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1.
139La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C 4H 8O 2) 3/2 [La(ν 3-C 3H 5) 4], [Li(C 4H 8O 2) 2][Cp′ nLa(ν 3-C 3]H 5) 4−n] (Cp′ = Cp(ν 5-C 5H 5); n = 1, 2 and Cp′ = Cp * (ν 5-C 5Me5); N = 1) and Li[R nLa(ν 3-C 3H 4) 4− n] (R = N(SiMe 3) 2; n = 1, 2 and R = CCsIMe 3; n = 4), as well as for neutral compounds for formulae La(ν 3-C 3H 5) 3L n (L = (C 4H 8O 2) 1.5, (HMPT) 2, TMED), Cp′ nLa(ν 3-C 3H 5) 3−n (Cp′= Cp(ν 5-Cp 5H 5), Cp *(ν 5-C 5Me 5); n = 1, 2) and La(ν 3-C 3H 2) 2X(THF) 2 X = Cl, Br, I). Typical ranges of the 139La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum. Zusammenfassung139La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung
]- [La)ν3-C3H5)4, [Li(C4H8)2][Cp′nLa(ν3-C3H5)4−n(Cp′ = Cp(ν5-C5H5); n = 1, 2 und Cp′ = Cp * (ν5-C5Me5); N = 1) und Li[RnLa(ν3-C3H5)4−n (R = B(SiMe3)2; n = 1, 2 und R = CCSiMe3; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν3-C3H5)3Ln (Ln = (C4H8O2)1.5, (HMPT)2, TMED), Cp′n, La(ν3-C3H5)3−n (Cp′ = Cp(ν5-C5H5), Cp * (ν5- Cp5Me5); n = 1, 2) und La(ν3-Cp3H5)2X(THF)2 (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt. 相似文献
2.
Octakis(alkyloxyphenyl)-phthalocyanine derivatives ((C nOph) 8PcH 2 n = 8, 10 12 and 18), their corresponding copper (II) complexes ((C nOph) 8PcCu, n = 10, 12 and 18) and octakis(2-ethylhexyl)-PcH 2 have been synthesized and their mesomorphic properties characterized. (C nOph) 8PcH 2, ( n = 12 and 18) exhibit hexagona disordered columnar mesophases whereas (C nOph) 8PcCu ( n = 12 and 18) yields a rectangular disordered columnar liquid crystal. An alkylphenyl-oxymethyl derivative, (C 12phOCH 2) 8PcH 2, was synthesized to determine the influence of the connecting link between the side chains and the phthalocyanine macrocycle on the mesomorphic properties. 相似文献
3.
A density functional theory investigation on a series of sandwich-type transition metal complexes [(CBO) n] 2M ( n=4–6; M=transition metals) with carbon boronyls (CBO) n as effective aromatic ligands has been presented in this work at B3LYP level. The ground-states of these complexes possess staggered Dnd symmetries, while the corresponding eclipsed Dnh structures exist as transition states with slightly higher energies (within 5.8 kJ/mol). Carbon boronyl complexes [(CBO) n] 2M are confirmed to be much more stable than their boron carbonyl isomers [(BCO) n] 2M, which, on the other hand, take eclipsed ground-states with Dnh symmetries. The carbon boronyl complexes [(BCO) n] 2M proposed in this work parallelize the well-known sandwich-type hydrocarbon complexes [C nH n] 2M in coordination chemistry with boronyl groups –BO isolobal to –H atoms in corresponding ligands. 相似文献
4.
