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1.
Contributions to the Chemistry of Silicon-Sulphur Compounds. XXIX. 29Si-N.M.R. Investigations Three series of silicon-sulphur compounds (RO)3SiSR′ (I), (i-PrO)4?nSi(SEt)n (II) and cyclic Si? S compounds (III) were prepared, some of them at the first time and their 29Si-N.M.R. spectra were measured. In the series of trialkoxysilylthio derivatives (I) were the steric and inductive effects of the RO and R'S groups evaluated. In the series II were the 29Si-N.M.R. chemical shifts related to the relative paramagnetic screening constants σ* and netto charge at the silicon atom q(Si) using the EN-quantum-chemical model discussed. In the series III were the shift contribution of the (SiS)2 and 1-sila-2,5-dithiacyclopentan rings determined. 相似文献
2.
Contributions to the Chemistry of Silicon-Sulphur Compounds. 44. Trialkoxysilylthio Derivatives of Permethylpolysilanes By reaction of (RO)3SiSH · NEt3 (R = i-Pr, t-Bu) with α,ω-Cl2(SiMe2)n (n = 1, 2, 3, 4, 6) or with 1-Cl(SiMe2)nMe (n = 2, 4) trialkoxysilylthio derivatives of polysilanes of the two series α,ω-(RO)3SiS(SiMe2)nSSi(OR)3 and 1-(RO)3SiS(SiMe2)nMe have been prepared. Some properties of obtained new compounds were given. The resistance of the Si? S bond on protolytic splitting has been characterized by half-life times of the alcoholysis reaction. 相似文献
3.
29Si, 13C and 1H NMR spectra are reported for the series of linear permethylpolysilanes Me(SiMe2)nMe where n = 1 to 6, for the cyclic permethylpolysilanes (Me2Si)n where n = 5 to 8, and for a few related compounds. For linear polysilanes the 29Si and 13C chemical shifts can be accurately calculated from simple additivity relationships based on the number of silicon atoms in α, β, γ and δ positions. Adjacent (α) silicon atoms lead to upfield shifts in the 29Si and 13C resonances, whereas more remote silicon atoms lead to downfield shifts. The 29Si chemical shifts of the polysilane chains are linearly related to the 13C shifts of the carbon atoms attached to the silicon. The 29Si and 13C resonances of the cyclic silanes deviate from this relationship. Ring current effects arising from σ delocalization are suggested as an explanation for the deviations. Proton-coupled 29Si NMR spectra are reported for Me3SiSiMe3 and for (Me2Si)n, n = 5 to 7. 相似文献
4.
Spectroscopic Investigations on Substituent Effects in Silylmethylsilanes The silanes Me3?n(Me3SiCH2)nSiH (n = 1–3), (RMe2SiCH2)3SiH (R = n-Bu, n-Pr, Et, PhCH2, Ph) and Me3ElCH2SiMe2H (El = Ge, Sn) were prepared. The frequencies of the Si? H stretching vibration, the 29Si? 1H coupling constants and the 29Si n.m.r. chemical shifts were measured. The ?(SiH) and J(29Si? 1H) values in the silanes Me3?n(Me3SiCH2)nSiH depend on the number of trimethylsilymethyl groups. There is hardly an influence of the substituents R on these values in the silanes (RMe2SiCH2)3SiH. The frequencies of the Si? H stretching vibrations in the silanes Me3ElCH2SiMe2H (El = Si, Ge, Sn) show the order Si?Ge > Sn. The 29Si n.m.r. chemical shifts of the Si(H) signals are approximately equal in the silanes Me3?n(Me3SiCH2)nSiH and (RMe2SiCH2)3SiH. 相似文献
5.
29Si Chemical Shifts of Alkoxy(amino)silanes The 29Si NMR spectra of a series of alkoxy(amino)silanes (RO)nMe3?nSiNHC6H4X (n = 1–3) have been measured and are discussed by means of relative paramagnetic screening constants σ*, calculated by a simplified quantum-chemical model. The Hammett plots of the silicon chemical shift show both positive and negative slopes with changes of the number of electronegative atoms (O, N) attached to silicon. The steric and electronic shift contributions of the alkoxy groups are given. 相似文献
6.
