.06, 2.07 (2 × s, 2 × 6H, CH3,tmcp), 2.11 (m, 2H, CH2CH2CHCH2), 2.59 (m, 2H, CH2,tmcp), 5.02 (m, 2H, CH2), 5.80 (m, 1H, −CH), 6.27 (CHcp). 13C NMR: δ 13.5, 13.6 (2 × CH3,tmcp), 28.2, 33.6 (CH2CH2CH2), 115.5 (CH2), 120.0 (CHcp), 129.5, 130.7, 132.9 (Ctmcp), 137.4 (−CH). HRMS (ESI): calcd for C18H24NaCl2Ti ([M + Na]+), 381.0632; found, 381.0638. 4c. Complex 3c (100 mg, 0.28 mmol) was dissolved in 1 mL of toluene. The solution was treated with 1 drop of Karstedt’s catalyst solution and stirred for 5 min. Then Si(CH2CH2CH2SiMe2H)4 (27 mg, 0.063 mmol) was added. The mixture was stirred for 14 h at room temperature. Volatiles were removed at reduced pressure, and the crude product was purified by GPC with chloroform as the eluent. Yield: 42 mg, 0.022 mmol (36%) of a red oil. 1 H NMR: δ −0.05 (s, 24H, Si 1 CH 3 ), 0.54 (m, 24H, SiCH 2 CH 2 CH 2 Si, Si 1 CH 2 ), 1.34 (m, 24H, SiCH 2 CH 2 CH 2 Si, Si1CH2CH2CH2), 2.07 (s, 48H, CH3,tmcp), 2.46 (m, 8H, CH2,tmcp), 6.26 (s, 20H, CHcp). 13C NMR: δ −3.3 (Si1CH3), 13.5 (CH3,tmcp), 17.5, 18.5, 20.2 (SiCH 2 CH 2 CH 2 Si), 15.3, 24.5, 28.5, 33.5 (Si1CH2CH2CH2CH2), 119.8 (CHcp), 129.3, 130.7, 134.1 (Ctmcp). 29 Si NMR: δ 0.58 (Si0), 1.66 (Si1). 4b. Obtained by an analogous procedure from 3b, yield 35%. 1 H NMR: δ −0.05 (s, 24H, Si1CH3), 0.47 (m, 8H, Si1CH2), 0.55 (m, 16H, SiCH2CH2CH2Si), 1.32 (m, 32H, SiCH2CH2CH2Si, Si1CH2CH2CH2CH2), 2.07 (s, 48H, CH3,tmcp), 2.47 (m, 8H, CH2,tmcp), 6.28 (s, 20H, CHcp). 13C NMR: δ −3.3 (Si1CH3), 13.5 (CH3,tmcp), 17.6, 18.5, 20.3 (SiCH2CH2CH2Si), 15.4, 23.8, 28.7, 29.3, 33.9 (Si1CH2CH2CH2CH2CH2), 119.8 (CHcp), 129.3, 130.6, 134.2 (Ctmcp). 29 Si NMR: δ 0.56 (Si0), 1.54 (Si1). HRMS (ESI): calcd for C96H156NaSi4Cl16Ti4 ([M + Na]+), 1943.6377; found, 1943.6356. IR
mode, and delayed extraction. trans-2-[3-(4-tert-Butylphenyl)-2methyl-2-propenylidene]malononitrile, synthesized according to the literature,23 was used as a matrix and silver trifluoroacetate as an ionization agent. Samples for measurement were prepared by the dried-droplet method: solutions in tetrahydrofuran of the matrix (10 mg/mL), dendrimer (10 mg/mL), and ionizing agent (10 mg/mL) were premixed in the ratio 20:4:1, hand-spotted on the target plate (0.5−1 μL), and left to dry. Electrospray ionization mass spectrometry (ESI-MS): all experiments (MS and HRMS) were obtained on a hybrid tandem quadrupole/time-of-flight (Q-TOF) instrument, equipped with a pneumatically assisted electrospray (Z-spray) ion source (Micromass, Manchester, U.K.) operated in positive and negative mode. The electrospray potential was set to 3 kV, and the extraction cone voltage was usually varied between 30 and 80 V, the samples were dissolved in THF, acetonitrile, or dichloromethane and introduced continuously at a flow rate of 5 μL/min. In order to increase the Na concentration, a 1.0 mM sodium acetate solution in acetonitrile was used for