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Aromatic carbonyl compounds such as aromatic aldehydes and ketones [R1R2C O: R1 = H; R2 = Ph (1a), 2,4-Cl2Ph (1b), 2,4-Me2Ph (1c): R1 = Ph; R2 = Ph (1d), 4-ClPh (1e), 4-MePh (2f), 2,4-Me2Ph (1g) undergo the deoxygenative silylation with HSiCl3 in the presence of Bu4PCl at 150 °C within 1.0–1.5 h to give arylmethyltrichlorosilanes 2 (R1R2CH–SiCl3) in high yields (85–95%). The reactivity of aromatic carbonyl compounds decreases with increasing the electron withdrawing ability of substituent(s) on the benzene-ring. A highly efficient synthetic route to arylmethyltrichlorosilanes has been developed starting from aromatic aldehydes and ketones in this study.

New charged cyclometalated iridium(III) complexes [Ir(ppy)2(L)](PF6) [ppy = 2-phenylpyridine; L = bis(pyrazol-1-yl)methane (for 1); L = bis(3,5-dimethylpyrazol-1-yl)methane (for 2)] were synthesized and their electrochemical and photophysical properties studied. These complexes with non-p-electron-conjugated ancillary chelates exhibit significantly blueshifted emission relative to those of commonly used derivatives with NN ancillary ligands such as bipyridine or phenanthroline. Both X-ray and theoretical analysis based on time-dependent density functional theory (TD-DFT) reveal that the binding of Ir to the bis(pyrazol-1-yl)methane ancillary ligand is much weaker than that to the phenylpyridine main ligand; the effect is enhanced in the excited state. As a result, the ancillary ligand does not participate in low-energy excitations and triplet emission, and the electronic transitions are concentrated on the main chromophoric ligands. The blueshift feature is attributed to emission originating from the main cyclometalated ligands, in contrast to emitters with the NN chromophoric ancillary ligand. In addition, complex 2 exhibits a one order of magnitude higher non-radiative decay rate than complex 1, which is attributed to the steric hindrance of the methyl groups that leads to a more loosely bound ancillary ligand.

[Bu4P]+Cl−-catalyzed reactions of trichlorosilane and dichloromethylsilane with vinyltrichlorosilane gave 1,1,4,4-tetrachloro-2,5-bis(trichlorosilyl)-1,4-disilacyclohexane (1) and 1,1,4,4-tetrachloro-2,5-bis(methyldichlorosilyl)-1,4-disilacyclohexane (4), respectively.

Cyclic and linear carbosilanes, (Cl2SiCH2)2 (2) and Cl2Si(CH2SiCl3)2 (3), were produced from phosphine-catalized Si−C coupling reactions of bissilylmethanes, HCl2SiCH2SiX1X2Cl (X1, X2 = Cl (1), X1 ...

Amphiphilic ligands 4′-((4-(5-pyridin-4-yloxy)pentyloxy)styryl)-4-methyl-2,2′-bipyridine (L1), 4,4′-bis((E)-4-(5-(pyridin-4-yloxy)pentyloxy)styryl)-2,2′-bipyridine (L2), 4′-(4-(5-(4′-cyano-4-biphenoxy)pentyloxy)styryl)-4-methyl-2,2′-bipyridine (L3), and 4′-(4-(5-(zinc tetrakis-5,10,15-tritolyl-20-(4-hydroxyphenyl)porphyrin)pentyloxy)styryl)-4-methyl-2,2′-bipyridine (L4) and their heteroleptic ruthenium(II) complexes of the types [Ru(L1)(L)(NCS)2] (D20), [Ru(L2)(L)(NCS)2] (D21), [Ru(L3)(L)(NCS)2] (D22), and [Ru(L4)(L)(NCS)2] (D23) (where L = 4,4′-bis(carboxylic acid)-2,2′-bipyridine) have been synthesized, as photosensitizers for nanocrystalline dye-sensitized solar cells. All complexes D20–D23 exhibit a broad MLCT band around 520–530 nm in DMF and an emission band around 740–790 nm in DMF. We have studied photovoltaic performances based on the newly synthesized dyes. Under standard AM 1.5 sunlight, the dye D20 gave a short-circuit photocurrent density of 13.31 mA/cm2, an open-circuit voltage of 0.64 V, and a fill factor of 0.68, corresponding to an overall conversion efficiency of 5.81%.