《Mendeleev Communications》2022,32(5):686-687
Novel N-isopropyl-N',N'-dimethyl-N-(silylmethyl)ureas Me2NC(O)N(Pri)CH2SiMenX3–n (X = OEt, F; n = 0–2) were synthesized, and their structure was confirmed by 1H, 13C and 29Si NMR spectroscopy. According to NMR data, the silicon atom of the fluorosilanes (X = F) is pentacoordinated. The X-ray diffraction analysis of the (trifluorosilyl)methylcontaining urea showed that it exists as (O–Si) chelate with intramolecular dative bond C=O→Si (1.880 Å). 相似文献
7.
Electronic and Steric Effects in 29Si N.M.R. Spectra of Amino-substituted Silanes Compounds of three series of amino-substituted silanes, MenSi(NR′R″)4—n′, Me3-n (RO)nSiNR′R″, and (RO)nSi(NR′R″)4—n, (n = 0 ÷ 3), were prepared and characterized. 29Si N.M.R. spectra have been measured. The electronic and steric shift contributions of the NR′R″ groups are given and discussed on the basis of a quantum-chemical model. The mass spectra also have been recorded and the fragmentation schemes for silanes multi substituted with amino groups are presented. 相似文献
8.
Neutral Rearrangement between Boryl and Silyl Groups in B-Halogenosubstituted Boryl-bis(silyl)hydroxylamines Dihalogenboranes, RBX2, react with lithiated N,O-Bis(trimethylsilyl)hydroxylamine to give B-halogeno-borylhydroxylamines RB(X)ON(SiMe3)2: X = F, R = Trip (Trip = 2,4,6-triisopropylphenyl) ( I a ), N(SiMe3)2 ( I b ), N(CHMe2)2 ( I c ), N(SiMe3)Dip (Dip = 2,6-diisopropylphenyl) ( I d ) and X = Cl, R = N(SiMe3)2 ( I e ). Depending upon the substituents on the boron atom a dyotropic rearrangement can be effected which transforms the compounds I a , I b und I e into the isomeric borylhydroxylamines RB(X)N(SiMe3)OSiMe3 II a , II b and II e . The compounds are characterized by their m. s. and n. m. r. (1H, 11B, 13C, 19F, 29Si) spectra and by elemental analyses. 相似文献
9.
Preparation, Characterization and Reaction Behaviour of Sodium and Potassium Hydridosilylamides R2(H)Si—N(M)R′ (M = Na, K) — Crystal Structure of [(Me3C)2(H)Si—N(K)SiMe3]2 · THF The alkali metal hydridosilylamides R2(H)Si—N(M)R′ 1a‐Na — 1d—Na and 1a‐K — 1d‐K ( a : R = Me, R′ = CMe3; b : R = Me, R′ = SiMe3; c : R = Me, R′ = Si(H)Me2; d : R = CMe3, R′= SiMe3) have been prepared by reaction of the corresponding hydridosilylamines 1a — 1d with alkali metal M (M = Na, K) in presence of styrene or with alkali metal hydrides MH (M = Na, K). With NaNH2 in toluene Me2(H)Si—NHCMe3 ( 1a ) reacted not under metalation but under nucleophilic substitution of the H(Si) atom to give Me2(NaNH)Si—NHCMe3 ( 5 ). In the reaction of Me2(H)Si—NHSiMe3 ( 1b ) with NaNH2 intoluene a mixture of Me2(NaNH)Si—NHSiMe3 and Me2(H)Si—N(Na)SiMe3 ( 1b‐Na ) was obtained. The hydridosilylamides have been characterized spectroscopically. The spectroscopic data of these amides and of the corresponding lithium derivatives are discussed. The 29Si‐NMR‐chemical shifts and the 29Si—1H coupling constants of homologous alkali metal hydridosilylamides R2(H)Si—N(M)R′ (M = Li, Na, K) are depending on the alkali metal. With increasing of the ionic character of the M—N bond M = K > Na > Li the 29Si‐NMR‐signals are shifted upfield and the 29Si—1H coupling constants except for compounds (Me3C)(H)Si—N(M)SiMe3 are decreased. The reaction behaviour of the amides 1a‐Na — 1c‐Na and 1a‐K — 1c‐K was investigated toward chlorotrimethylsilane in tetrahydrofuran (THF) and in n‐pentane. In THF the amides produced just like the analogous lithium amides the corresponding N‐silylation products Me2(H)Si—N(SiMe3)R′ ( 2a — 2c ) in high yields. The reaction of the sodium amides with chlorotrimethylsilane in nonpolar solvent n‐pentane produced from 1a‐Na the cyclodisilazane [Me2Si—NCMe3]2 ( 8a ), from 1b‐Na and 1‐Na mixtures of cyclodisilazane [Me2Si—NR′]2 ( 8b , 8c ) and N‐silylation product 2b , 2c . In contrast to 1b‐Na and 1c‐Na and to the analogous lithium amides the reaction of 1b‐K and 1c‐K with chlorotrimethylsilane afforded the N‐silylation products Me2(H)Si—N(SiMe3)R′ ( 2b , 2c ) in high yields. The amide [(Me3C)2(H)Si—N(K)SiMe3]2·THF ( 9 ) crystallizes in the space group C2/c with Z = 4. The central part of the molecule is a planar four‐membered K2N2 ring. One potassium atom is coordinated by two nitrogen atoms and the other one by two nitrogen atoms and one oxygen atom. Furthermore K···H(Si) and K···CH3 contacts exist in 9 . The K—N distances in the K2N2 ring differ marginally. 相似文献
10.