the dendritic compounds. [Ti(O-iPr)3{η5-C5Me4(CH2CH2CH2CH2CHCH2)}] (1a). A butyllithium solution in hexane (1.6 M, 9.50 mL, 15.2 mmol) in a Schlenk flask was diluted with hexane (40 mL). The solution was cooled to 0 °C and a solution of (hex-5-enyl)tetramethylcyclopentadienes (mixture of regioisomers, 3.1 g, 15.2 mmol) in hexane (20 mL) slowly added. The reaction mixture was stirred a further 30 min at 0 °C and then 2 h at room temperature. The resulting precipitate was filtered off and dried under vacuum. A white powder of the lithium salt was obtained (3.12 g, 14.8 mmol). The powder was dissolved in THF (20 mL) and the solution slowly transferred to a solution of [TiCl(OiPr)3] in hexane. The reaction mixture was stirred for 16 h at room temperature, and then the solvent was evaporated and the crude product extracted with pentane (30 mL). After filtration and evaporation of the solvent the product was obtained as a light yellow viscous liquid (4.97 g, 11.6 mmol) in 78% yield. 1 H NMR: δ 1.11 (d, 3JHH = 6.1 Hz, 18H, OCH(CH3)3), 1.44 (m, 4H, CH2CH2CH2CH2), 2.00, 2.01 (2 × s, 2 × 6H, CH3,tmcp), 2.15 (m, 2H, CH2CH2CHCH2), 2.44 (m, 2H, CH2,tmcp), 4.50 (heptet, 3J = 6.1 Hz, 3H, O−CH(CH3)3), 5.01 (m, 2H, CH2), 5.85 (m, 1H, −CH). 13C NMR: δ 11.1, 11.2 (CH3,tmcp), 26.5 (OCH(CH3)3), 26.1, 29.6, 33.9 (CH2CH2CH2CH2), 74.8 (OCH(CH3)3), 114.3 ( CH2), 120.6, 121.1, 124.7 (Ctmcp), 138.8 (−CH). [Ti(O-iPr)3{η5-C5Me4(CH2CH2CH2CHCH2)}] (1b). Obtained by a procedure analogous to that for 1a, yield 72%. 1 H NMR: δ 1.11 (d, 3JHH = 6,2 Hz, 18H, OCH(CH3)3), 1.51 (m, 2H, CH2CH2CHCH2), 1.99, 2.01 (2 × s, 2 × 6H, CH3‑tmcp), 2.11 (m, 2H, CH2CH2CHCH2), 2.46 (m, 2H, CH2,tmcp), 4.57 (heptet, 3J = 6.2 Hz, 3H, OCH(CH3)3), 4.99 (m, 2H, CH2), 5.83 (m, 1H, −CH). 13C NMR: δ 11.2, 11.2 (CH3,tmcp), 26.5 (OCH(CH3)3), 26.3, 29.1, 30.0, 33.7 (CH2CH2CH2), 74.7 (O-CH(CH3)3), 114.2 ( CH2), 120.6, 121.1, 124.9 (Ctmcp), 139.0 (−CH). [Ti(O-iPr)3{η5-C5Me4(CH2CH2CHCH2)}] (1c). Obtained by a procedure analogous to that for 1a, yield 69%. 1 H NMR: δ 1.11 (d, 3JHH = 6,1 Hz, 18H, OCH(CH3)3), 1.99, 2.01 (2 × s, 2 × 6H, CH3,tmcp), 2.15 (m, 2H, CH2CH2CHCH2), 2.52 (m, 2H, CH2,tmcp), 4.57 (heptet, 3J = 6.2 Hz, 3H, OCH(CH3)3), 5.00 (m, 2H, CH2), 5.92 (m, 1H, −CH). 13C NMR: δ 11.2, 11.2 (CH3,tmcp), 26.5 (OCH(CH3)3), 26.1, 34.6 (CH2CH2), 74.8 (OCH(CH3)3), 114.2 (CH2), 120.6, 121.1, 124.0 (Ctmcp), 138.9 (−CH). [TiCl3{η5-C5Me4(CH2CH2CH2CH2CHCH2)}] (2a). In a Schlenk flask SiMe2Cl2 (7.49 g, 58.0 mmol) was added to 1a (4.97 g, 11.6 mmol) without a solvent. The reaction mixture was stirred for 32 h at room temperature, then the excess of the silane together with reaction side products was removed under vacuum. The product was washed with cold hexane and dried under vacuum. A dark red powder (3.02 g, 8.4 mmol) was obtained in 73% yield. 1 H NMR: δ 1.43 (m, 4H, CH2CH2CH2CH2), 2.08 (m, 2H, CH2CH2CHCH2), 2.37 (2 × s, 12H, CH3,tmcp), 2.85 (m, 2H, CH2,tmcp), 4.99 (m, 2H, CH2), 5.78 (m, 1H, −CH). 13C NMR: δ 28.6, 2 × 29.2, 33.3 (CH2CH2CH2CH2), 114.8 (CH2), 137.4, 138.1, 138.2 (Ctmcp), 141.9 (−CH). 6783