New organic dyes composed of the benzo[b]furan donor, thiophene-conjugated bridge, and cyano acrylic acid acceptor have been newly synthesized through the one-pot coupling cyclization key step. Nanocrystalline TiO2 dye-sensitized solar cell was fabricated using this dye. A solar-to-electric conversion efficiency of 6.65% and 4.70% is achieved with 1 and 2, respectively.

Preparation of a triisocyanide ligand, 1,3,5-tris[(4-isocyano-3,5-diisoproyl-phenyl)ethynyl]benzene (5), is presented. Ligand 5 is obtained in three steps in 76% overall yield. Reaction of 5 with (eta5-Cp*)Rh(Cabs,s')(Cabs,s'= 1,2-S2C2B10H10-S,S') produced the rhodadithiolene adduct [[(eta5-Cp*)Rh(Cabs,s')(CNC6H2iPr2-2,6-CC-3)]3C6H3-1,3,5] (6). Ligand 5 reacts with Cr(CO)5(THF) to give the triisocyanide complex [[Cr(CO)5(CNC6H2iPr2-2,6-CC-3)]3C6H3-1,3,5] (8) and with [AuCl(SMe2)] to give the triisocyanide complex [[AuCl(CNC6H2iPr2-2,6-CC-3)]3C6H3-1,3,5] (9). As revealed by a single-crystal X-ray diffraction study, the C(9)-N(3)-C(61) angle of 5.9 degrees of trichromium complex 8 occurs in the plane of the bridge and the gold center has a slightly bent linear configuration with a Cl(1)-Au(1)-C(21) angle of 175.4(4) degrees . The rhenation and platination of 5 employing [Re(bpy)(CO)3(AN)]PF6 (AN= acetonitrile) and [(CwedgeNwedgeN)PtCl] ((HCwedgeNwedgeN)= 6-phenyl-2,2'-bipyridine) yielded the luminescent Re(I) and Pt(II) complexes. Full characterization includes structural study of complexes 2, 8, and 9.

Rigid spacer-chelator with the framework of 3 has been prepared. Building units with two parallel coordination sites such as salen and oxazoline units have also been synthesized. The spacer-chelators, 11 and 15 , readily self-assembled with metal complexes such as Zn ++ and Co ++ to form molecular rectangles. The overall dimensions of the rectangles, 13 and 17 , are 6.2 A × 23.5 A. The characterization of the supramolecules by NMR, mass spectroscopy, and X-ray crystal structures is also reported.

Two diarylethene trimers bridged by ethenyl and ethynyl groups were synthesized and their photochromic behaviors were examined. Upon irradiation of the trimers 2 and 4 with UV light, one–three photoinduced cyclization reactions occur. Each isomer was isolated and analyzed by 1H NMR spectrum. The quantum yield of 2 and 4 is 0.52 and 0.311, respectively.

A novel series of blue emitting silylene-spaced diphenylanthracene derivatives have been synthesized and characterized. The rhodium-catalyzed hydrosilylation of bis[4-(dimethylsilyl)phenyl]anthracene 3–4 yielded stable 9,10-disubstituted (E)-divinylsilylene–diphenylanthracene products 7–10 and salt elimination reaction of bis[4-(chlorodimethylsilyl)phenyl]anthracene 5–6 gave 9,10-disubstituted disilyldiphenylanthracene compounds 11–14. They are fluorescent in the blue region with good quantum efficiencies. The rhodium-catalyzed polyaddition including 2-tert-butyl-9,10-bis[4-(dimethylsilyl)phenyl]anthracene (4) afforded the nonconjugated copolymer 15.

