Hg2(CH3SO3)2: Synthese,Kristallstruktur, thermisches Verhalten und Schwingungsspektroskopie

Hg₂(CH₃SO₃)₂: Synthesis, Crystal Structure, Thermal Behavior, and Vibrational Spectroscopy Colorless single crystals of Hg₂(CH₃SO₃)₂ are formed in the reaction of HgO, Hg, and HSO₃CH₃. In the monoclinic compound (I2/a, Z = 4, a=883.2(2), b=854.0(2), c=1188.9(2) pm, β = 92.55(2)°, R_all=0.0445) the Hg₂²⁺ ion is coordinated by two monodentate CH₃SO₃^— anions. Further contacts Hg‐O occur in the range from 262 to 276 pm and lead to a linkage of the [Hg₂(CH₃SO₃)₂] units. The thermal analysis shows that Hg₂(CH₃SO₃)₂ decomposes at 300° yielding elemental mercury. The mass numbers of the species evolved lead to the assumtion that SO₃, SO₂, CO₂, CO and H₂CO are formed during the reaction. In the IR and the Raman spectrum the typical vibrations of the CH₃SO₃^— ion are observed, the Raman spectrum shows the Hg‐Hg stretching vibration at 177 cm^—1 within the Hg₂²⁺ ion additionally.     

Die Kristallstruktur von [InI · C6D6][{(CH3)3Si}3C‐InI3]; ein Nebenprodukt der Umsetzung von InI3 mit basefreiem Li‐C(Si(CH3)3)3

The title compound is formed together with Li[Tsi‐InI₃] (the main product), (Tsi‐In(Me)I)₂ and (Tsi)₂InMe in very low yield in the reaction of InI₃ with Tsi‐Li (Tsi = ‐C(Si(CH₃)₃)₃)in toluene. According to the X‐ray structure determination this compound crystallizes in the triclinic space group P&1marc; and consists of slightly associated dimers of [Tsi‐InI₃]^‐ anions via weak In^I···I(‐In^III) contact‐bonds of 345.6(1) to 373.8(2) pm. Additionally the In^I atom is capped by a D₆‐benzene molecule.     

Interpretation der Schwingungsspektren von (CH3)2SO2, (CH3)2SO(NH) und (CH3)2S(NH)2 unter Verwendung eines Kopplungsstufenverfahrens

Normal Coordinate Analysis of (CH₃)₂SO₂, (CH₃)₂SO(NH), and (CH₃)₂S(NH)₂ using the Method of Stepwise Coupling The qualitative assignment of the vibrational spectra of (CH₃)₂SO₂ ( 1 ), (CH₃)₂SO(NH) ( 2 a ), and (CH₃)₂S(NH)₂ ( 3 a ) and of the C and N deuterated derivatives of 2 a and 3 a is used in a normal coordinate analysis by the method of stepwise coupling. The force constants and the energy distributions are calculated in symmetry coordinates using a generalized valence force field.     

Synthesis of sulphonated aminomethylphosphines and some nickel(II), palladium(II), platinum(II) and rhodium(I) complexes. Crystal structure of [Et3NH][(Ph2PCH2)2 N(CH2)2SO3]

Summary Aminoalkanesulphonic acids H₂N(CH₂) _n SO₃H, (n = 1, 2 or 3) react with phosphonium salts [R₂P(CH₂OH)₂]Cl (R = Ph or Cy, Cy = cyclohexyl) in the presence of Et₃N to give the sulphonated aminomethylphosphines [Et₃NH] [(R₂PCH₂)₂N(CH₂) _n SO₃] (R = Ph, n = 1, 2 or 3; R = Cy, n = 1). The single crystal X-ray structure of [Et₃NH] [(Ph₂PCH₂)₂N(CH₂)₂SO₃] has been determined. Some Ni^II, Pd^II, Pt^II and Rh^I complexes of the phosphines have been prepared.     