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Organometallics
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(neat, cm−1): 2946 (m), 2914 (vs), 2865 (m), 2850 (m), 1444 (vs), 1246 (m), 1063 (w), 1016 (w), 903 (w), 832 (s), 816 (vs), 789 (w). 4a. Obtained by an analogous procedure from 3a, yield 41%. 1 H NMR: δ −0.06 (s, 24H, Si1CH3), 0.46 (m, 8H, Si1CH2), 0.54 (m, 16H, SiCH2CH2CH2Si), 1.30 (m, 40H, SiCH2CH2CH2Si, Si1CH2CH2CH2CH2CH2), 2.06 (s, 48H, CH3,tmcp), 2.46 (m, 8H, CH2,tmcp), 6.26 (s, 20H, CHcp). 13C NMR: δ −3.3 (Si1CH3), 13.5 (CH3,tmcp), 17.5, 18.5, 20.3 (SiCH2CH2CH2Si), 15.4, 23.8, 28.7, 29.5, 29.6, 33.4 (Si1CH2CH2CH2CH2CH2CH2), 119.8 (CHcp), 129.3, 130.7, 134.1 (Ctmcp). 29Si NMR: δ 0.58 (Si0), 1.54 (Si1). HRMS (ESI): calcd for C100H164NaCl8Si5Ti4 ([M + Na]+), 1999.7003; found, 1999.7014. IR (neat, cm−1): 2936 (m), 2912 (vs), 2858 (m), 2850 (m), 1436 (vs), 1244 (m), 1057 (w), 1015 (w), 900 (w), 824 (s), 816 (vs), 784 (w). 5c. Obtained by an analogous procedure from 3c and Si[CH2CH2CH2SiMe(CH2CH2CH2SiMe2H)2]4, yield 24%. 1 H NMR: δ −0.06 (s, 12H, Si1CH3), −0.02 (s, 48H, Si2CH3), 0.58 (m, 64H, SiCH2CH2CH2Si, Si2CH2), 1.36 (m, 56H, SiCH2CH2CH2Si, Si2CH2CH2CH2), 2.07 (s, 48H, CH3,tmcp), 2.48 (m, 16H, CH2,tmcp), 6.28 (s, 20H, CHcp). 13C NMR: δ −3.3 (Si1CH3), 13.5 (CH3,tmcp), 17.5, 17.8, 18.5, 19.7, 20.2, 20.9 (SiCH2CH2CH2Si), 15.3, 24.5, 28.5, 33.5 (Si1CH2CH2CH2CH2), 119.8 (CHcp), 129.3, 130.7, 134.1 (Ctmcp). (3-Cyclopentadienylpropyl)dimethylsilane (6a,b). A solution of cyclopentadienylsodium in THF (17.3 mL, 34.6 mmol) was added dropwise to a solution of 3-iodopropyldimethylsilane (7.9 g, 34.6 mmol) in dry THF (20 cm3). After the addition, the reaction mixture was stirred for 12 h and the solvent was evaporated under vacuum. The residue was extracted repeatedly with dry pentane (3 × 15 mL) and filtered. The filtrate was evaporated under vacuum, and the crude product was purified by flash chromatography with CH3CN as the eluent, affording the required product as a mixture of two isomers. Yield: 3.72 g (22.5 mmol, 65%) of a colorless liquid. 1 H NMR: (CDCl3) δ 0.08 (d, J = 3.7 Hz, 12 H, SiMe2), 0.58−0.69 (m, 4 H, CH2SiMe2), 1.53−1.68 (m, 4 H, CH2CH2CH2), 2.34−2.51 (m, 4 H, CH2C5H4), 2.85−3.01 (m, 4 H, CH2-ring), 3.83−3.94 (m, 2 H, SiH), 5.98−6.07 (m, 1 H, CH-ring), 6.15−6.20 (m, 1 H, CH-ring), 6.24−6.30 (m, 1 H, CH-ring), 6.39−6.50 (m, 3 H, CH-ring). 13C{1H} NMR: (CDCl3) δ −4.47 (SiMe2), 14.05, 14.09, 23.08, 24.71, 33.31, 34.18 (SiCH2CH2CH2), 41.19, 43.16 (CH2-ring), 126.00, 126.44, 130.43, 132.42, 133.58, 134.73 (CH-ring), 147.07, 149.85 (C-ring). 