Bis(dichlorosilyl)methanes 1 undergo the two kind reactions of a double hydrosilylation and a dehydrogenative double silylation with alkynes 2 such as acetylene and activated phenyl-substituted acetylenes in the presence of Speier’s catalyst to give 1,1,3,3-tetrachloro-1,3-disilacyclopentanes 3 and 1,1,3,3-tetrachloro-1,3-disilacyclopent-4-enes 4 as cyclic products, respectively, depending upon the molecular structures of both bis(dichlorosilyl)methanes (1) and alkynes (2). Simple bis(dichlorosilyl)methane (1a) reacted with alkynes [R1–C C–R2: R1 = H, R2 = H (2a), Ph (2b); R1 = R2 = Ph (2c)] at 80 °C to afford 1,1,3,3-tetrachloro-1,3-disilacyclopentanes 3 as the double hydrosilylation products in fair to good yields (33–84%). Among these reactions, the reaction with 2c gave a trans-4,5-diphenyl-1,1,3,3-tetrachloro-1,3-disilacyclopentane 3ac in the highest yield (84%). When a variety of bis(dichlorosilyl)(silyl)methanes [(MenCl3 − nSi)CH(SiHCl2)2: n = 0 (1b), 1 (1c), 2 (1d), 3 (1e)] were applied in the reaction with alkyne (2c) under the same reaction conditions. The double hydrosilylation products, 2-silyl-1,1,3,3-tetrachloro-1,3-disilacyclopentanes (3), were obtained in fair to excellent yields (38–98%). The yields of compound 3 deceased as follows: n = 1 > 2 > 3 > 0. The reaction of alkynes (2a–c) with 1c under the same conditions gave one of two type products of 1,1,3,3-tetrachloro-1,3-disilacyclopentanes 3 and 1,1,3,3-tetrachloro-1,3-disilacyclopent-4-enes (4): simple alkyne 2a and terminal 2b gave the latter products 4ca and 4cb in 91% and 57% yields, respectively, while internal alkyne 2c afforded the former cyclic products 3cc with trans form between two phenyl groups at the 3- and 4-carbon atoms in 98% yield, respectively. Among platinum compounds such as Speier’s catalyst, PtCl2(PEt3)2, Pt(PPh3)2(C2H4), Pt(PPh3)4, Pt[ViMeSiO]4, and Pt/C, Speier’s catalyst was the best catalyst for such silylation reactions.

Two macrocycles bearing four dithienylethene units were synthesized. Upon irradiation of the macrocycles 5 and 6 with ultraviolet light, only one or two photo-induced cyclization reaction occurs. Each isomers were isolated and analyzed by 1 H NMR spectrum. The quantum yield of 5 and 6 are 0.58 and 0.64, respectively. The high value is due to the presence of enforced antiparallel conformation in the macrocycles 5 and 6 .

The facile hydrostannation of diynes and triynes with tributyltin hydride was achieved. The hydrostannation product readily underwent the Stille cross-coupling reaction with a variety of aryl bromides. The copper-mediatedStille cross-coupling of 1,3,5-tris[(E)-2-(tributylstannyl)vinyl]benzene with (E)-β-iodostyrene afforded the conjugated diene.

Reaction of (triphenylmethyl)silanetriol (1) with cyclopentadienyltitanium trichloride (CpTiCl3) in the presence of triethylamine as a HCl scavenger gave both compounds of a partial open-cage type {[Ph3CSiO(OH)]3(Ph3CSiO3/2)(CpTiO3/2)4} (2) and cube type (Ph3CSiO3/2CpTiO3/2)4 (3). The 1:1 reaction of 1 and CpTiCl3 in toluene solvent at reflux temperature for 3 d afforded compounds 2 (22%) and 3 (36%). When 1 is reacted with a 1.5 fold excess of CpTiCl3 under the same conditions, compound 3 was obtained in high yield (81%) along with 2 in trace quantities. Compounds 2 and 3 were fully characterized by the analyses of 1H, 13C, 29Si NMR, IR, and FAB MS data. The solid-state structure of 3 was determined by a single crystal X-ray diffraction study. Compound 3 had shown to have catalytic activity for the oxidation of alkenes such as 1-octene, cyclooctene, and norbornene with t-butyl hydrogen peroxide. The effect of solvent was observed in this epoxidation reaction. The order of reactivity were decreased as follows: CHCl3 > hexane ≫ THF.

A new family of dithienosiloles that contain two peripheral triarylamine moieties have been synthesized for use in organic light-emitting devices (OLEDs). The compounds are strongly fluorescent. We studied EL (electroluminescent) properties of these compound in multilayer EL devices having the following structure: ITO/TPD/compound 2b−5b/BCP/Alq3/Al:Li (ITO = indium tin oxide; TPD = 1,4-bis(phenyl-m-tolylamino)biphenyl; BCP = 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; Alq3 = tris(8-hydroxyquinolinolato)aluminum (III)). Among the devices, green light-emitting device ITO/TPD/2b/BCP/Alq3/Al:Li exhibits the highest EL performance.