Recent results (post-1990) on the synthesis and structures of bis(trimethylsilyl)methyls M(CHR 2) m (R = SiMe 3) of metals and metalloids M are described, including those of the crystalline lipophilic [Na(μ-CHR 2)] ∞, [Rb(μ-CHR 2)(PMDETA)] 2, K 4(CHR 2) 4(PMDETA) 2, [Mg(CHR 2)(μ-CHR 2)] ∞, P(CHR 2) 2 (gaseous) and P 2(CHR 2) 4, [Yb(CHR 2) 2(OEt 2) 2] and [{Yb(CR 3)(μ-OEt)(OEt 2)} 2]; earlier information on other M(CHR 2) m complexes and some of their adducts is tabulated. Treatment of M(CHR 2) (M = Li or K) with four different nitriles gave the X-ray-characterized azaallyls or β-diketinimates
,
and
(LL′ = N(R)C( tBu)CHR, L′L′ = N(R)C(Ph)C(H)C(Ph)NR, LL″ = N(R)C(Ph)NC(H)C(Ph)CHR, R = SiMe 3 and Ar = C 6H 3Me 2-2,5). The two lithium reagents were convenient sources of other metal azaallyls or β-diketinimates, including those of K, Co(II), Zr(IV), Sn(IV), Yb(II), Hf(IV) and U(VI)/U(III). Complexes having one or more of the bulky ligands [LL′] −, [L′L′] −, [LL] −, [LL″] −, [L″L] −, [LL] − and [{N(R)C( tBu)CH} 2C 6H 4-2] 2− are described and characterized (LL = N(H)C(Ph)C(H)C(Ph)NH, L″L = N(R)C( tBu)C(H)C(Ph)NR, LL = N(R)C( tBu)CHPh). Among the features of interest are (i) the contrasting tetrahedral or square-planar geometry for
and
, respectively, and (ii) olefin-polymerization catalytic activity of some of the zirconium(IV) chlorides. 相似文献
5.
The synthesis and reactivity of {(η 5-C 5H 4SiMe 3) 2Ti(CCSiMe 3) 2} MCl 2 (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2 (1) with equimolar amounts of MCl 2 (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2 (1) and [Fe(dipy) 2]Cl 2 (5a) or [Fe(phen) 2]Cl 2 (5b). 1/ n[Cu IHal] n (6) or 1/ n[Ag IHal] n (7) (Hal = Cl, Br) react with {(η 5 -C 5H 4SiMe 3) 2Ti(CCSiMe 3) 2}FeCl 2 (3a), by replacement of the FeCl 2 building block in 3a, to yield the compounds {(η 5-C 5H 4SiMe 3) 2Ti(C CSiMe 3) 2}Cu IHal (8) or {(η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2}Ag IHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me 3SiCC-units is η 2-coordinated to monomeric Cu I Hal or Ag IHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η 5-C 5H 4SiMe 3) 2 Ti(CSiMe 3) 2 (1) with 1/ n[Cu IHal] n (6) or 1/ n [Ag IHal] n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, 1H-NMR, MS). The magnetic moments of compounds 3 were measured. 相似文献
6.
Reactions of Co 3(μ 3-CBr)(μ-dppm)(CO) 7 with {Au[P(tol) 3]} 2{μ-(CC) n} ( n=2–4) have given {Co 3(μ-dppm)(CO) 7}{μ 3:μ 3-C(CC) nC} [ n=2 (1), 3 (2), 4 (3)] containing carbon chains capped by the cobalt clusters. Tetracyanoethene reacts with 2 to give {Co 3(μ-dppm)(CO) 7} 2{μ 3:μ 3-C(CC) 2C[=C(CN) 2]C[=C(CN) 2]C} (4). X-ray structural characterisation of 1, 3 and 4 are reported, that for 3 being the first of a cluster-capped C 10 chain. 相似文献
7.
Using velocity map ion imaging technique, the photodissociation of n-C 4H 9Br in the wavelength range 231–267 nm was studied. The results and our ab initio calculations indicated that the absorption of n-C 4H 9Br in the investigated region originated from the excitations to the lowest three repulsive states, as assigned as 1A″, 2A′ and 3A′ in C s symmetry. Dissociations occurred on the PES surfaces of the three states, terminating in C 4H 9+Br ( 2P 3/2) or C 4H 9 + Br * ( 2P 1/2) as two channels, and being impacted by an avoided crossing between the PES surfaces of the 2A′ and 3A′ states. The transition dipole to the 1A″ state was perpendicular to the symmetry plane, so perpendicular to the C–Br bond. The transitions to the 3A′ state was polarized parallel to the symmetry plane, and also parallel to the C–Br bond. While the transition dipole to the 2A′ state was in the symmetry plane, but formed an angle of about 53.1° with the C–Br bond. We have also determined the avoided crossing probabilities, which affected the relative fractions of the individual pathways, for the photolysis of n-C 4H 9Br near 234 nm and 267 nm. 相似文献
8.