29 Si{1H} NMR (CDCl3): δ −13.16. [(HMe2SiCH2CH2CH2C5H4)(C5H5)TiCl2] (7). A mixture of 6a and 6b (1.31 g, 7.86 mmol) was added dropwise to a vigorously stirred solution of n-BuLi (4.91 mL, 7.86 mmol) in 150 mL of hexane at −40 °C. After the addition the solution was slowly warmed to room temperature. The reaction mixture was further stirred for 3 h at room temperature; the solvent was then removed at reduced pressure and the residue washed with cold pentane. Filtration and evaporation gave a white solid (1.33 g, 7.7 mmol, 98%). The substituted lithium cyclopentadienide in THF (20 mL) was added dropwise at −78 °C to a solution of [(η5-C5H5)TiCl3] (1.72 g, 7.8 mmol) in THF (15 mL). After addition the cooling was removed and the mixture was stirred at room temperature for 20 h. The resulting THF solution was filtered and evaporated under vacuum to dryness. The crude red oil was dissolved in 10 mL of the pentane/CH2Cl2 (1/1) mixture . Solvents were partially evaporated, and 5 crystallized as a red solid (0.97 g, 61%) at −30 °C. Mp: 105 °C. IR (Nujol, cm−1): 3111 (s), 2109 (ν(Si−H), s), 1494 (m), 1249 (s), 1170 (w), 1050 (s), 1025 (s), 1016 (s), 970 (m), 888 (vs), 859 (s), 826 (vs), 776 (m), 741 (w), 682 (w), 612 (vw), 415 (w). 1 H NMR (CDCl3): δ 0.06 (d, J = 3.8 Hz, 6 H, SiMe2), 0.59−0.62 (m, 2 H, SiCH2), 1.55−1.67 (m, 2 H, CH2CH2CH2), 2.75 (t, J = 7.7 Hz, 2 H, CH2C5H4), 3.84 (sp, J = 3.8 Hz, 1 H, SiH), 6.36 (m, 2 H, C5H4), 6.43 (m, 2 H, C5H4), 6.55 (s, 5H, C5H5). 13C{1H} NMR (CDCl3): δ −4.52 (SiMe2), 14.15, 25.52, 34.46 (SiCH2CH2CH2), 115.89, 122.94, 139.01 (C5H4), 119.61 (C5H5). 29Si{1H} NMR (CDCl3): δ −13.12. HRMS (ESI): calcd for C15H22NaCl2Si48Ti ([M + Na]+), 371.0245; found, 371.0237. SiMe2(CH2CH2CH2SiMe2Vi)2 (8). Two drops of Karstedt’s catalyst solution were added to a solution of diallyldimethylsilane (1.00 g, 7 mmol) in hexane (2 mL). After the mixture was stirred for 10 min,
HSiMe2Cl (2.15 g, 23.0 mmol) was added and the mixture was refluxed for 3 h and then stirred at room temperature overnight. The solvent and the excess of silane were removed under reduced pressure to give 2.31 g (100%) of SiMe2(CH2CH2CH2SiMe2Cl)2. The solution of this compound in 5 mL of hexane was added dropwise at 0 °C to a solution of vinylmagnesium chloride in THF (14 mL, 22.3 mmol) further diluted by THF (30 mL). After the addition the reaction mixture was warmed to room temperature and stirred overnight. Finally it was refluxed for 2 h. The mixture was then cooled to room temperature and poured into ice-cold saturated aqueous NH4Cl. The aqueous layer was extracted twice with diethyl ether, and the combined organic layers were washed twice with water and once with saturated aqueous NaCl and dried over anhydrous MgSO4. The volatiles were removed on the rotary evaporator and finally under high vacuum. Yield: 2.1 g, 96% of a yellow oil. 1 H NMR (300 MHz, CDCl3): δ −0.06 (s, 6 H, Si0CH3), 0.05 (s, 12 H, Si1CH3), 0.51−0.59 (m, 4 H, Si0CH2), 0.58−0.66 (m, 4 H, CH2Si1), 1.25−1.41 (m, 4 H, Si0CH2CH2CH2), 5.66 (dd, 2J = 4.1, 3J = 20.0, 2 H, SiCHCHH-trans); 5.94 (dd, 2J = 4.1, 3J = 14.7, 2 H, SiCHCHH-cis), 6.15 (dd, 3J = 14.7, 3J = 20.0, 2 H, SiCHCH2). 