The Rh(I)-catalyzed hydroboration of a variety of aromatic diynes and a triyne afforded bis(boryl)- and tris(boryl)vinyl products. The hydroboration products underwent Suzuki cross-coupling reactions with a variety of substrates containing chromophore units to give fluorescent dye-substituted products. The hydroboration product also reacted with dibromoarenes to afford an oligomer with a vinylene unit along the oligomer backbone.

A variety of diyne and triyne π-electron bridges were hydrosilylated to afford the bis- and tris(silylvinyl) π-electron bridges. The hydrosilylation products underwent substitution reactions with a variety of compounds containing chromophore units to give fluorescent dye substituted products. The easy access of the silyl hydrides may be applied to construct a large number of copolymers.

The dehydrochlorinative Si−C coupling reactions of various primary and secondary alkyl chlorides with hydridochlorosilanes in the presence of tetrabutylphosphonium chloride as catalyst gave the coupling products with elimination of HCl as a gas. Coupling reactions of activated alkyl chlorides such as benzyl chlorides proceeded at 130 °C, while unactivated organic chlorides such as silylalkyl chlorides and secondary alkyl chlorides required higher reaction temperatures of 150 or 170 °C and longer reaction times. Primary alkyl chlorides reacted with trichlorosilane (1) to give coupling products in good to excellent yields, but secondary alkyl chlorides reacted at a slower rate and gave lower yields of products. Coupling reactions with methyldichlorosilane instead of 1 proceeded at slower rates and gave lower yields of products.

Department of Chemistry, Graduate School, Yonsei University, Seoul 120-749, KoreaReceived May 8, 2002Friedel-Crafts alkylation reaction of an isomeric mixture of 1,2,3,4,5,6,7,8- (2) and 1,2,3,4,5,6,7,8-octahydrophenanthrene (2') with excess vinylchlorosilanes such as vinyl(methyl)dichlorosilane (1a) andvinyltrichlorosilane (1b) in the presence of aluminum chloride catalyst at 80

Friedel−Crafts alkylation reactions of biphenyl with (dichloroalkyl)chlorosilanes [Cl3-mMemSi(CnH2n-1Cl2), m = 0−2, n = 1−3] at temperatures ranging from 120 to 160 °C in the presence of a Lewis ac...

The reaction of the 1,2-dilithiated o-carborane with 1,2-dichlorotetraethyldisilane yielded the strained 3,4-carboranylene-1,1,2,2-tetraethyl-1,2-disilacyclobut-3-ene (2), which was found to be a good reactant for the double-silylation reaction. Thus, the reaction of 2 with RC⋮CR‘ in the presence of a catalytic amount of Pd(PPh3)4 yielded the six-membered disilyl ring compounds B10H10C2(SiEt2)2(RCCR‘) (R = Ph, R‘ = H (6); R = Ph, R‘ = CH3 (7); R = R‘ = COOCH3 (8); R = C4H9, R‘ = H (9)). The palladium-catalyzed reaction of 2 with 4-nitrobenzaldehyde afforded 5,6-carboranylene-2-oxa-1,4-disilacyclohex-5-ene (10). In contrast, the reaction of 2 with trans-cinnamaldehyde under the same reaction conditions yielded the insertion compound 11 formed via insertion of a carbonyl group into each of the C−Si bonds of 2. The structures of compounds 2, 6, and 11 were determined by single-crystal X-ray crystallography.

(Polychloromethyl)silanes (Cl 3− m Me m SiCH 3− n Cl n : m =0–3; n =2, 3) reacted with excess benzene in the presence of aluminum chloride to give (polyphenylmethyl)silanes. Such reactions occurred at the temperatures ranging from room temperature ( m =2, 3; n =2) to 80°C ( m =0, 1; n =2, 3), indicating that the reactivity increases with increasing the number (m) of electron-donating methyl-group(s) at the silicon. In particular, (dichloromethyl)silanes with two or three methyl groups at the silicon ( m =2 or 3; n =2) underwent the alkylation and the decomposition of their products at room temperature. The reaction with (dichloromethyl)trimethylsilane occurred immediately at room temperature to give no (diphenylmethyl)trimethylsilane, but diphenylmethane and trimethylchlorosilane via the decomposition of alkylation product. (Trichloromethyl)silanes ( m =0, 1; n =3) reacted with excess benzene to give (triphenylmethyl)silanes as major products and the unusual (diphenylmethyl)silanes as minor. It was found that unusual (diphenylmethyl)silanes were formed by the decomposition of (triphenylmethyl)silanes under the reaction condition. In the alkylation to benzene, the reactivity of (polychloromethyl)silanes (Cl 3− m Me m SiCH 3− n Cl n : m =0–3; n =2, 3) decreases in the following order: m =3>2>1>0; n =3>2.

