Equivalents Of N-butyllithium Research Articles

Formation and structure of the first metal complexes comprising amidino-guanidinate ligands.

The first metal complexes comprising amidino-guanidinate ligands have been prepared and structurally characterized, namely bis-[μ-N,N',N'',N'''-tetraisopropyl-1-(1-butyl-amidinato)guanidinato-κ3N1,N2:N2]bis-[(tetra-hydro-furan)lithium], [Li2(C18H37N4)2(C4H8O)2], (2), and [bis-(tetra-hydro-furan)-lithium]-di-μ-chlorido-{(N,N'-di-cyclo-hexyl-1-butyl-amidinato-κ2N1,N2)[N,N',N'',N'''-tetra-cyclo-hexyl-1-(1-butyl-amidinato)guanidinato-κ2N1,N2]holmate(III)}, [HoLiCl2(C4H8O)2(C17H31N2)(C30H53N4)], (3). The novel lithium amidino-guanidinate precursors Li[ n BuC(=NR)(NR)C(NR)2] [1: R = Cy (cyclo-hex-yl), 2: R = i Pr) were obtained by treatment of N,N'-diorganocarbodi-imides, R-N=C=N-R (R = i Pr, Cy), with 0.5 equivalents of n-butyl-lithium under well-defined reaction conditions. An X-ray diffraction study of 2 revealed a ladder-type dimeric structure in the solid state. Reaction of anhydrous holmium(III) chloride with in situ-prepared 2 afforded the unexpected holmium 'ate' complex [ n BuC(=NCy)(NCy)C(NCy)2]Ho[ n BuC(NCy)2](μ-Cl)2Li(THF)2 (3) in 71% yield. An X-ray crystal structure determination of 3 showed that this complex contains both an amidinate ligand and the new amidino-guanidinate ligand.

A facile method for the preparation of bishomopropargylic alcohols from acyl chlorides

Controlled dilithiation of propargyl bromide with two equivalents of n-butyllithium, in the presence of TMEDA, produces the operational equivalent of the dianion 1,3-dilithiopropyne. The latter reacts efficiently with acid chlorides to produce bishomopropargylic alcohols in a single step route and with high regioselectivity and moderate yields.

Magnesium and zinc complexes containing pendant pyrazolyl–phenolate ligands as catalysts for ring opening polymerisation of cyclic esters

Reactions of HOPhtBu(CH2)Pz {4,6-di-tert-butyl-2-(pyrazol-1-yl-methyl)phenol} or HOPhtBu(CH2)PzMe {4,6-di-tert-butyl-2-(3,5-dimethylpyrazol-1-yl-methyl)phenol} with 1.1 equivalent of MgnBu2 in toluene gave the binuclear compounds (nBuMgOPhtBu(CH2)Pz)2 (1) or (nBuMgOPhtBu(CH2)PzMe)2 (2). Treatment of HOPhtBu(CH2)Pz or HOPhtBu(CH2)PzMe with 1.1 equivalent of ZnEt2 in n-hexane yielded binuclear compounds (EtZnOPhtBu(CH2)Pz)2 (3) and (EtZnOPhtBu(CH2)PzMe)2 (4). Colourless crystals of (ClZnOPhtBu(CH2)Pz)2 (5) were obtained via the recrystallisation of 3 from a concentrated dichloromethane solution at room temperature. Alternative route for the synthesis of 5 can be achieved via the reaction of HOPhtBu(CH2)Pz with 1.1 equivalent of n-butyllithium in diethylether followed by the treatment of 1.1 equivalent of ZnCl2 in tetrahydrofuran gave compound 5 as binuclear chloride complex. The compounds 2 and 5 were crystallographically characterised. The catalytic activities of 1–5 towards the ring opening polymerisation reactions of cyclic esters in the presence of benzyl alcohol were under investigation.