13 C{1H} NMR (CDCl3): δ −3.3 (Si1CH3), −3.2 (Si0CH3), 18.3, 20.0, 20.1 (SiCH2CH2CH2Si), 131.2, 139.5 (Si1CHCH2). 29Si{1H} NMR (CDCl3): δ −6.39 (Si1), 1.04 (Si0). 9. The compound was synthesized according to the procedure for 8 from SiMe2(CH2CH2CH2SiMeCl2)2 (1.36 g, 3.67 mmol) and vinylmagnesium chloride solution (13.8 mL, 22.0 mmol). Yield: 1.12 g (91%) of a yellow oil. 1 H NMR (300 MHz, CDCl3): δ −0.07 (s, 6 H, Si0CH3), 0.13 (s, 6 H, Si1CH3), 0.50−0.60 (m, 4 H, Si0CH2), 0.66−0.75 (m, 4 H, CH2Si1), 1.28−1.43 (m, 4 H,, Si0CH2CH2CH2), 5.70 (dd, 2J = 4.4, 3J = 19,7; 4 H, SiCHCHH-trans), 6.0 (dd, 2J = 4.38, 3J = 14.71, 4 H, SiCHCHH-cis), 6.14 (dd, 3J = 14.71, 3J = 19.72, 4 H, SiCHCH2). 13 C{1H} NMR (CDCl3): δ −5.3 (Si1CH3), −3.2 (Si0CH3), 18.3, 20.0, 20.1 (SiCH2CH2CH2Si), 131.2, 139.5 (Si1CHCH2). 29Si{1H} NMR (CDCl3): δ −13.39 (Si1), 1.09 (Si0). 10. A solution of Si((CH2)3SiMe2Cl)4 (0.88 g, 1.54 mmol) in 5 mL of hexane was added dropwise at 0 °C to a solution of vinylmagnesium chloride in THF (5.8 mL, 9.2 mmol) further diluted by THF (20 mL). After the addition the reaction mixture was warmed to room temperature and stirred overnight. Finally it was refluxed for 2 h. The mixture was cooled to room temperature and then poured into ice-cold saturated aqueous NH4Cl. The aqueous layer was extracted twice with diethyl ether, and the combined organic layers were washed twice with water and once with saturated aqueous NaCl and dried over anhydrous MgSO4. The volatiles were removed on the rotary evaporator and finally under high vacuum. Yield: 0.70 g (87%) of a yellow oil. 1 H NMR (300 MHz, CDCl3): δ 0.05 (s, 24 H, Si1CH3), 0.50−0.58 (m, 8 H, Si0CH2), 0.55−0.67 (m, 8 H, CH2Si1), 1.25−1.39 (m, 8 H, Si0CH2CH2CH2), 5.66 (dd, J1 = 4.1 Hz, J2 = 20.0 Hz, 4 H, SiCHCHHtrans), 5.93 (dd, J1 = 4.1 Hz, J2 = 14.7 Hz, 4 H, SiCHCHH-cis), 6.14 (dd, J1 = 14.7 Hz, J2 = 20.0 Hz, 4 H, SiCHCH2). 13C{1H} NMR (CDCl3): δ −3.3 (Si1CH3), 17.4, 18.5, 20.3 (SiCH2CH2CH2Si), 131.2, 139.4 (Si1CHCH2). 29Si{1H} NMR (CDCl3): δ −6.45 (Si1), 0.72 (Si0). MS (MALDI): calcd for C28H60AgSi5 ([M + Ag]+), 643.26; found, 643.021. 11. Vinylation was carried out according to a procedure analogous to the preparation of 10. Yield: 1.15 g (79%) of a yellow oil. 1 H NMR (300 MHz, CDCl3): δ 0.12 (s, 12 H, Si1CH3), 0.50−0.58 (m, 8 H, Si0CH2), 0.66−0.70 (m, 8 H, CH2Si1), 1.25−1.40 (m, 8 H, Si0CH2CH2CH2), 5.66 (dd, 2J = 4.07, 3J = 20.03, 4 H, SiCHCHHtrans), 5.93 (dd, 2J = 4.07, 3J = 14.71, 4 H, SiCHCHH-cis), 6.14 (dd, 3 J = 14.71, 3J = 20.03, 4 H, SiCHCH2). 13C{1H} NMR (CDCl3): δ −5.2 (Si1CH3), 17.4, 18.4, 18.8 (SiCH2CH2CH2Si), 132.6, 137.2 (Si1CHCH2). 29Si{1H} NMR (CDCl3): δ −13.42 (Si1), 0.80 (Si0). MS (MALDI): calcd for C32H60AgSi5 ([M + Ag]+), 691.26; found, 691.009. 12. Vinylation was carried out according to a procedure analogous to the preparation of 10. Yield: 0.48 g (85%) of a yellow oil. 6784