The chemistry of titanium complexes stabilized by a series of cyclic silyldiamide ligands(cycl)Si(HNBut)2 (2) derived from the silacycloalkyl unit -(CH2)nSi-, with n = 3, 4, and 5, has been studied. Thus, a variety of spiro-siladiazatitanacyclobutane complexes (cycl)Si(NBut)2TiCl2 (3) has been prepared by the reaction of the dilithium salt of 2 with titanium tetrachloride. The reaction of 2 with Ti(NMe2)4 in refluxing toluene yields (cycl)Si(NBut)2Ti(NMe2)2 (4), and the product 4 is converted to 3 in a moderate isolated yield by treatment with excess Me3SiCl. Dimethyl complexes of the type (cycl)Si(NBut)2TiMe2 (5) were prepared by the reaction of 3 with MeMgBr. Complexes 3 have been characterized by X-ray crystallography. As a result of the formation of the siladiazatitanacyclobutane ring, the titanium atoms in 3 exhibit distorted-tetrahedral configurations with the two chloride ligands. In addition, the crystallographic results establish that steric interactions between the silacycloalkyl and tert-butyl ...

The (triphenylmethyl)silanetriol (1) was obtained in good yield by the hydrolysis of (triphenylmethyl)trichlorosilane, prepared by the Friedel-Crafts alkylation of benzene with (trichloromethyl)tri...

The structure-reactivity relationship of titanium complexes CySi(HNBut)2TiCl2 (1) (CySi = silacyclobutane, silacyclopentane, silacyclopentene, and silacyclohexane) stabilized by a series of cyclic silyldiamide ligands has been studied. The crystallographic results establish that steric interactions between the silacycloalkyl and tert-butyl groups influence the C(But)-N-Ti angles and, hence, the steric environment at titanium. The compounds 1 were further investigated as potential catalysts for the polymerization of ethylene. While sterically less demanding silacyclobutyl and -pentyl diamide complexes (1a and 1b) exhibit low ethylene polymerization activity (3.9 ∼5.8 kg PE molcat −1h−1) in the presence of methylalumoxane, highly puckered silacyclohexyl diamide complex 1e shows better activity (10 kg PE molcat −1 h−1) for the ethylene polymerization when it is activated with MAO.

(ω-Chloroalkyl)silanes [Cl 3− m Me m Si(CH 2 ) n Cl: m =0–3, n =1–3] underwent Friedel–Crafts alkylation with benzene in the presence of aluminum chloride to give alkylated products. Such alkylation reactions took place at temperatures ranging from room temperature ( m =0–1, n =2, 3; m =3, n =1) to 80 ( m =1, 2; n =1) and 200°C ( m =0; n =1), depending on the substituent(s) of the silicon and the alkylene-chain spacer between the silicon and CCl bond of (ω-chloroalkyl)silanes. In the alkylation to benzene, the reactivities of (ω-chloroalkyl)silanes increase as the number ( m ) of methyl-group(s) at the silicon and the alkylene length between the silicon and CCl bond increases. While decomposition of alkylation products was observed at two more methyl groups substituted at silicon in the cases of (chloromethyl)silanes such as (chloromethyl)dimethylchlorosilane and (chloromethyl)trimethylsilane. The reaction with (chloromethyl)trimethylsilane occurred at room temperature to give trimethylchlorosilane, toluene and xylene via a decomposition reaction of the products. No (trimethylsilylmethyl)benzene was formed. In the alkylation to benzene, the reactivity of (ω-chloroalkyl)silanes decreases in the following order: m =3>2>1>0; n =3>2≫1. The results are consistent with the stability of the carbocation generated by the complexation of (ω-chloroalkyl)silanes with aluminum chloride.