Dimethylarsenazid (CH3)2AsN3, Dimethylwismutazid (CH3)2BiN3 und Dimethylthalliumzid (CH3)2TiN3

The reaction of (CH₃)₂AsJ and AgN₃ yields (CH₃)₂AsN₃; a colourless liquid (b. p. 136°C) which dissolves as a monomeric in benzene. (CH₃)₂BiN₃ is precipitated in form of colourless needles (dec. temp. 150°C) from an etherical solution of Bi(CH₃)₃ and HN₃. According to its vibrational and mass spectra the molecules are not associated although the (CH₃)₂BiN₃ is not soluble; dipole association of this polar molecules is assumed for the crystal structure. (CH₃)₂TlN₃ can be obtained from TI(CH₃)₃ and ClN₃ as well as from (CH₃)₂TlOH and HN₃ in form of colourless needles and leaves (dec. temp. 245°C). According to its vibrational spectra it has an ionic structure, (CH₃? Tl? CH₃)⁺N^?₃.     

[{(CH3)3Si}3C–Li–C{Si(CH3)3}3][Li · 3(OC4H8)] und {(CH3)3Si}3C–Li · O=C(Si(CH3)3)2, zwei neue Addukte des Lithium‐trisylmethanids

[{(CH₃)₃Si}₃C–Li–C{Si(CH₃)₃}₃][Li · 3(OC₄H₈)] and {(CH₃)₃Si}₃C–Li · O=C(Si(CH₃)₃)₂, two New Adducts of Lithium Trisylmethanide Sublimation of (Tsi–Li) · 2 THF (Tsi = –C(Si(CH₃)₃)₃) at 180 °C and 10^–4 hPa gives (Tsi–Li) · 1.5 THF in very low yield. The X‐ray structure determination shows an almost linear [Tsi–Li–Tsi]^– anion connected by short agostic Li…C contacts with the threefold THF‐coordinated Li‐cation. Base‐free Tsi–Li, solved in toluene is decomposed by oxygen, forming the strawberry‐colored ketone O=C(SiMe₃)₂, which forms an 1 : 1 adduct with undecomposed Tsi–Li. The X‐ray structure elucidation of this compound is also discussed.     

Dodecaindane (tBu3Si)8In12—A Compound with an In12 Deltapolyhedron Framework

A unique feature among polyhedron frameworks of boron group elements is exhibited by the In₁₂ framework of the black-violet dodecaindane R^*₈In₁₂ (R*=SitBu₃), which can be obtained by the thermolysis of R^*₂In−InR^*₂. The molecular structure of R^*₈In₁₂ (tBu groups omitted in picture shown) can be described as a combination of two R^*₄In₆ octahedral building blocks and can thus be classified as a conjuncto dodecaindane.     

Über Bildung und Reaktionen der CH2Li‐Derivate von tBu2P–P=P(CH3)tBu2 und (Me3Si)tBuP–P=P(CH3)tBu2

Formation and Reactions of the CH₂Li‐Derivatives of ^tBu₂P–P=P(CH₃)^tBu₂ and (Me₃Si)^tBuP–P=P(CH₃)^tBu₂ With ⁿBuLi, (Me₃Si)^tBuP–P=P(CH₃)^tBu₂ ( 1 ) and ^tBu₂P–P=P(CH₃)^tBu₂ ( 2 ) yield (Me₃Si)^tBuP–P=P(CH₂Li)^tBu₂ ( 3 ) and ^tBu₂P–P=P(CH₂Li)^tBu₂ ( 4 ), wich react with Me₃SiCl to give (Me₃Si)^tBuP–P=P(CH₂–SiMe₃)^tBu₂ ( 5 ) and ^tBu₂P–P=P(CH₂–SiMe₃)^tBu₂ ( 6 ), respectively. With ^tBu₂P–P(SiMe₃)–P^tBuCl ( 7 ), compound 3 forms 5 as well as the cyclic products [H₂C–P(^tBu)₂=P–P(^tBu)–P^tBu] ( 8 ) and [H₂C–P(^tBu)₂=P–P(P^tBu₂)–P(^tBu)] ( 9 ). Also 3 forms 8 with ^tBuPCl₂. The cleavage of the Me₃Si–P‐bond in 1 by means of C₂Cl₆ or N‐bromo‐succinimide yields (Cl)^tBuP–P=P(CH₃)^tBu₂ ( 10 ) or (Br)^tBuP–P=P(CH₃)^tBu₂ ( 11 ), resp. With LiP(SiMe₃)₂, 10 forms (Me₃Si)₂P–P(^tBu)–P=P(CH₃)^tBu₂ ( 12 ), and Et₂P–P(^tBu)–P=P(CH₃)^tBu₂ ( 13 ) with LiPEt₂. All compounds are characterized by ³¹P NMR Data and mass spectra; the ylide 5 and the THF adduct of 4 additionally by X‐ray structure analyses.     