Variation in the Site of Lithiation of 2-(2-Methylphenyl)ethanamine Derivatives

Unexpectedly, lithiation of N'-(2-(2-methylphenyl)ethyl)-N,N-dimethylurea with 3 equiv of n-butyllithium in anhydrous THF at 0 °C takes place on the nitrogen and on the CH(2) next to the 2-methylphenyl ring (α-lithiation). The lithium reagent thus obtained reacts with various electrophiles to give the corresponding substituted derivatives in excellent yields. Similarly, lithiation of N-(2-(2-methylphenyl)ethyl)pivalamide under similar reaction conditions followed by reaction with benzophenone as a representative electrophile gave the corresponding α-substituted product in high yield. Surprisingly, no products resulting from lateral lithiation were observed under the conditions tried, which sharply contrasts with the reported results for lateral lithiation of tert-butyl (2-(2-methylphenyl)ethyl)carbamate.

Dinitrogen Complexation and Extent of N≡N Activation within the Group 6 “End-On-Bridged” Dinuclear Complexes, {(η5-C5Me5)M[N(i-Pr)C(Me)N(i-Pr)]}2(μ-η1:η1-N2) (M = Mo and W)

Chemical reduction of Cp*M[N(i-Pr)C(Me)N(i-Pr)]Cl(3) (Cp* = eta(5)-C(5)Me(5)) (1, M = Mo) and (2, M = W) using 0.5% NaHg in THF provided excellent yields of the diamagnetic dinuclear end-on-bridged dinitrogen complexes {Cp*M[N(i-Pr)C(Me)N(i-Pr)]}(2)(mu-eta(1):eta(1)-N(2)) (6, M = Mo) and (8, M = W), respectively. Chemical reduction of Cp*Mo[N(i-Pr)C(NMe(2))N(i-Pr)]Cl(2) (4) with 3 equiv of KC(8) in THF similarly yielded diamagnetic {Cp*Mo[N(i-Pr)C(NMe(2))N(i-Pr)]}(2)(mu-eta(1):eta(1)-N(2)) (7). Single-crystal X-ray analyses of 7 and 8 confirmed the dinuclear end-on-bridged mu-eta(1):eta(1)-N(2) coordination mode and the solid-state molecular structures of these compounds provided d(NN) values of 1.267(2) and 1.277(8) A for 7 and 8, respectively. Based on a comparison of (15)N NMR spectra for (15)N(2) (99%)-labeled 6 and (15)N(2) (99%)-labeled 8, as well as similarities in chemical reactivity, a dinuclear mu-eta(1):eta(1)-N(2) structure for 6 is further proposed. For comparison with a first-row metal derivative, chemical reduction of Cp*Ti[N(i-Pr)C(Me)N(i-Pr)]Cl(2) (9) with KC(8) in THF was conducted to provide {Cp*Ti[N(i-Pr)C(Me)N(i-Pr)]}(2)(mu-eta(1):eta(1)-N(2)) (10) for which a d(NN) value of 1.270(2) A was obtained through X-ray crystallography. Compounds 6-8 were all found to be thermally robust in toluene solution up to temperatures of at least 100 degrees C, and 6 and 8 were determined to be inert toward the addition of H(2) or H(3)SiPh under a variety of conditions. Single-crystal X-ray analysis of meso-{Cp*Mo(H)[N(i-Pr)C(Me)N(i-Pr)]}(2)(mu-eta(1):eta(1)-N(2)) (meso-11), which was serendipitously isolated as a product of attempted alkylation of Cp*Mo[N(i-Pr)C(Me)N(i-Pr)]Cl(2) (3) with 2 equiv of n-butyllithium, revealed a smaller d(NN) value of 1.189(4) A that is consistent with two Mo(IV,d(2)) centers connected by a bridging diazenido, [mu-N(2)](2-), moiety. Moreover, meso-11 was found to undergo clean dehydrogenation in solution at 50 degrees C to provide 6 via a first-order process. Chemical oxidation of 8 with an excess of PbCl(2) in toluene solution at 25 degrees C provided a 1:1 mixture of rac- and meso-{Cp*W(Cl)[N(i-Pr)C(Me)N(i-Pr)]}(2)(mu-eta(1):eta(1)-N(2)) (12); both isomers of which provided solid-state structures through X-ray analyses that are consistent with an electronic configuration comprised of two W(IV,d(2)) centers linked through a bridging [N(2)](2-) group [cf. for rac-12, d(NN) = 1.206(9) A, and for meso-12, d(NN) = 1.192(3) A]. Finally, treatment of 6 and 8 with either 4 equiv of CNAr (Ar = 3,5-Me(2)C(6)H(3)) or an excess of CO in toluene provided excellent yields of Cp*M[N(i-Pr)C(Me)N(i-Pr)](CNAr)(2) (13, M = Mo and 14, M = W) and Cp*M[N(i-Pr)C(Me)N(i-Pr)](CO)(2) (15, M = Mo and 16, M = W), respectively. Single-crystal X-ray analyses of 13-16, along with observation of reduced IR vibrational nu(CN) or nu(CO) bond-stretching frequencies, provide strong support for the electron-rich character of the Cp*M[N(i-Pr)C(Me)N(i-Pr)] fragment that can engage in a high degree of back-donation with moderate to strong pi-acceptors, such as N(2), CNR, and CO. The collective results of this work are analyzed in terms of the possible steric and electronic factors that contribute to preferred mode of mu-N(2) coordination and the extent of N[triple bond]N activation, including complete N-N bond scission, within the now completed experimentally-derived ligand-centered isostructural series of {Cp*M[N(i-Pr)C(Me)N(i-Pr)]}(2)(mu-N(2)) compounds where M = Ti, Zr, Hf, Ta, Mo, and W.