dx.doi.org/10.1021/om300559y | Organometallics 2012, 31, 6779−6786
Organometallics
Article
H NMR (300 MHz, CDCl3): δ −0.08 (s, 12 H, Si1CH3), 0.05 (s, 48 H, Si2CH3), 0.50−0.57 (m, 32 H, Si1CH2, Si0CH2), 0.58−0.66 (m, 16 H, CH2Si2), 1.23−1.40 (m, 24 H, SiCH2CH2CH2), 5.66 (dd, 2J = 4.07, 2J = 20.0, 8H, SiCHCHH-trans), 5.93 (dd, 2J = 4.1, 2J = 14.7, 8H, SiCHCHH-cis), 6.14 (dd, 2J = 14.7, 2J = 20.0, 8H, SiCH CH2). 13C{1H} NMR (CDCl3): δ −5.0 (Si1CH3), −3.3 (Si0CH3), 17.7, 18.4, 18.6, 18.7, 19.2, 20.2 (SiCH2CH2CH2Si), 131.2, 139.4 (Si1CHCH2). 29Si{1H} NMR (CDCl3): δ −6.43 (Si2), 0.51 (Si0), 1.03 (Si1). MS (MALDI): calcd for C72H156AgSi13 ([M + Ag]+), 1491.83; found, 1491.818. 13. Vinylation was carried out according to a procedure analogous to the preparation of 10. Yield: 0.34 g (72%) of a yellow oil. 1 H NMR (300 MHz, CDCl3): δ −0.09 (s, 12 H, Si1CH3), 0.13 (s, 24 H, Si2CH3), 0.49−0.60 (m, 32 H, Si1CH2, Si0CH2), 0.66−0.75 (m, 16 H, CH2Si2), 1.21−1.43 (m, 24 H, SiCH2CH2CH2), 5.71 (dd, 2J = 4.4, 3J = 20.0, 16H, SiCHCHH-trans), 6.00 (dd, 2J = 4.4, 3J = 14.7, 16H, SiCHCHH-cis), 6.12 (dd, 3J = 14.7, 3J = 20.0, 16H, SiCH CH2). 13C{1H} NMR (CDCl3): δ −5.2 (Si1CH3), −5.0 (Si0CH3), 17.7, 18.6, 19.0, 18.3, 18.7, 18.7 (SiCH2CH2CH2Si), 132.6, 137.2 (Si1CHCH2). 29Si{1H} NMR (CDCl3): δ −13.42 (Si2), 0.55 (Si0), 1.08 (Si1). MS (MALDI): calcd for C80H156AgSi13 ([M + Ag]+), 1587.83; found, 1588.120. 14. A solution of the dendrimer SiMe2(CH2CH2CH2SiMe2Vi)2 (8; 38 mg, 0.121 mmol) in 0.5 mL of toluene was treated with 1 drop of Karstedt’s catalyst solution. Then solid complex 7 (100 mg, 0.29 mmol) was added. The mixture was stirred for 20 h at 70 °C. Volatiles were removed at reduced pressure, and the crude product was purified by GPC chromatography with chloroform as the eluent. Yield: 0.089 g (65%) of a red oil. 1 H NMR (CDCl3): δ −0.06 (s, 6 H, Si0CH3), −0.05 (s, 24 H, 1,2 Si CH3), 0.34 (bs, 8 H, SiCH2CH2Si), 0.50−0.58 (m, 12 H, SiCH2CH2CH2Si, Si2CH2), 1.22−1.36 (m, 4 H, SiCH2CH2CH2Si), 1.49−1.69 (m, 4 H, CH2CH2C5H4), 2.73 (t, 3J = 7.8 Hz, 4H, CH2C5H4), 6.37 (pt, 4 H, C5H4), 6.44 (pt, 4 H, C5H4), 6.55 (s, 10 H, C5H5). 13C{1H} NMR (CDCl3): δ −3.98 (Si1CH3), −3.81(Si2CH3), −3.17 (Si0CH3), 7.08, 7.22 (SiCH2CH2Si), 18.36, 19.34, 20.05 (SiCH2CH2CH2Si), 14.77, 25.23, 34.95 (Si2CH2CH2CH2), 116.04, 122.91, 139.03 (C5H4) 119.59 (C5H5). 29Si{1H} NMR (CDCl3): δ 0.98 (Si 0 ), 3.34 (Si 1 ), 3.97 (Si2 ). HRMS (ESI): calcd for C46H80NaSi5Cl4Ti2 ([M + Na]+), 1031.2717; found, 1031.2726. 