Bildung und Eigenschaften von Li2P7R (R = Si(CH3)3, CH3, C(CH3)3)

Formation and Properties of Li₂P₇R (R = Si(CH₃)₃, CH₃, C(CH₃)₃) The reaction of P₇(Sime₃)₃ with Li₃P₇ in the molar ratio of 2:1 yields LiP₇(Sime₃)₂, and in the molar ratio of 1:2 Li₂P₇Sime₃ is formed. Li₂P₇me and Li₂P₇Cme₃ (me = CH₃) are obtained by reaction of white phosphorus with Lime, or LiCme₃, respectively [2]. The compounds Li₂P₇R (R = Sime₃, Cme₃, me) show typical valence tautomerism, as established by ³¹P-n.m.r. spectroscopy at various temperatures. Also LiP(Sime₃)₂ transforms P₇(Sime₃)₃ to yield Li₂P₇Sime₃ but in this reaction considerable cleavage of P? P bonds occurs, too.     

Kombination von Ionenaustausch und Gefriertrocknung als Syntheseweg zu neuen Oxoferraten(VI) M2FeO4 mit M = Li,Na, N(CH3)4, N(CH3)3Bzl,N(CH3)3Ph

Combination of Ion Exchange and Freeze Drying as a Synthetic Route to New Oxoferrates(VI) M₂FeO₄ with M = Li, Na, N(CH₃)₄, N(CH₃)₃Bzl, N(CH₃)₃Ph For the first time Oxoferrates(VI) M₂FeO₄ with M = Li, Na, N(CH₃)₄, N(CH₃)₃Bzl and N(CH₃)₃Ph have been prepared by cation exchange reaction on K₂FeO₄ and freeze drying of the resulting aqueous solutions. Li₂FeO₄ crystallizes as a monohydrate and decomposes at –10 ± 3 °C. Na₂FeO₄ crystallizes orthorhombically (Cmcm, a = 5.675(3) Å, b = 9.349(4) Å, c = 7.160(2) Å) and is isostructural to Na₂CrO₄. [N(CH₃)₄]₂FeO₄ crystallizes tetragonally (P4/nbm, a = 11.010(3) Å, c = 10.902(4) Å) and is isostructural to the room temperature modification of [N(CH₃)₄]₂SO₄. Infrared spectra of the alkylammonium ferrates(VI) show a decreasing influence of lattice forces on the vibrations of the FeO₄^2– ions with increasing cation size. Magnetic measurements show the expected paramagnetism for a d² ion.     

Determination of the isomerization rate constant HOCH2CH2CH2CH(OO·)CH3 →HOC·HCH2CH2CH(OOH)CH3. Importance of intramolecular hydroperoxy isomerization in tropospheric chemistry