The dimethylphosphino substituted cyclopentadienyl precursor compounds [M(C 5Me 4CH 2PMe 2)], where M=Li + (1), Na + (2), or K + (3), and [Li(C 5H 4CR′ 2PMe 2)], where R′ 2=Me 2 (4), or (CH 2) 5 (5), [HC 5Me 4CH 2PMe 2H]X, where X −=Cl − (6) or PF 6− (7) and [HC 5Me 4CH 2PMe 2] (8), are described. They have been used to prepare new metallocene compounds, of which representative examples are [Fe(η-C 5R 4CR′ 2PMe 2) 2], where R=Me, R′=H (9); R=H and R′ 2=Me 2 (10), or (CH 2) 5 (11), [Fe(η-C 5H 4CMe 2PMe 3) 2]I 2 (12), [Fe{η-C 5Me 4CH 2P(O)Me 2} 2] (13), [Zr(η-C 5R 4CR′ 2PMe 2) 2Cl 2], where R=H, R′=Me (14), or R=Me, R′=H (15), [Hf(η-C 5H 4CMe 2PMe 2) 2]Cl 2] (16), [Zr(η-C 5H 4CMe 2PMe 2) 2Me 2] (17), {[Zr(η-C 5Me 4CH 2PMe 2) 2]Cl}{(C 6F 5) 3BClB(C 6F 5) 3} (18), [Zr{(η-C 5Me 4CH 2PMe 2) 2Cl 2}PtI 2] (19), [Mn(η-C 5Me 4CH 2PMe 2) 2] (20), [Mn{(η-C 5Me 4CH 2PMe 2B(C 6F 5) 3} 2] (21), [Pb(η-C 5H 4CMe 2PMe 2) 2] (23), [Sn(η-C 5H 4CMe 2PMe 2) 2] (24), [Pb{η-C 5H 4CMe 2PMe 2B(C 6F 5) 3} 2] (25), [Pb(η-C 5H 4CMe 2PMe 2) 2PtI 2] (26), [Rh(η-C 5Me 4CH 2PMe 2)(C 2H 4)] 29, [M(η,κ P-C 5Me 4CH 2PMe 2)I 2], where M=Rh (30), or Ir, (31). 相似文献
9.
The directed oligomerization of propene and 1-hexene was carried out with a series of Cp′(C 5H 5)ZrCl 2 and Cp 2′ZrCl 2 pre-catalysts (Cp′=C 5HMe 4, C 4Me 4P, C 5Me 5, C 5H 4tBu, C 5H 3-1,3- tBu 2, C 5H 2-1,2,4- tBu 3) together with (C 5H 5) 2ZrCl 2. Oligomers in the molar mass range 300–1500 g/mol for propene and 200–3000 g/mol for 1-hexene were synthesized at 50 °C. The majority of oligomer molecules contain a double-bond end group. Oligomer characterization was carried out by gel permeation chromatography (GPC), 1H and 13C NMR. Vinylidene double bonds (from β-hydrogen elimination) are solely found for the tert-butyl-substituted zirconocenes and for most of the unsymmetrical methyl-substituted Cp′(C 5H 5)ZrCl 2 systems (except Cp′=phospholyl). With (C 4Me 4P)(C 5H 5)ZrCl 2 and with the symmetrical methyl-containing Cp 2′ZrCl 2 pre-catalysts, also vinyl end groups (from β-methyl elimination) are observed in the case of oligopropenes. The vinylidene/vinyl ratio depends on the ligand and the vinyl content increases from C 5HMe 4 (65/35) over C 4Me 4P (61/39) to C 5Me 5 (9/91). The phospholyl zirconocenes and (C 5HMe 4) 2ZrCl 2 also exhibit chain-transfer to aluminum thereby giving saturated oligomers. 相似文献
10.