Darstellung, Kristall‐ und Molekülstruktur eines zwölfgliedrigen N,N′‐Di‐Lithium‐cyclosiloxazans [Me2SiOSiMe2N(Li)SiMe2O]2

AbstractThe twelve membered and eighteen membered cyclosiloxazanes [Me2SiOSiMe2N(H)SiMe2O]2 (3) and [Me2SiOSiMe2N(H)SiMe2O]3 (4) have been obtained as colourless liquids from the reaction of 1,5‐Dichlorohexamethyltrisiloxane with ammonia at–50 °C without any solvent. For compound 3 and 4, the yield is 30 % and 43 %, respectively. The treatment of 3 with two equivalents of n‐butyllithium in n‐hexane leads in almost quantitative yield (93 %) to the dilithiumsilylamide [Me2SiOSiMe2N(Li)SiMe2O]2 (5). Compound 5 can be isolated at room temperature and recrystallized from benzene without any decomposition or contraction of the ring size. An X‐ray structure determination on [Me2SiOSiMe2N(Li)SiMe2O]2 (5) reveals a waved crown‐like twelve membered Si6N2O4‐cycle. Each of the two lithium ions is coordinated by two nitrogen and two oxygen atoms leading to a square pyramid, in which the metal occupies the apex. The two square‐pyramidal coordination figures are located above and below the waved crown‐like Si6N2O4‐ring sharing a common edge by the atoms N(1) and N(2). All synthesised compounds have been characterised by spectroscopic methods. Because of the lower solubility of the dilithiumsilylamide 5, only a 1H‐NMR could be applied for further characterisation in solution.

Synthesis of unsymmetrically substituted biaryls via sequential lithiation of dibromobiaryls using integrated microflow systems

A microflow system consisting of micromixers and microtube reactors provides an effective method for the introduction of two electrophiles onto dibromobiaryls. Selective monolithiation of dibromobiaryls, such as 2,2′-dibromobiphenyl, 4,4′-dibromobiphenyl, 2,7-dibromo-9,9-dioctylfluorene, 2,2′-dibromo-1,1′-binaphthyl, and 2,2′-dibromobibenzyl with 1 equiv of n-butyllithium followed by the reaction with electrophiles was achieved using a microflow system by virtue of fast micromixing and precise temperature control. Sequential introduction of two different electrophiles was achieved using an integrated microflow system composed of four micromixers and four microtube reactors to obtain unsymmetrically substituted biaryl compounds.