15. A solution of SiMe2(CH2CH2CH2SiMeVi2)2 (9; 18 mg, 0.054 mmol) in 0.5 mL of toluene was treated with 1 drop of Karstedt’s catalyst solution. Then solid complex 7 (90 mg, 0.26 mmol) was added. The mixture was stirred for 45 h at 80 °C. Volatiles were removed at reduced pressure, and the crude product was purified by GPC chromatography with chloroform as the eluent. Yield: 0.053 g (58%) of a red oil. 1H NMR (CDCl3): δ −0.11 (s, 6 H, Si1CH3), −0.05 (s, 30 H, Si0,2CH3), 0.32 (bs, 16 H, SiCH2CH2Si), 0.47−0.58 (m, 16 H, SiCH 2CH2 CH2 Si, Si2CH 2), 1.20−1.34 (m, 8 H, SiCH2CH2CH2Si), 1.49−1.69 (m, 4 H, CH2CH2C5H4), 2.73 (t, 3J = 7.8 Hz, 8H, CH2C5H4), 6.37 (pt, 8 H, C5H4), 6.44 (pt, 8 H, C5H4), 6.55 (s, 20 H, C5H5). 13C{1H} NMR (CDCl3): δ −6.0 (Si1CH3), −3.9 (Si0CH3), −3.1 (Si2CH3), 5.1, 7.2 (SiCH2CH2Si), 14.8, 17.5, 18.4, 20.2, 25.3, 35.0 (SiCH2CH2CH2Si), 116.0, 123.1, 139.1 (C5H4), 119.6 (C5H5). 29Si{1H} NMR (CDCl3): δ 0.96 (Si0), 3.95 (Si2), 5.60 (Si1). 16. A procedure analogous to that used for the synthesis of 14 was followed, starting from 0.032 g (0.060 mmol) of vinylated dendrimer 10 and 0.10 g (0.29 mmol) of complex 7. Yield: 0.072 g, 62% of a red solid. 1 H NMR (CDCl3): δ −0.07 (s, 24 H, Si2Me2), −0.06 (s, 24 H, Si1Me2), 0.33 (bs, 16 H, SiCH2CH2Si), 0.49−0.58 (m, 24 H, SiCH2CH2CH2Si, Si2CH2), 1.23−1.36 (m, 8 H, SiCH2CH2CH2Si), 1.49−1.61 (m, 8 H, CH2CH2C5H4), 2.72 (t, 3J = 7.5 Hz, 8H, CH2C5H4), 6.36 (pt, 8 H, C5H4), 6.43 (pt, 8 H, C5H4), 6.55 (s, 20 H, C5H5). 13C{1H} NMR (CDCl3): δ −3.93 (Si1Me2), −3.76 (Si2Me2), 7.12, 7.34 (SiCH2CH2Si), 17.51, 18.56, 19.67 (SiCH2CH2CH2Si), 14.82, 25.25, 35.02 (Si2CH2CH2CH2), 116.04, 122.96, 139.07 (C5H4), 119.62 (C5H5). 29Si{1H} NMR (CDCl3): δ 0.64 (Si0), 3.27 (Si1), 3.94 (Si2). HRMS (ESI): calcd for C88H148NaSi9Cl848Ti4 ([M + Na]+), 1951.4828; found, 1951.4821. IR (neat, cm−1): 3108 (m), 2950 (s), 1
2909 (vs), 2873 (s), 1489 (w), 1441 (m), 1404 (w), 1247 (vs), 1131 (m), 1050 (m), 906 (w), 826 (vs), 781 (m), 704 (w). 17. A procedure analogous to that used for the synthesis of 15 was followed, starting from 0.016 g (0.027 mmol) of vinylated dendrimer 11 and 0.09 g (0.26 mmol) of complex 7. Yield: 0.050 g, 55% of a red solid. 1 H NMR (300 MHz, CDCl3): δ −0.11 (s, 12 H, Si1CH3), −0.06 (s, 48 H, Si2CH3), 0.32 (bs, 32 H, SiCH2CH2Si), 0.49−0.58 (m, 32 H, SiCH2CH2CH2Si, Si2CH2), 1.22−1.35 (m, 8 H, SiCH2CH2CH2Si), 1.48−1.62 (m, 16 H, CH2CH2C5H4), 2.73 (t, 3J = 7.5 Hz, 16H, CH2C5H4), 6.36 (pt, 16 H, C5H4), 6.44 (pt, 16 H, C5H4), 6.56 (s, 40 H, C5H5).). 13C{1H} NMR (CDCl3): δ −5.92 (Si1CH3), −3.85 (Si2CH3), 5.15, 7.18 (SiCH2CH2Si), 17.60, 17.84, 18.56, 14.84, 25.28, 35.04 (SiCH2CH2CH2Si), 115.94, 123.14, 139.05 (C5H4), 119.69 (C5H5). 29Si{1H} NMR (CDCl3): δ 0.64 (Si0), 5.59 (Si1), 3.93 (Si2). 18. A procedure analogous to that used for synthesis of 14 was followed, starting from 0.033 g (0.024 mmol) of vinylated dendrimer 12 and 0.08 g (0.23 mmol) of complex 7. Yield: 0.056 g, 56% of a red solid. 