In order to understand the nature of the putative cationic 12-electron species [M(η 5:η 1-C 5R 4SiMe 2NR′)R″] + of titanium catalysts supported by a linked amido-cyclopentadienyl ligand, several derivatives with different cyclopentadienyl C 5R 4 and amido substituents R′ were studied systematically. The use of tridentate variants (C 5R 4SiMe 2NCH 2CH 2X) 2− (C 5R 4=C 5Me 4, C 5H 4, C 5H 3tBu; X=OMe, SMe, NMe 2) allowed the NMR spectroscopic observation of the titanium benzyl cations [Ti(η 5:η 1-C 5Me 4SiMe 2NCH 2CH 2X)(CH 2Ph)] +. Isoelectronic neutral rare earth metal complexes [Ln(η 5:η 1-C 5R 4SiMe 2NR′)R″] can be expected to be active for polymerization. To arrive at neutral 12-electron hydride and alkyl species of the rare earth metals, we employed a lanthanide tris(alkyl) complex [Ln(CH 2SiMe 3) 3(THF) 2] (Ln=Y, Lu, Yb, Er, Tb), which allows the facile synthesis of the linked amido-cyclopentadienyl complex [Ln(η 5:η 1-C 5Me 4SiMe 2NCMe 3)(CH 2SiMe 3)(THF)]. Hydrogenolysis of the linked amido-cyclopentadienyl alkyl complex leads to the dimeric hydrido complex [Ln(η 5:η 1-C 5Me 4SiMe 2NCMe 3)(THF)(μ-H)] 2. These complexes are single-site, single-component catalysts for the polymerization of ethylene and a variety of polar monomers such as acrylates and acrylonitrile. Nonpolar monomers such as -olefins and styrene, in contrast, give isolable mono-insertion products which allow detailed studies of the initiation process. 相似文献
11.
Lamellar crystalline calcium phenylphosphonate, as anhydrous Ca(HO 3PC 6H 5) 2 and hydrated Ca(HO 3PC 6H 5) 2·2H 2O compounds, were used as hosts for intercalation of polar n-alkylmonoamine molecules of the general formula CH 3(CH 2) nNH 2 ( n=0–4, 7) in water or 1,2-dichloroethane. An increase in the interlayer distance was observed. The exothermic enthalpic values for intercalation increased with the number of carbon atoms and with increasing concentration of the amines. The intercalation followed by a titration procedure in the solid/liquid interface with Ca(HO 3PC 6H 5) 2·2H 2O and Ca(HO 3PC 6H 5) 2 gave the enthalpy/number of carbons correlations: Δ intH=−(1.74±0.43)–(1.30±0.13) nc and Δ intH=−(4.15±0.15)–(1.07±0.03) nc, for water and 1,2-dichloroethane, respectively. A similar correlation Δ intH=−(4.27±0.80)–(1.85±0.21) nc was obtained in water by using the ampoule breaking procedure for Ca(HO 3PC 6H 5) 2·2H 2O. The increase in exothermic enthalpic values with the increase in n-aliphatic carbon atoms is more pronounced for the anhydrous compound and also when using the ampoule breaking procedure. The Gibbs free energies are negative. Positive entropic values favor intercalation in these systems. 相似文献
12.
The composition of (C 6Me 6)TiAl 2Cl 8−xEt x complexes in (C 6Me 6)TiAl 2Cl 8 + n Et 3Al ( n = 0.5-6) systems was studied by UV-Vis spectroscopy and the X-ray crystal structure of one of them, (η 6-C 6Me 6)Ti[(μ-Cl) 2(AlClEt)] 2 (IIa-2), has been determined. The complex crystallizes in the orthorhombic space group Pna2 1 with Z = 4 and lattice parameters a 15.634(3), b 11.355(2), c 14.417(2) Å. The ethyl groups of IIa-2 reside in outer positions of aluminate ligands farther away from the C 6Me 6 ligand. The other part of the complex does not differ remarkably from structures of other (arene)Ti II complexes. Negligible activity of (C 6Me 6)TiAl 2Cl 8 towards the butadiene cyclotrimerization is considerably increased by addition of 2.5–3.0 equivalents of Et 3Al. As follows from UV-Vis spectra, such systems contain mainly the (C 6Me 6)TiAl 2Cl 5Et 3 complex. It is suggested that the introduction of three Et substituents destabilizes the Ti-(η 6-C 6Me 6) bond so that the replacement of hexamethylbenzene by butadiene in the first step of a catalytic cycle becomes more feasible. 相似文献
13.