The rate constant of the title reaction is determined during thermal decomposition of di-n-pentyl peroxide C₅H₁₁O( )OC₅H₁₁ in oxygen over the temperature range 463–523 K. The pyrolysis of di-n-pentyl peroxide in O₂/N₂ mixtures is studied at atmospheric pressure in passivated quartz vessels. The reaction products are sampled through a micro-probe, collected on a liquid-nitrogen trap and solubilized in liquid acetonitrile. Analysis of the main compound, peroxide C₅H₁₀O₃, was carried out by GC/MS, GC/MS/MS [electron impact EI and NH₃ chemical ionization CI conditions]. After micro-preparative GC separation of this peroxide, the structure of two cyclic isomers (3S*,6S*)3α-hydroxy-6-methyl-1,2-dioxane and (3R*,6S*)3α-hydroxy-6-methyl-1,2-dioxane was determined from ¹H NMR spectra. The hydroperoxy-pentanal OHC( )(CH₂)₂( )CH(OOH)( )CH₃ is formed in the gas phase and is in equilibrium with these two cyclic epimers, which are predominant in the liquid phase at room temperature. This peroxide is produced by successive reactions of the n-pentoxy radical: a first one generates the CH₃C·H(CH₂)₃OH radical which reacts with O₂ to form CH₃CH(OO·)(CH₂)₃OH; this hydroxyperoxy radical isomerizes and forms the hydroperoxy HOC·H(CH₂)₂CH(OOH)CH₃ radical. This last species leads to the pentanal-hydroperoxide (also called oxo-hydroperoxide, or carbonyl-hydroperoxide, or hydroperoxypentanal), by the reaction HOC·H(CH₂)₂CH(OOH)CH₃+O₂→O()CH(CH₂)₂CH(OOH)CH₃+HO₂. The isomerization rate constant HOCH₂CH₂CH₂CH(OO·)CH₃→HOC·HCH₂CH₂CH(OOH)CH₃ (k₃) has been determined by comparison to the competing well-known reaction RO₂+NO→RO+NO₂ (k₇). By adding small amounts of NO (0–1.6×10¹⁵ molecules cm⁻³) to the di-n-pentyl peroxide/O₂/N₂ mixtures, the pentanal-hydroperoxide concentration was decreased, due to the consumption of RO₂ radicals by reaction (7). The pentanal-hydroperoxide concentration was measured vs. NO concentration at ten temperatures (463–523 K). The isomerization rate constant involving the H atoms of the CH₂( )OH group was deduced: or per H atom: The comparison of this rate constant to thermokinetics estimations leads to the conclusion that the strain energy barrier of a seven-member ring transition state is low and near that of a six-member ring. Intramolecular hydroperoxy isomerization reactions produce carbonyl-hydroperoxides which (through atmospheric decomposition) increase concentration of radicals and consequently increase atmospheric pollution, especially tropospheric ozone, during summer anticyclonic periods. Therefore, hydrocarbons used in summer should contain only short chains (<C₄) hydrocarbons or totally branched hydrocarbons, for which isomerization reactions are unlikely. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 875–887, 1998     

Synthesis of (CH3C(CH2PPh2)3)CoL complexes (L = O2CO,S2CO,O2SO) through metal-assisted CO2, CS2, SO2 oxidation. Crystal structure of (CH3C(CH2PPh2)3)CO(O2SO)

The solution obtained by reduction of [(triphos)CO(μ-Cl)₂Co(triphos)]⁺² (triphos = CH₃C(CH₂PPh₂)₃) with Na/Hg reacts with CO₂, CS₂ and SO₂ to give (triphos)Co(O₂CO), (triphos)Co(S₂CO), and (triphos)Co(O₂SO), respectively. The molecular structure of the last has been established by X-ray difraction.     

Die Kristallstruktur von tert-Butylimidomethylindan, [CH3In?NC(CH3)3]4

The X-Ray Structure Determination of tert-Butylimido Methylindane, [CH₃In? NC(CH₃)₃]₄ The reaction of MeInCl₂ with LiN(H)^tBu in a 1 : 2 molar ratio forms [MeIn? N^tBu]₄ in high yield, lithium chloride, and the free amine H₂N^tBu. The crystal structure of the imidomethylindane with a cubic In₄N₄ skeleton has been determined.     