Friedel−Crafts alkylations of ferrocene, 1, with allylchlorosilanes in the presence of Lewis acid catalysts under mild conditions gave regiospecific [1-methyl-2-(alkylchlorosilyl)ethyl]ferrocenes in fair to good yields depending upon the substituents on silicon, along with small amounts of dialkylated products. The alkylation of ferrocene with 1.2 equiv of (2-methylallyl)dimethylchlorosilane, 2b, at 0 °C gave monoalkylated ferrocene 3b and an isomeric mixture of dialkylated products in 76% and 4% yields, respectively. The yield of the dialkylated ferrocene mixture increased to 21% when 2 equiv of alkylating agent 2b was used. The two components of the dialkylated product mixture were identified as 1,1‘-dialkylated ferrocene 4b (17%), and 1,3-dialkylated ferrocene 4b‘ (4%). A higher yield of the 1,1‘-diadduct compared to the 1,3-diadduct indicates that the electron-donating alkylsilyl group does not greatly enhance a second alkylation on the same ring. The reactivities of allylchlorosilanes in the ferrocen...

A highly efficient heteroleptic ruthenium (II) complex cis-di(thiocyanato)(4,4′-dicarboxylic acid-2,2′-bipyridine)(4,4′-di-(2-(4-ditolylamine phenyl)ethenyl)-2,2′-bipyridine) ruthenium (II) (IJ-1) was synthesized and characterized, which when anchored on nanocrystalline TiO2 films exhibited high power conversion efficiency, 10.3%, and incident photon to electron conversion efficiency, 87%.

The hydrosilylation of cyclic alkenes and linear alkenes with trialkylsilanes in the presence of Lewis acid catalysts under mild conditions gave the corresponding (trialkylsilyl)alkanes in fair to good yields. The reaction of 1-methylcyclohexene with triethylsilane at −20 °C gave cis-1-triethylsilyl-2-methylcyclohexane with regio- and stereoselectivity via a trans hydrosilylation pathway. Cycloalkenes having an alkyl group at the double-bonded carbon showed better reactivity than nonsubstituted compounds in the Lewis acid-catalyzed hydrosilylation. The catalytic reactivity of Lewis acids decreases in the following order: AlBr3 > AlCl3 > HfCl4 > EtAlCl2 > ZrCl4 > TiCl4. When triorganochlorosilane was used as an activator in the aluminum chloride-catalyzed reaction, the hydrosilylation rate drastically increased. The results are consistent with a stepwise mechanism proceeding via the formation of a trialkylsilylenium ion intermediate.

Linear 4-alkyl-5-silyl-1-alkenes 1a−c react with allylsilanes 2a,b in the presence of aluminum chloride catalyst at 40 °C to give unusual allylsilylation products 3a−d derived from an intramolecular silyl group rearrangement in 23−57% yield. The reaction of cyclic 1-allyl-2-(trimethylsilyl)cycloalkanes 1d,e with 2 gave the silyl-rearranged isomers of 1 in addition to the allylsilylation products 3e,f. The results are consistent with silylenium ion formation and a 1,5-hydride shift in the allylsilylation and isomerization.

The reaction of bis(chloromethyl)diorganosilanes (R2Si(CH2Cl)2: 1a, R = Me; 1b, R = allyl; 1c, R = benzyl; 1d, R = Ph) with magnesium gives 2a−d (65−90%) of formula MeR2SiCH2(SiR2CH2CH2)nH (n = 1, 2, 3, ...) and dimethyldiorganosilanes 3a−d (17−9%). The trapping reaction of the intermediates generated in the reaction of 1d with magnesium using CD3OD gives the corresponding CD3OD-trapped product of the 1,1-diphenylsilacyclopropane intermediate, Ph2Si(OCD3)(CH2CH2D) (6‘), along with the deuterated products of Ph2Si(CH2D)(CH2Cl) (5‘), Ph2Si(CH2D)2 (3d‘), and 2d‘. The results are consistent with a reaction course in which silacyclopropane intermediates are generated in the reaction of 1a−d with magnesium and then polymerized to 2a−d.

A series of 1-aryl-1-(1H-1,2,4-triazol-1-yl)alkyl-1-silacyclopentanes has been synthesized by four-step reactions starting from 1-chloroalkyltrichlorosilane and tested for fungicidal activities in vitro for ten fungi and in vivo for four fungi occurring in rice, cucumber, tomato etc. Biological activities of the title compounds are strongly dependent upon the p-substituent on the phenyl group in the following order: F > Cl > Ph > OEt > H. Especially, 1-p-fluorophenyl-1-[1-(1H-1,2,4-triazol-1-yl)alkyl]-1-silacyclopentanes (alkyl = methyl or ethyl) showed significant fungicidal activity with a broad spectrum comparable to flusilazole in in-vivo assay.