Polycrystalline octa-nuclear copper(I) O, O′-di- i-propyl- and O, O′-di- i-amyldithiophosphate cluster compounds, {Cu 8[S 2P(OR) 2] 6(μ 8-S)} where R = iPr and iAm, were synthesized and characterized by 31P CP/MAS NMR at 8.46 T and static 65Cu NMR at multiple magnetic field strengths (7.05, 9.4 and 14.1 T). The symmetries of the electronic environments around the P sites were estimated from the 31P chemical shift anisotropy (CSA) parameters, δaniso and η. Analyses of the 65Cu chemical shift and quadrupolar splitting parameters for these compounds are presented with the data being compared to those for the analogous octa-nuclear cluster compounds with R = nBu and iBu. The 65Cu transverse relaxation for the copper sites in {Cu 8[S 2P(O iPr) 2] 6(μ 8-S)} and {Cu 8[S 2P(O iAm) 2] 6(μ 8-S)} was found to be very different, with a relaxation time, T2, of 590 μs (Gaussian) and 90 μs (exponential), respectively. The structures of {Cu 4[S 2P(O iPr) 2] 4} and {Cu 8[S 2P(O iPr) 2] 6(μ 8-S)} cluster compounds in the liquid- and the solid-state were studied by Cu K-edge EXAFS. The disulfide, [S 2P(O iAm) 2] 2, was obtained and characterized by 31P{ 1H} NMR. The interactions of the disulfide and of the potassium O, O′-di- i-amyldithiophosphate salt with the surfaces of synthetic chalcocite (Cu 2S) were probed using solid-state 31P NMR spectroscopy and only the presence of copper(I) dithiophosphate species with the {Cu 8[S 2P(O iAm) 2] 6(μ 8-S)} structure was observed. 相似文献
14.
The reduction of colourless [LRe VIIO 3]Br in an acetone-water mixture (6: 1) with zinc amalgam affords green, air-sensitive [LRe VO 2Br] which forms a violet complex [LReO(μ-O) 2ReOBr 2]in aqueous solution (L = 1,4,7-triazacyclononane; C 6H 15N 3). From a similar reduction of [LReO 3]ReO 4 the violet neutral complex [LReO(μ-O) 2ReO(ReO 4) 2] was obtained. [LReO 3] + is deprotonated in alkaline solution (p Ka = 10.3 + 0.2, 25°C) and [(C 6H 14N 3)ReO 3] was isolated as a yellow solid. The latter amido rhenium(VII) compound reacted in dimethylformamide with R---X (R = CH 3, benzyl; X = Cl), affording at the cyclic amine, N,N′,N″-trisalkylated complexes of the type [L′ReO 3]X. The monomeric rhenium(V) complexes [LReOX 2]X (X = Cl, Br, I) were obtained from the reaction of [ n-Butyl 4N]ReOX 4 and L in acetonitrile. IR, UV-vis, 17O NMR spectra of these compounds are reported. 相似文献
15.
The reaction of the anionic mononuclear rhodium complex [Rh(C 6F 5) 3Cl(Hpz)] t- (Hpz = pyrazole, C 3H 4N 2) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C 6F 5) 3Rh(μ-Cl)(μ-pz)M(L 2)] [M = Rh, L 2 = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO) 2 (4); M = Ir, L 2 = COD (3)]. The complex [Rh(C 6F 5) 3(Hbim)] − (5) has been prepared by treating [Rh(C 6F 5) 3(acac)] − with H 2bim (acac = acetylacetonate; H 2bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C 6F 5) 3Rh(μ-bim)M(L 2)] − [M = Rh, L 2 = COD (6) or TFB (7); M = Ir, L 2 = COD (8); M = Pd, L 2 = η 3-C 3H 5 (9)]. With [Rh(acac)(CO) 2], complex 5 yields the tetranuclear complex [{(C 6F 5) 3Rh(μ-bim)Rh(CO) 2} 2] 2−. Homodinuclear Rh III derivatives [{Rh(C 6F 5) 3} 2(μ-L) 2] ·- [L 2 = OH, pz (11); OH, S tBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C 6F 5) 3(μ-OH)} 2] 2− by the corresponding ligands. The reaction of [Rh(C 6F 5) 3(Et 2O) x] with [PdX 2(COD)] produces neutral heterodinuclear compounds [(C 6F 5) 3Rh(μ-X) 2Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh 3+) salts. 相似文献
16.