Yi-Ming Pai William P. Weber Kenneth L. Servis 《Journal of organometallic chemistry》1985,288(3):269-273
29Si NMR spectra of polymethylhydrosiloxanes, Me3SiO[MeHSiO]nSiMe3 from n = 3 to 8 and 35, have been determined. Both chemical shifts and spin-lattice relaxation times (T1) have been measured. The stereochemistry at the adjacent chiral MeHSiO unit influences the nearest neighbor 29Si chemical shift. The effect of chain length and position of MeHSiO units on T1 values for Me3SiO[MeHSiO]nSiMe3 systems are discussed. 相似文献
11.
Reactions of Lithium Hydridosilylamides RR′(H)Si–N(Li)R″ with Chlorotrimethylsilane in Tetrahydrofuran and Nonpolar Solvents: N‐Silylation and/or Formation of Cyclodisilazanes The lithiumhydridosilylamides RR′(H)Si–N(Li)R″ ( 2 a : R = R′ = CHMe2, R″ = SiMe3; 2 b : R = R′ = Ph, R″ = SiMe3; 2 c : R = R′ = CMe3, R″ = SiMe3; 2 d : R = R′ = R″ = CMe3; 2 e : R = Me, R′ = Si(SiMe3)3, R″ = CMe3; 2 f – 2 h : R = R′ = Me, f : R″ = 2,4,6‐Me3C6H2, g : R″ = SiH(CHMe2)2, h : R″ = SiH(CMe3)2; 2 i : R = R′ = CMe3, R″ = SiH(CMe3)2) were prepared by reaction of the corresponding hydridosilylamines RR′(H)Si–NHR″ 2 a – 2 i with n‐butyllithium in equimolar ratio in n‐hexane. The unknown amines 1 e – 1 i and amides 2 f – 2 i have been characterized spectroscopically. The wave numbers of the Si–H stretching vibrations and 29Si–1H coupling constants of the amides are less than of the analogous amines. This indicates a higher hydride character for the hydrogen atom of the Si–H group in the amide in comparison to the amines. The 29Si‐NMR chemical shifts lie in the amides at higher field than in the amines. The amides 2 a – 2 c and 2 e – 2 g react with chlorotrimethylsilane in THF to give the corresponding N‐silylation products RR′(H)Si–N(SiMe3)R″ ( 3 a – 3 c , 3 e – 3 g ) in good yields. In the reaction of 2 i with chlorotrimethylsilane in molar ratio 1 : 2,33 in THF hydrogen‐chlorine exchange takes place and after hydrolytic work up of the reaction mixture [(Me3C)2(Cl)Si]2NH ( 5 a ) is obtained. The reaction of the amides 2 a – 2 c , 2 f and 2 g with chlorotrimethylsilane in m(p)‐xylene and/or n‐hexane affords mixtures of N‐substitution products RR′(H)Si–N(SiMe3)R″ ( 3 a – 3 c , 3 f , 3 g ) and cyclodisilazanes [RR′Si–NR″]2 ( 6 a – 6 c , 6 f , 6 g ) as the main products. In case of the reaction of 2 h the cyclodisilazane 6 h was obtained only. 2 c – 2 e show a very low reactivity toward chlorotrimetyhlsilane in m‐xylene and toluene resp.. In contrast to Me3SiCl the reactivity of 2 d toward Me3SiOSO2CF3 and Me2(H)SiCl is significant higher. 2 d react with Me3SiOSO2CF3 and Me2(H)SiCl in n‐hexane under N‐silylation to give RR′(H)Si–N(SiMe3)R″ ( 3 d ) and RR′(H)Si–N(SiHMe2)R″ ( 3 d ′) resp. The crystal structures of [Me2Si–NSiMe3]2 ( I ) ( 6 f , 6 g and 6 h ) have been determined. 相似文献
12.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1993,49(2):161-165