Reductions of Aliphatic and Aromatic Nitriles to Primary Amines with Diisopropylaminoborane

Diisopropylaminoborane [BH(2)N(iPr)(2)] in the presence of a catalytic amount of lithium borohydride (LiBH(4)) reduces a large variety of aliphatic and aromatic nitriles in excellent yields. BH(2)N(iPr)(2) can be prepared by two methods: first by reacting diisopropylamineborane [(iPr)(2)N:BH(3)] with 1.1 equiv of n-butyllithium (n-BuLi) followed by methyl iodide (MeI), or reacting iPrN:BH(3) with 1 equiv of n-BuLi followed by trimethylsilyl chloride (TMSCl). BH(2)N(iPr)(2) prepared with MeI was found to reduce benzonitriles to the corresponding benzylamines at ambient temperatures, whereas diisopropylaminoborane prepared with TMSCl does not reduce nitriles unless a catalytic amount of a lithium ion source, such as LiBH(4) or lithium tetraphenylborate (LiBPh(4)), is added to the reaction. The reductions of benzonitriles with one or more electron-withdrawing groups on the aromatic ring generally occur much faster with higher yields. For example, 2,4-dichlorobenzonitrile was successfully reduced to 2,4-dichlorobenzylamine in 99% yield after 5 h at 25 degrees C. On the other hand, benzonitriles containing electron-donating groups on the aromatic ring require refluxing in tetrahydrofuran (THF) for complete reduction. For instance, 4-methoxybenzonitrile was successfully reduced to 4-methoxybenzylamine in 80% yield. Aliphatic nitriles can also be reduced by the BH(2)N(iPr)(2)/cat. LiBH(4) reducing system. Benzyl cyanide was reduced to phenethylamine in 83% yield. BH(2)N(iPr)(2) can also reduce nitriles in the presence of unconjugated alkenes and alkynes such as the reduction of 2-hexynenitrile to hex-5-yn-1-amine in 80% yield. Unfortunately, selective reduction of a nitrile in the presence of an aldehyde is not possible as aldehydes are reduced along with the nitrile. However, selective reduction of the nitrile group at 25 degrees C in the presence of an ester is possible as long as the nitrile group is activated by an electron-withdrawing substituent. It should be pointed out that lithium aminoborohydrides (LABs) do not reduce nitriles under ambient conditions and behave as bases with aliphatic nitriles as well as nitriles containing acidic alpha-protons. Consequently, both LABs and BH(2)N(iPr)(2) are complementary to each other and offer methods for the selective reductions of multifunctional compounds.

Selective Monolithiation of Dibromobiaryls Using Microflow Systems

Selective monolithiation of dibromobiaryls, such as 2,2'-dibromobiphenyl, 4,4'-dibromobiphenyl, 2,7-dibromo-9,9-dioctylfluorene, 2,2'-dibromo-1,1'-binaphthyl, and 5,5'-dibromo-2,2'-bithiophene, with 1 equiv of n-butyllithium followed by the reaction with electrophiles was achieved using a microflow system by virtue of fast micromixing and precise temperature control. Sequential introduction of two different electrophiles based on this method was also achieved using a microflow system composed of four micromixers and four microtube reactors.

N-versus O-silylation in cis-[( tBuHN)O [dbnd]P(μ-N tBu) 2P [dbnd]O(NH tBu)] and [Me 2Si(μ-N tBu) 2P [dbnd]O(NHPh)]. Solid-state structures of their silylation products, of co-crystalline cis-[( tBuHN)O [dbnd]P(μ-N tBu) 2P [dbnd]O(NH tBu)], and of {[Me 2Si(μ-N tBu) 2P [dbnd]O(N(SiMe 3)Ph)]VCl 3}