1 H NMR (300 MHz, CDCl3): δ −0.08 (s, 12 H, Si1CH3), −0.07 (s, 48 H, Si2CH3), −0.06 (s, 48 H, Si3CH3), 0.32−0.35 (m, 32 H, SiCH2CH2Si), 0.50−0.59 (m, 64 H, SiCH2CH2CH2Si, Si3CH2), 1.25− 1.35 (m, 24 H, SiCH 2 CH 2 CH 2 Si), 1.51−1.60 (m, 16 H, CH2CH2C5H4), 2.72 (t, 3J = 7.5 Hz, 16H, CH2C5H4), 6.36 (pt, 16 H, C5H4), 6.43 (pt, 16 H, C5H4), 6.55 (s, 40 H, C5H5). 13C{1H} NMR (CDCl3): δ −4.9 (Si1CH3), −3.9 (Si2CH3), −3.7 (Si3CH3), 7.1, 7.3 (SiCH2CH2Si), 17.7, 18.5, 18.6, 18.8, 19.2, 19.5 (SiCH2CH2CH2Si), 14.8, 25.3, 35.0 (Si3CH2CH2CH2), 116.1, 123.0, 139.1 (C5H4), 119.6 (C5H5). 29Si{1H} NMR (CDCl3): δ 0.50 (Si0), 0.97 (Si1), 3.31 (Si2), 3.95 (Si3). IR (neat, cm−1): 3107 (m), 2949 (s), 2908 (vs), 2870 (s), 1445 (m), 1246 (s), 1139 (m), 1054 (m), 906 (w), 824 (vs), 704 (w). 19. A procedure analogous to that used for synthesis of 15 was followed, starting from 0.017 g (0.012 mmol) of vinylated dendrimer 13 and 0.08 g (0.23 mmol) of complex 7. Yield: 0.043 g, 51% of a red solid. 1 H NMR (300 MHz, CDCl3): δ −0.11 (s, 12 H, Si1CH3), −0.09 (s, 24 H, Si2CH3), −0.06 (s, 96 H, Si3CH3), 0.32 (bs, 64 H, SiCH2CH2Si), 0.50−0.57 (m, 80 H, SiCH2CH2CH2Si, Si3CH2), 1.24−1.31 (m, 24 H, SiCH2CH2CH2Si), 1.51−1.59 (m, 32 H, CH2CH2C5H4), 2.73 (t, 3J = 7.7 Hz, 32H, CH2C5H4), 6.36 (pt, 32 H, C5H4), 6.45 (pt, 32 H, C5H4), 6.56 (s, 80 H, C5H5). 13C{1H} NMR (CDCl3): δ −5.9 (Si2CH3), −4.9 (Si1CH3), −3.8 (Si3CH3), 5.1, 7.2 (SiCH2CH2Si), 17.7, 18.3, 18.5, 18.9, 19.2, 23.4 (SiCH2CH2CH2Si), 14.9, 25.3, 35.0 (Si3CH2CH2CH2), 116.0, 123.2, 139.1 (C5H4), 119.6 (C5H5). 29Si{1H} NMR (CDCl3): δ 0.40 (Si0), 0.97 (Si1), 3.94 (Si3), 5.58 (Si2). IR (neat, cm−1): 3108 (m), 2945 (s), 2907 (vs), 2868 (s), 1497 (w), 1436 (m), 1246 (s), 1132 (m), 1055 (m), 1026 (w), 908 (w), 824 (vs).
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ASSOCIATED CONTENT
* Supporting Information S
Figures giving MALDI-TOF mass spectra of vinyl-terminated dendrimers 10−13, ESI-TOF mass spectra of titanocene dichloride decorated dendrimers 4a, 14, and 16, and NMR spectra of dendrimers and wedges 4a,b, 8−13, and 15−19. This material is available free of charge via the Internet at http:// pubs.acs.org.
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AUTHOR INFORMATION
Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This work was supported by the Ministry of Education, Youth and Sport of the Czech Republic (Grant No. LC06070). Partial support (to T.S. and J.Č .) from the UniCRE project (CZ.1.05/ 2.1.00/03.0071) is also appreciated. Financial support by the 6785
dx.doi.org/10.1021/om300559y | Organometallics 2012, 31, 6779−6786
Organometallics
Article
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CNRS, Conseil Regional Champagne Ardenne, Ministry of Higher Education and Research (MESR), and EU-programme FEDER to the PlAneT CPER project is gratefully acknowledged.
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dx.doi.org/10.1021/om300559y | Organometallics 2012, 31, 6779−6786