The structure and 29Si chemical shifts of the halodimethylsilylnonamethylcyclopentasilanes Si5Me9SiMe2X (1–4) and the halononamethylcyclopentasilanes Si5Me9X (5–8) (X = F, Cl, Br, I) have been assigned using 1J(SiSi) and 2J(SiSi) coupling constants derived from 29Si-INADEQUATE and 29Si-INEPT—INADEQUATE NMR spectra. The compounds exhibit good correlation between chemical shift, 1J(SiSi) and Pauling electronegativities. 相似文献
13.
Basicity and 29Si N.M.R. Spectroscopic Investigations of Ethoxysiloxanes Ethoxysiloxanes of the types (RMe2SiO)3SiOEt, Me3?n(R3SiO)nSiOEt, [(Me3SiO)3SiO]n(Me3SiO)3?nSiOEt (n = 1–3), and (Me3SiO)3Si[OSi(OSiMe3)2]2OEt have been prepared. The relative basicity of the (Si)OEt group and the 29Si n.m.r. chemical shifts of the Si(OEt) signal were determined. The relative basicity as well as the 29Si n.m.r. chemical shifts depend on the kind and number of the siloxy groups. Basicity and 29Si n.m.r. chemical shifts of the respective types of compounds are connected directly with each other. 相似文献
14.
Contributions to the Chemistry of Silicon-Sulphur Compounds. XLIII. Alcoholysis Reaction of Silicon-Sulphur Compounds with Alkoxyethanols and 2-Mercaptoethanol The reactions of 2-alkoxyethanols und 2-mercaptoethanol with (RO)3SiSH, (RO)2Si(SH)2, cyclo-[(t-BuO2)SiS]2, and SiS2 were investigated. Besides of mixed esters of orthosilicic acid a new group of mixed trialkoxysilanethiols – (RO)2(R′O)SiSH – was obtained. Informations about the hydrolytic splitting of the Si? S bond of these Si? S compounds were obtained by thiomercurimetric titration with HMB. 相似文献
15.
29Si and 13C NMR spectra are reported for the three halopolysilane series Me(SiMe2)nCl, Cl(SiMe2)nCl and F(SiMe2)nF, where n = 2 to 6. Except for the dihalodisilanes (XSiMe2)2, data for all of the compounds fit linear relationships based on substituent constants for chlorine or fluorine atoms in the α, β and γ positions. The effects of halogen substitution on 29Si and 13C chemical shifts are rapidly attenuated along the polysilane chain, becoming negligible four atoms away from the halogen. The NMR data provide no evidence for long-range electronic transmission from chlorine or fluorine in halopermethylpolysilanes of the type suggested by other workers [1]. 相似文献
16.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1988,44(7):643-646
Silicon-29(δ29Si) NMR chemical shifts are reported for the first time of tris[(trimethylsilyl)methyl] silicon compounds (disilylated derivatives) (Me3SiA)3 CαL, where L = SiBR1R2R3 and where R varies widely in electronegativity. 29Si chemical shifts exhibit good correlation with the electronegativities of the groups bonded to the silicon atom. The 13C NMR spectra of these compounds have been recorded and assigned. δ13Cα is shown to depend on the type of substitutent on SiB. The variation of 29SiH coupling constants with electronegativity of R is studied. 相似文献
17.