The solid-state structure of cis-[( t BuHN)O P(μ-N t Bu) 2P O(NH t Bu)] ( A), isolated as a 2-phenyl-2-propanol/2-phenyl-2-propanehydroperoxide co-crystal ( 1), is reported. Treatment of pure A with two equivalents of n-butyllithium, followed by addition of Me 3SiCl, afforded the bis- O, O′-silylated cis-[(Me 3SiO) t BuN P(μ-N t Bu) 2P N t Bu(OSiMe 3)] ( 2), whose solid-state structure was determined. When the cyclic N, N, N-phosphoramidate [Me 2Si(μ-N t Bu) 2P O(NHPh)] ( B) was subjected to the same treatment as A, however, the N-silylated [(Me 2Si(μ-N t Bu) 2P O(N(SiMe 3)Ph)] ( 3), was obtained. Its solid-state structure was determined. The reaction of 3 with VCl 3(THF) 3 did not produce the intended N, O-chelated V(II) complex, but furnished instead the adduct {[Me 2Si(μ-N t Bu) 2P O(N(SiMe 3)Ph)] VCl 3(THF)}, in which 3 binds the trigonal-bipyramidally coordinated vanadium center through its oxygen atom only.

Crystal structure of tetra-μ3-bromo-tetrakis(tert-butyl-(4-methyl-pyridin-2-yl)-amine)-tetracopper(I), Cu4Br4(C10H16N2)4

C40H64Br4Cu4N8, tetragonal, P42/n (no. 86), a = 15.325(1) A, c = 10.5050(6) A, V = 2467.2 A, Z = 2, Rgt(F) = 0.056, wRref(F) = 0.162, T = 191 K. Source of material A solution of two equivalents of tert-butyl-(4-methyl-pyridin-2yl)-amine in THF was treated at –50 °C with two equivalents of n-butyllithium followed by a reaction with one equivalent of CuBr2 suspended inTHF.After removal of the solvent the residue was extracted twice with hexane and filtered. Colorless crystals suitable for X-ray analysis were obtained after slow evaporation of the solvent. Experimental details TheH atom bonded to theN atom was located and refined due to its importance in the hydrogen bonding pattern. Discussion During the last decades, tetranuclear copper(I) clusters have been widely studied. They are known for all possible halides, but for copper(I) bromides the structural data are rare [1-3]. The title compound is a new member of the tetra[%3-bromo-copper(I)] family. The four Cu atoms form an almost regular tetrahedron (Cu—Cu bond lengths of 2.811A and 2.883A).The%3-coordinated bromo ligands cap the faces of the tetrahedron (d(Br1—Cu1) = 2.422A, d(Br1—Cu1A) = 2.438 A, d(Br1—Cu1B) = 2.794 A). Furthermore eachCu atom coordinates a tert-butyl-(4-methyl-pyridin-2yl)-amine with a Cu—Npyridine distance of 2.021 A. The orientation of the amines indicates the formation of intramolecular hydrogen bonds of the amino H atoms to the adjacent Br atoms (d(N2H···Br) = 2.927 A). Z. Kristallogr. NCS 222 (2007) 261-262 / DOI 10.1524/ncrs.2007.0110 261 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless prism, size 0.34 × 0.36 × 0.61 mm Wavelength: Mo K0 radiation (0.71069 A) %: 49.75 cm−1 Diffractometer, scan mode: Stoe IPDS II, ) 2'max: 51.58° N(hkl)measured, N(hkl)unique: 9086, 2362 Criterion for Iobs, N(hkl)gt: Iobs > 2 ((Iobs), 1808 N(param)refined: 131 Programs: SIR97 [4], SHELXL-97 [5] Table 1. Data collection and handling. H(1) 8g 0.2424 0.1257 −0.1071 0.049 H(4) 8g −0.0559 0.1011 −0.1328 0.051 H(9A) 8g −0.1467 0.0703 0.1506 0.092 H(9B) 8g −0.1535 0.0917 0.0018 0.092 H(9C) 8g −0.2151 0.1415 0.1011 0.092 H(2) 8g 0.1798 0.0936 −0.3026 0.049 H(10A) 8g −0.0470 0.2700 0.2477 0.097 H(10B) 8g −0.0809 0.1779 0.2996 0.097 H(10C) 8g −0.1494 0.2501 0.2535 0.097 H(8A) 8g −0.0555 0.3047 0.0220 0.093 H(8B) 8g −0.1583 0.2868 0.0219 0.093 H(8C) 8g −0.0967 0.2373 −0.0776 0.093 H(6A) 8g 0.0561 0.0568 −0.4248 0.105 H(6B) 8g −0.0303 0.1092 −0.3862 0.105 H(6C) 8g −0.0194 0.0091 −0.3459 0.105 H(2N) 8g 0.032(4) 0.149(4) 0.149(5) 0.02(2) Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso

Dioxomolybdenum(vi) and dioxotungsten(vi) complexes supported by an amido ligand

Stepwise addition of one equivalent of n-butyllithium and trimethylsilyl chloride to 2-tert-butylmercaptoaniline affords the new ligand 1-(Me3SiNH)-2-(t-BuS)C6H4 (LH), that reacts with one equivalent of butyllithium to its lithium salt LLi. Dioxodichloromolybdenum [MoO2Cl2] and dioxodichlorotungsten dimethoxyethane [WO2Cl2(dme)] react in tetrahydrofuran solution at low temperature with two equivalents LLi to monomeric dioxomolybdenum(VI) [MoO2L2] (1) and dioxotungsten(VI) complex [WO2L2] (2) employing two bidentate amido thioether ligands. The crystallographic determination of the molecular structures of 1 and 2 show evidence for M...S contacts. The reaction of [MoO2Cl2] with LLi in tetrahydrofuran solution at room temperature leads next to 1 to two compounds where silyl group migration from nitrogen to oxygen atoms occurs forming [Mo(=NL')2(OSiMe)2] (3) and [Mo(=NL')2(OSiMe3)L] (4, L' = N-2-t-BuSC6H4) as determined by NMR spectroscopy. Compound 4 was isolated in low yield and its molecular structure determined by X-ray crystallography. Higher yields of a bisimido complex can be obtained by the direct reaction of one equivalent of LLi with [Mo(NAr)2Cl2(dme)] (Ar = 2,6-Me2C6H4) forming [Mo(NAr)2LCl] (5).

γ‐Butyltelluro‐2‐butanol: A Route to Reactive 1,4‐Dianion Intermediates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Another example of carborane based trianionic ligand: Syntheses and catalytic activities of cyclohexylamino tailed ortho-carboranyl zirconium and titanium dicarbollides

In situ reaction of Li[ closo-1-Ph-1,2-C 2B 10H 10] with 7-azabicyclo [4.1.0] heptane results in the formation of the disubstituted carborane, closo-1-Ph-2-(2′-aminocyclohexyl)-1,2-C 2B 10H 10 ( 1), in 63% yield. Decapitation of (1) with potassium hydroxide in refluxing ethanol produces the cage-opened nido-carborane, K[ nido-7-Ph-8-(2′-aminocyclohexyl)-7,8-C 2B 9H 10] − ( 2), in 80% yield. Deprotonation of the above monoanion with two equivalents of n-butyllithium followed by reaction with anhydrous MCl 4 · 2THF (M = Zr, Ti) provides d 0-half-sandwich metallocarboranes, closo-1-M(Cl)-2-Ph-3-(2′- σ-(H) N-cyclohexyl)-2,3- η 5-C 2B 9H 9 ( 3 M = Zr; 4 M = Ti) in 53% and 42% yields, respectively. The reaction of Li[ closo-1,2-C 2B 10H 11] with 7-azabicyclo [4.1.0] heptane in THF affords closo-1-(2′-aminocyclohexyl)-1,2-C 2B 10H 10 ( 5) in 59% yield. Immobilization of the carboranyl amino ligand ( 1) to an organic support, Merrifield’s peptide resin (1%), has been achieved by the reaction of the sodium salt of (5) with polystyryl chloride in THF to produce closo-1-(2′-aminocyclohexyl)-2-polystyryl-1,2-C 2B 10H 10 ( 6) in 87% yield. Further reaction of the dianion derived from ( 6) with anhydrous ZrCl 4 · 2THF led to the formation of the organic polystyryl supported d 0-half-sandwich metallocarborane, closo-1-Zr(Cl)-2-(2′- σ-(H) N-cyclohexyl)-3-polystyryl-2,3-η 5-C 2B 9H 9 ( 7), in 38% yield. These new compounds have been characterized by elemental analyses, NMR, and IR spectra. Polymerizations of both ethylene and vinyl chloride with (3) and ( 7) have been performed in toluene using MMAO-7 (13% ISOPAR-E) as the co-catalyst. Molecular weights up to 32.8 × 10 3 ( M w/ M n = 1.8) and 9.5 × 10 3 ( M w/ M n = 2.1) were obtained for PE and PVC, respectively.