Selective dechlorination of the chloromethyl-containing silanes (Cl3-nCHn)SiCl3-mMem (n = 0−2 (1−3), m = 0−3 (a−d)) with trichlorosilane was studied in the presence of group 10 transition-metal com...

The Friedel—Crafts alkylation of alkylbenzenes such as toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, o-, m-, p-xylene, and mesitylene with dichloromethylvinylsilane in the presence of aluminum chloride catalyst has been studied under mild conditions. Alkylation with dichloromethylvinylsilane at room temperature gave peralkylated products in yields ranging from 25 to 63%, depending upon the number of substituents on the benzene ring. Less alkylated compounds were also obtained as minor products along with alkyl-reoriented products or transalkylated products. The alkylations of substituted benzenes such as chlorobenzene and anisole did not give the peralkylated products under the same conditions. The molecular structure of tris(dichloromethylsilylethyl)mesitylene has been determined by X-ray diffraction studies. The two chlorosilyl group containing substituents are arranged above the benzene plane and the other one below. Peralkylated compounds were methylated or reduced to the corresponding derivatives by reacting with methyl Grignard reagent and LiAlH4.

Allyltrimethylsilane reacts with simple conjugated dienes in the presence of aluminum chloride catalyst to give stereoselective [3 + 2] cycloadducts of trans-vinylcyclopentanes in 29−72% yields at ...

Friedel−Crafts alkylation of vinyldichloromethylsilane to benzene in the presence of aluminum chloride catalyst at room temperature gave hexakis((dichloromethylsilyl)ethyl)benzene (1) in 56% yield, along with small amounts of less alkylated products. 1 was easily converted to the corresponding compounds, C6(CH2CH2SiMeR2)6; (5 (R = OCH3), 6 (R = H), 7 (R = CH3), 8 (R = vinyl), 9 (R = allyl), 10 (R = ethynyl), and 11 (R = benzyl)) by reaction with the appropriate nucleophilic reagents. The molecular structures of hexakis((methylsilylethyl)benzene (6) and the solvent adducts of hexakis((trimethylsilyl)ethyl)benzene (7·2CH2Cl2) and hexakis((dibenzylmethylsilyl)ethyl)benzene (11·2CHCl3) have been determined by X-ray diffraction studies. Each dichloromethane and chloroform molecule formed C−H···aryl hydrogen bonds, one above and one below, to the ring centroid. The distances between the carbon and the ring centroid were 3.469 and 3.466 A for CH2Cl2 and CHCl3, respectively.

Direct reaction of elemental silicon with a mixture of chloroform and hydrogen chloride has been studied in the presence of a copper catalyst using a stirred reactor equipped with a spiral band agitator at various temperatures from 280 to 340 °C. Tris(chlorosilyl)methanes 1a−e with Si−H bonds were obtained as the major products along with byproducts of bis(chlorosilyl)methanes, derived from the reaction of silicon with methylene chloride formed by the decomposition of chloroform, and trichlorosilane and tetrachlorosilane produced from the reaction of elemental silicon with hydrogen chloride. The decomposition of chloroform was suppressed and the production of polymeric carbosilanes reduced by adding hydrogen chloride to chloroform. The deactivation problem of elemental silicon due to the decomposition of chloroform and polycarbosilanes was eliminated. Cadmium was a good promoter for the reaction, while zinc was found to be an inhibitor for this particular reaction.

Direct synthesis of bis(chlorosily)methanes has been reinvestigated by reacting elemental silicon simultaneously with methylene chloride and hydrogen chloride in the presence of copper catalyst using a stirred reactor equipped with a spiral band agitator at a carefully controlled temperature between 260 and 340°C. Bis(dichlorosily)methane and (dichlorosily)(trichlorosily)methane were obtained as the major products and bis(trichlorosily)methane as a minor product along with trichlorosilabe and tetrachlorosilane derived from the reaction between elemental silicon and hydrogen chloride. The decomposition of methylene chloride was suppressed and the production of polymeric carbosilanes reduced by adding hydrogen chloride to the methylene chloride reactant. The optimum mixing ratio of methylene chloride and hydrogen chloride for the direct synthesis of bis(silyl)methanes was 1:4. The deactivation problem of elemental silicon owing to decomposition of methylene chloride and polycarbosilanes was eliminated. Cadmium was a good promoter for the reaction, while zinc was found to be an inhibitor for this particular reaction.