By use of the three-layer diffusion method, reactions of flexible bipyridyl ligands (4,4′-bpp or 3,3′-bpp) with M(II) salts (M = Zn, Cd) and multi-carboxylate ligands resulted in the formation of four interesting d 10 metal–organic coordination polymers: [Zn(μ-4,4′-bpp)Br 2] n (1), [Zn(μ-4,4′-bpp)(1,2-bdc)] n · nH 2O (2), [Zn(μ-3,3′-bpp)(1,3-bdc)] n · nCH 3OH · 2 nH 2O (3) and [Cd(μ-3,3′-bpp)(C 4H 2O 4)] n · 3 nH 2O (4) (4,4′-bpp = 2,2′-bis(4-pyridylmethyleneoxy)-1,1′-biphenylene; 3,3′-bpp = 2,2 ′-bis(3-pyridylmethyleneoxy)-1,1′-biphenylene; bdc=benzenedicarboxylate, C 4H 4O 4 = fumaric acid). Complex 1 has a 2D sheet structure consisting of two unusual zigzag Zn(II) chains which are nearly perpendicular to each other. Complex 2 is comprised of two-leg ladders, in which [Zn(4,4′-bpp)] chains serve as the side rails and 1,2-bdc ligands serve as the cross rungs. In complex 3, every two 1,3-bdc ligands connect the neighbouring Zn(II)-3,3′-bpp dimetallic rings in η 1 coordination modes into an interesting chain structure. Complex 4 consists of an anionic macrocycle-containing cadmium dicarboxylate sheets that are separated by 3,3′-bpp. These d 10 metal complexes exhibit high thermal stabilities and strong luminescence efficiencies. 相似文献
17.
A series of novel heterobimetallic crown ether-like polyoxadiphosphaplatinaferrocenophanes cis-[1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2PPh 2) 2]PtCl 2 ( n=1–3) (4a–c) was synthesized in good yield by cyclization of the bis(phosphine) ligands 1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2PPh 2) 2 ( n=1–3) (3a–c) and (PhCN) 2PtCl 2 under high dilution conditions in CH 2Cl 2. The bisphosphines 3a–c are obtained by reaction of the corresponding diols 1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2OH) 2 ( n=1–3) (1a–c) with: (i) CH 3SO 2Cl in CH 2Cl 2 and (ii) LiPPh 2 in THF. Although the X-ray crystal structure of 4a shows that the cavity is large enough for the encapsulation of small metal cations, inclusion experiments of 4a–c with Group 1 cations, and Mg 2+, or NH 4+ in solution applying NMR titration and cyclovoltammetric methods reveal no evidence for the formation of host–guest complexes for 4a,b. In the case of 4c only the addition of Na + or K + leads to an insignificant effect. 相似文献
18.