γ-Butyltelluro-2-butanol: a route to reactive 1,4-dianion intermediates

γ-Butyltelluro-2-butanol was reacted with 2 equiv of n-butyllithium. Both tellurium/lithium exchange and the proton abstraction reactions took place in a single step and the lithium dianion intermediate efficiently reacted with aldehydes and ketones, producing the corresponding diols.

Syntheses and catalytic activities of Group 4 metal complexes derived from C (cage)-appended cyclohexyloxocarborane trianion

The reaction of Li[ closo-1-Me-1,2-C 2B 10H 10] with cyclohexene oxide produced closo-1-Me-2-(2′-hydroxycyclohexyl)-1,2-C 2B 10H 10 ( 1) in 86% yield. Decapitation of ( 1) with potassium hydroxide in refluxing ethanol gave the corresponding cage-opened potassium salt of the carborane anion, [ nido-1-Me-2-(2′-hydroxycyclohexyl)-1,2-C 2B 9H 10] − ( 2) in 82% yield. Deprotonation of ( 2) with two equivalents of n-butyllithium in THF at −78 °C, followed by its further reaction with anhydrous MCl 4 · 2THF (M = Ti, Zr) produced the corresponding d 0-half-sandwich metallacarboranes, closo-1-M(Cl)-2-Me-3-(2′-σ- O-cyclohexyl)-η 5-2,3-C 2B 9H 9 ( 3 M = Zr; 4 M = Ti), in 59% and 51% yields, respectively. Reaction of Li[ closo-1,2-C 2B 10H 11] with Merrifield’s peptide resin (1%) in refluxing THF gave the ortho-carborane-functionalized polymer ( 5) in 88% yield. The corresponding closo-1-polystyryl-2-(2′-hydroxycyclohexyl)-1,2-C 2B 10H 10 ( 6) was produced in 94% yield by refluxing a mixture of the lithium salt of ( 5) and cyclohexene oxide in THF for 2 days. Compound ( 6) was decapitated, deprotonated and then reacted with ZrCl 4 · 2THF to produce a polymer-supported d 0-half-sandwich metallacarborane closo-1-Zr(Cl)-2-polystyryl-3-(2′-σ- O-cyclohexyl)-η 5-2,3-C 2B 9H 9 ( 7) in 41% yield. Compounds ( 3) and ( 7), in the presence of MMAO-7 (13% ISOPAR-E), were found to catalyze the polymerization of ethylene and vinyl chloride in toluene to give high molecular weight PE (9.4 × 10 3 ( M w/ M n = 1.8)) and PVC (2.1 × 10 3 ( M w/ M n = 1.6)), respectively.