Isomeric mixtures of compounds MenM(CH?CHMe)4?n (M=Si, Pb; n=0?3) have been prepared and studied, as well as pure Me3M(CMe?CH2) and mixtures containing propenyl isopropenyl residues bonded to silicon and lead. 1H, 13C, 29Si and 207Pb NMR data are presented; as previously observed for the corresponding tin compounds, the 29Si and 207Pb shifts for the Me3MC3H5 isomers can be used to calculate the shifts expected for the other isomers; while for lead the agreement is good, calculated and observed values for silicon diverge with decreasing n due, at least in part, to steric factors. 相似文献
18.
New Alkali Metal Coordinations by Chelating Siloxazane Units within Molecules of the General Formula [X–N–SiMe2–O–SiMe2–N–X]2M4 New solvent free alkali metal amides with Si–O–Si bridges of the general formula [X–N–SiMe2–O–SiMe2–N–X]2M4 (X = tBu ( 1 ), SiMe3 ( 2 ), SiMe2tBu ( 3 ) with M = Li; X = tBu ( 4 ), SiMe3 ( 5 ) with M = Na; X = tBu mit M = K, Li ( 6 )) have been synthesised and characterised by spectroscopic means. X‐ray structure analyses of the six metal derivatives reveal a common structural principle: the four metal atoms within the molecules are incorporated between two molecular halfs and form the bonding links between the two parts. The central molecular skeleton of the molecular halfs consists of a zig‐zag chain N–Si–O–Si–N. This chain is connected to the second one either ideally or approximately by S4 (4) symmetry. The point symmetries within the crystal are either S4 (4) (compounds 2 and 4 ), C2 (2) (compound 6 ), and C1 (1) (compounds 3 and 5 ). Compound 1 is special in different aspects: the molecule has the high crystallographic point symmetry D2d (4m2) and the lithium atoms occupy split atom positions (in a similar way as in compound 2 ). The high symmetry of 1 as well as the split atom positions of the lithium atoms are a consequence of dynamics within the crystal. 相似文献
19.
Paul Ronald Jones Todd E Albanesi Ralph D Gillespie Priscilla C Jones Seik Weng Ng 《应用有机金属化学》1987,1(6):521-528
Six bis(silyl)acetylenes (XMe2Si? C?C? SiMe2X) with the following varied silicon substituents X were prepared: 1 (Me, Me); 2 (H, H); 3 (C1, H); 4 (CI, CI); 5 (MeO, H); 6 (MeO, MeO). While 1 and 2 may be prepared by the reaction of dilithio- or bis(bromomagnesium)-acetylide with the appropriate chlorosilane, similar reactions designed to give 3–6 yielded oligomers, XMe2Si? (? C?C? SiMe2)n? X, 7, X=CI, MeO, as the major products, indicating that the acetylenic functionality on silicon activates the chlorosilane towards nucleophilic substitution. Compounds 3 and 4 were prepared by free radical chlorination of 2. Methanolysis of 3 and 4 gave quantitative yields of 5 and 6 respectively. Compounds 1–6 undergo a Diels–Alder reaction with α-pyrone to produce, after loss of carbon dioxide, bis(silyl)-substituted benzene derivatives. The order of reactivity has been determined to be: 4=6>3=5>1>2, indicating that chloro or alkoxy substituents favor the cycloaddition with 2- pyrone. The adducts formed by compounds 3–6 undergo an unusually facile hydrolysis or elimination to give 1,1,3,3-tetramethyl-1,3-disila-2-oxaindane. 相似文献
20.
Preparation and Spectroscopic Investigations of Highly Branched Functional Siloxanes The preparation of the siloxanes [(Me3SiO)3SiO]n(Me3SiO)3?nSiX and (Me3SiO)3Si[OSi(OSiMe3)2]2X (n = 1?3, X = H, Cl, OC2H5, OH) is described. The hydride-siloxanes and the siloxanoles have been investigated by i.r. and 29Si-n.m.r. spectroscopy. The frequencies of the Si? H stretching vibration, the 29Si? 1H coupling constants and the 29Si-chemical shifts of the Si(H) signal for the hydride-siloxanes as well as the frequencies of the (Si)O? H stretching vibration, the relative (Si)O? H acidity, and the 29Si-chemical shifts of the Si(OH) signal for the siloxanoles show a dependence on the number of the (Me3SiO)3SiO groups. The spectroscopic data are discussed with respect to the silicate environment of the Si(H) and Si(OH) atom, respectively. In the siloxanoles intramolecular hydrogen bondings were observed. 相似文献