In the present theoretical work we have explored mechanisms of dissociation reactions of the vinyl radical in the A 2A″ state (C 2H 3 (A 2A″)) and examined possible pathways for nonadiabatic dissociation of C 2H 3 (A 2A″) into C 2H 2 (X 1Σ g+). In the calculations we used the complete active space self-consistent field (CASSCF) and multiconfiguration second-order perturbation theory (CASPT2) methods in conjunction with the cc-pVDZ and cc-pVTZ basis sets. Mechanisms for the following three dissociation channels of C 2H 3 in the A 2A″ state were explored: (1) C 2H 3 (A 2A″) → C 2H 2 ( trans, 3A u) + H, (2) C 2H 3 (A 2A″) → C 2H 2 ( cis, 3A 2) + H, and (3) C 2H 3 (A 2A″) → H 2CC ( 3A 2) + H. The CASSCF and CASPT2 potential energy curve calculations for the C 2H 3 (A 2A″) dissociation channels (1)–(3) indicate that there is neither transition state nor intermediate for each of the channels. At the CASPT2//CASSCF/cc-pVTZ level, the dissociation energies for channels (1)–(3) are predicted to be 84.3, 91.1, and 86.9 kcal/mol, respectively. For a recently observed nonadiabatic dissociation of C 2H 3 (A 2A″) into C 2H 2 (X 1Σ g+) + H [J. Chem. Phys. 111 (1999) 3783], two previously suggested internal conversion (IC) pathways were examined based on our CASSCF and CASPT2 calculations. Our preliminary CASSCF and CASPT2 calculations indicate that the assumed IC pathway via the twisted C 2H 3 (A 2A ′) structure might be feasible. The CASSCF/cc-pVTZ geometry optimization and frequency analysis calculations were performed for the four C 2v bridge structures in the 2B 2, 2A 2, 2B 1, and 2A 1 states along the pathways of the 1 2A ′ (X 2A ′), 1 2A″ (A 2A″), 2 2A″, and 2 2A ′ states of C 2H 3, respectively, and the CASPT2//CASSCF/cc-pVTZ energetic results indicate that the assumed IC pathway, via a C 2v ( 2A 2) structure and then 2A 2/ 2A 1 surface crossing, be not feasible since at their excitation wavelengths (327.4 and 366.2 nm) the C 2v ( 2A 2) structure could not be accessed. 相似文献
19.
The reactions of RNHSi(Me) 2Cl (1, R= t-Bu; 2, R=2,6-(Me 2CH) 2C 6H 3) with the carborane ligands, nido-1-Na(C 4H 8O)-2,3-(SiMe 3) 2-2,3-C 2B 4H 5 (3) and Li[ closo-1-R′-1,2-C 2B 10H 10] (4), produced two kinds of neutral ligand precursors, nido-5-[Si(Me) 2N(H)R]-2,3-(SiMe 3) 2-2,3-C 2B 4H 5, (5, R= t-Bu) and closo-1-R′-2-[Si(Me) 2N(H)R]-1,2-C 2B 10H 10 (6, R= t-Bu, R′=Ph; 7, R=2,6-(Me 2CH) 2C 6H 3, R′=H), in 85, 92, and 95% yields, respectively. Treatment of closo-2-[Si(Me) 2NH(2,6-(Me 2CH) 2C 6H 3)]-1,2-C 2B 10H 11 (7) with three equivalents of freshly cut sodium metal in the presence of naphthalene produced the corresponding cage-opened sodium salt of the “carbons apart” carborane trianion, [ nido-3-{Si(Me) 2N(2,6-(Me 2CH) 2C 6H 3)}-1,3-C 2B 10H 11] 3− (8) in almost quantitative yield. The reaction of the trianion, 8, with anhydrous MCl 4 (M=Ti and Zr) in 1:1 molar ratio in dry tetrahydrofuran (THF) at −78 °C, resulted in the formation of the corresponding half-sandwich neutral d 0-metallacarborane, closo-1-M[(Cl)(THF) n]-2-[1′-η 1σ-N(2,6-(Me 2CH) 2C 6H 3)(Me) 2Si]-2,4-η 6-C 2B 10H 11 (M=Ti (9), n=0; M=Zr (10), n=1) in 47 and 36% yields, respectively. All compounds were characterized by elemental analysis, 1H-, 11B-, and 13C-NMR spectra and IR spectra. The carborane ligand, 7, was also characterized by single crystal X-ray diffraction. Compound 7 crystallizes in the monoclinic space group P2 1/ c with a=8.2357(19) Å, b=28.686(7) Å, c=9.921(2) Å; β=93.482(4)°; V=2339.5(9) Å 3, and Z=4. The final refinements of 7 converged at R=0.0736; wR=0.1494; GOF=1.372 for observed reflections. 相似文献
20.
Distibines of the type R 2SbSbR′ 2 with R = CH 3, R′ = C 2H 5 (1), R = CH 3, R′= n-C 3H 7 (2), R = CH 3, R′= C 6H 5 (3), R = C 2H 5, R′= C 6H 5 (4), R = n-C 3H 7, R′ = C 6H 5 (5), and R = CH 3, R′ = 2,4,6-(CH 3) 2C 6H 2 (6) are formed in equilibria by exchange reactions of the respective distibines of the type R 4Sb 2 and R′ 4Sb 2. 相似文献
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