Preparation and Functionalization of a Range of Main-Group Trifluoropropynyl Organometallic Compounds: The Application of Metalloid-Directed Carbolithiation to the Selective Synthesis of Novel Fluorocarbon Fragments

The reaction of 1,1,1,3,3-pentafluoropropane (CF3CH2CF2H, HFC-245fa) with 3 equiv of n-butyllithium. at -10 degreesC leads to the generation of trifluoropropynyllithium in excellent yields. This reagent reacts readily with a range of group 14 electrophiles R4-nEXn (R = Ph, Et; E = C, Si, Ge, Sn, Ph; X = Cl, Br) to yield the organometalloid trifluoropropynyl compounds R4-nE(Cequivalent toCCF(3))(n). Three of these compounds, Ph(3)ECequivalent toCCF(3) (E = C, Si, Ge), have been crystallographically characterized, representing the first such study of these materials. The silane Ph(3)SiCequivalent toCCF(3) has been derivatized by reaction with LiAlH4 and a range of organolithium reagents (RLi, R = n-Bu, Ph, t-Bu) to afford a new series of beta-CF3-substituted vinylsilanes of the type Ph3SiCH=C(CF3)R, with predominantly E geometry at the double bond. In the cases R = n-Bu, t-Bu, and Ph, these materials have been crystallographically characterized. Additionally, a remarkably facile cyclization pathway for Ph(3)SiCequivalent toCCF(3), initiated by t-BuLi, that yields the respective gem-difluorocyclopropene has been explored and is described in detail, along with its extension to a number of other systems.

A homologous series of crown-ether-complexed alkali metal amides as discrete ion-pair species: synthesis and structures of [M(12-crown-4) 2][PyNPh · PyN(H)Ph] (M=Li, Na and K)

Reaction between one equivalent of n-butyllithium and 2-phenylaminopyridine, in the presence of 12-crown-4 ether (12C4) in toluene, affords the discrete ion-pair complex [{Li(12C4) 2}{N(Py)(Ph) · HN(Py)(Ph)}] ( 1), in which the secondary amine proton is hydrogen-bonded to the secondary amide anion. Compound 1 is the sole isolable product of this reaction, irrespective of the amount of lithium alkyl employed, metallation never exceeding 50%. Metathesis of 1 with sodium- or potassium- tert-butoxide affords the homologous complexes [{Na(12C4) 2}{N(Py)(Ph) · HN(Py)(Ph)}] ( 2) and [{K(12C4) 2}{N(Py)(Ph) · HN(Py)(Ph)}] ( 3), respectively. Compounds 1, 2 and 3 have all been characterised by X-ray crystallography, NMR spectroscopy and elemental analysis.

CH-Aktivierungsreaktionen an unverbrückten und verbrückten Zirconocenkomplexen zur Darstellung von Metallacyclen und deren Verwendung in der katalytischen Ethylenpolymerisation

The reaction of phenylalkyl substituted zirconocenedichloride complexes with two equivalents of n-butyllithium gives metallacyclic zirconocene complexes. In this reaction aromatic CH bonds can be activated in unbridged and bridged metallocenedichloride complexes even if the corresponding phenyl rings contain halogen substituents such as fluorine or chlorine. After the activation with methylalumoxane (MAO), all the metallocene complexes prove as attractive catalysts for ethylene polymerization reactions. Because of their Lewis basicity the halogen substituents fluorine or chlorine have a strong influence on the molecular weights of the produced polyethylenes. Metallocene complexes with chloro substituents in the ortho positions of the phenyl rings produce bimodal polyethylenes.

Umsetzungen von ω-alkenylsubstituierten Zirconocendichloridkomplexen mit n-Alkyllithiumverbindungen in Gegenwart von Alkenen bzw. Alkinen

The reaction of ω-alkenyl substituted zirconocene dichloride complexes with two equivalents of n-butyllithium is strongly influenced in the presence of alkenes and alkynes. Metallacyclic zirconocene complexes of novel structures are obtained. The additives alkenes and alkynes compete with the ω-alkenyl substituents and the intermediate 1-butene for the formation of a metallacyclic structure. The reaction of ω-alkenyl substituted zirconocene dichloride complexes with two equivalents of ethyllithium and n-hexyllithium gives analogous reactions and metallacycles as with n-butyllithium.