Allyltrimethylsilane reacts with phenylalkynes in the presence of aluminium chloride catalyst under mild conditions to afford silylphenyldienes in moderate yield. In this allylsilylation reaction, the silyl group adds regioselectively to the terminal carbon and the allyl group to the inner carbon of the triple bond. The allylsilylation of phenylacetylene gives the allylsilylated product having the silyl and allyl groups in the cis -position, while diphenylacetylene gives the trans product. The allylic inversion was also observed in the allylsilylation with the stereohomogeneous ( Z )-crotyltrimethylsilane. These results are consistent with the initial formation of trimethylsilyl cation intermediate and a stepwise process of allylsilylation.

The hydrosilylation of olefins with allyldicholorosilane in the presence of chloroplatinic acid diluted with isopropanol gave allylalkyldichlorosilanes, retaining the allyl group. When the olefin was used in fivefold excess or more relative to allyldichlorosilane, allylalkyldichlorosilanes were obtained in good yields (63–89%), and the formation of double hydrosilylation products was reduced to less than 6%. The isomerization of allylsilane to 1-propenylsilane was suppressed by lowering reaction temperatures below 100°C. This hydrosilylation of olefins with allyldichlorosilane is a good synthetic route to an allyl group containing organodichlorosilanes.

In situ tetrakis(triphenylphosphine)palladium appeared to be a very efficient catalyst for dehydrogenative double silylation of bis- and tris(dichlorosilyl)methanes with acetylenes to produce 1,1,3...

Heating trichlorosilane with conjugated dienes or an acetylene solution at 150 or 180 °C in the presence of a catalytic quantity of tetrabutylphosphonium chloride resulted in elimination of HCl and dichlorosilylene transfer to the unsaturated substrates to afford silacyclopentenes or 1,4-disilacyclohexa-2,5-dienes, respectively, in good to excellent yields. The trapping reaction with hex-3-yne gave 1,1,4,4-tetrachloro-2,3,5,6-tetraethyl-1,4-disilacyclohexa-2,5-diene in 79% yield, and its structure was determined by X-ray crystallography.

A library of emission spectra of 90 bis-cyclometallated iridium complexes has been obtained using a simple combinatorial approach performed at room temperature. Trends in emission maxima are rationalized using Hammett parameters and invoking inter ligand energy transfer (ILET) processes. The screening approach allowed us to observe trends in the broadness of emission spectra opening the way for a rational approach to the engineering of the emission colour purity at a molecular level. Finally limitations to the screening strategy are discussed using a case study that involves two different monodentate ligands.

A series of trisilaalkanes has been prepared in high yields by the direct reaction of -chloromethylsilanes with metallic silicon in the presence of copper catalyst using the stirred reactor equipped with a spiral band agitator at the carefully controlled temperature between and Disilaalkane compounds were obtained as the minor products. Cadmium was found to be a good promotor for the reactions, while zinc was an inhibitor.

The photochemical reactions of 2-R-2-phenyl[5,6: 7,8]dibenzo-2-silabicyclo[2.2.2]octanes (R = Ph, 1, R = Me, 5) in cyclohexane have been studied in the presence or absence of trapping agents such as methanol and methoxytrimethylsilane. The photolysis of 1 in the presence of methanol gave 9-(1,1-diphenylmethoxysilyl-3,3-dimethylbutyl)-9,10-dihydroanthracene as the major product and the methanol adduct of 1,1-diphenyl-2-neopentylsilene as the minor product. When trimethylmethyoxysilane was used as the trap, the silene adduct was only isolated in small quantity and no 9,10-disubstituted anthracene product was obtained. The photolysis of pure Z-5 or E-5 in the absence of trapping agent gave Z - E photoisomerization products and polymeric products. During the photolysis a constant ratio of Z-5 and E-5 was never observed because the formation of high molecular weight products was faster than isomerization. The major product of photolysis of pure E-5 or Z-5 in the presence of methanol or deuterated methanol was SS(RR), 6, and RS(SR), 6′, respectively, at early stages of the reaction but the other diastereomer was produced also as the photolysis proceeded. Photoisomerization of the diastereomers 6 and 6′ also occurred. The 1,6-biradical intermediates formed from Z- and E-5 retain their asymmetry at the silicon atom prior to the abstraction of methoxy group from methanol, but not at carbon.