Polysulfonylamine. XXXVII. Darstellung von Quecksilberdimesylamiden. Kristall- und Molekülstrukturen von Hg[N(SO2CH3)2]2, Hg[{N(SO2CH3)2}2(DMSO)2] und Hg[{N(SO2CH3)2}2(HMPA)]

Polysulfonyl Amines. XXXVII. Preparation of Mercury Dimesylamides. Crystal and Molecular Structures of Hg[N(SO₂CH₃)₂]₂, Hg[{N(SO₂CH₃)₂}₂(DMSO)₂], and Hg[{N(SO₂CH₃)₂}₂(HMPA)] Hg[N(SO₂CH₃)₂]₂ ( 1 ) and Hg₂[N(SO₂CH₃)₂]₂ ( 2 a ) are formed as colourless, sparingly soluble precipitates when solutions of Hg(NO₃)₂ or Hg₂(NO₃)₂ in dilute nitric acid are added to an aqueous HN(SO₂CH₃)₂ solution. By a similar reaction, Hg₂[N(SO₂C₆H₄ ? Cl? 4)₂]₂ is obtained. 1 forms isolable complexes of composition Hg[N(SO₂CH₃)₂]₂ · 2 L with L = dimethyl sulfoxide (complex 3 a ), acetonitrile, dimethyl formamide, pyridine or 1,10-phenanthroline and a (1/1) complex Hg[N(SO₂CH₃)₂]₂ · HMPA ( 4 ) with hexamethyl phosphoramide. Attempted complexation of 2 a with some of these ligands induced formation of Hg⁰ and the corresponding Hg^II complexes. Crystallographic data (at -95°C) are for 1: space group 14₁/a, a = 990.7(2), c = 2897.7(8) pm, V = 2.844 nm³, Z = 8, D_x = 2.545Mgm^?3; for 4a: space group P1 , a = 767.8(2), b = 859.2(2), c = 925.2(2)pm α = 68.44(2), β = 86.68(2), γ = 76.24(2)°, V = 0.551nm³, Z = 1, D_x = 2.113 Mgm^?3; for 4: space group P2₁/c, a = 1041.3(3), b = 1545.4(3), c = 1542.5(3) pm, β = 100.30(2)°, V = 2.474nm³, Z = 4, D_x = 1.944Mgm³. The three compounds form molecular crystals. The molecular structures contain a linear or approximately linear, covalent NHgN moiety; the Hg? N distances and N? Hg? N angles are 206.7(4) pm and 176.3(2)° for 1, 207.2(2) pm and 180.0° for 3a, 205.7(4)/206.7(4) pm and 170.5(1)° for 4. In the complexes 3a and 4, the 0-ligands are bonded to the Hg atoms perpendicularly to the N? Hg? N axes, leading in 3a to a square-planar trans-(N₂O₂) coordination with Hg? 0 261.2(2) pm and N? Hg? O 92.3(1)/87.7(1)°, in 4 to a slightly distorted T-shaped (N₂O) geometry with Hg? 0 246.2(4)pm and N? Hg? 0 96.7(1)/92.0(1)°. In all three structures, the primary coordination is extended to a severely distorted (N₂O₄) hexacoordination by the appropriate number of secondary, inter- and/or intramolecular Hg…?0 inter-actions (0 atoms from sulfonyl groups, Hg…?O distances in the range 280—300pm). The intramolecular Hg…?O interactions give rise to nearly planar four-membered [HgNSO] rings. The molecule of 1 has a two-fold axis through the bisector of the N? Hg? N angle, the molecule of 3a an inversion center at the Hg atom. The molecule of 4 has no symmetry.     

A Tri-Coordinate-Magnesium Silylamide Complex: {[(CH3)3Si]2N}2MgO(CH2CH2)2OMg{N[Si(CH3)3]2}2

The reaction of diethylmagnesium dioxane adduct solution with 1,1,1,3,3,3-hexamethyldisilazan ((CH₃)₃SiNHSi(CH₃)₃) gives {[(CH₃)₃Si]₂N}₂MgO(CH₂CH₂)₂OMg{N[Si(CH₃)₃]₂}₂ (1); this alkoxomagnesium silylamide in the solid state contains unprecedented three-coordinate magnesium and oxygen atoms.     

The [Au(CH3SO3)4]– Anion in the Crystal Structures of M[Au(CH3SO3)4] (M = Li,Na, Rb)

The reactions of Au(OH)₃, M₂CO₃ (M = Li, Na, Rb), and methanesulfonic acid at elevated temperatures in sealed glass ampoules lead to single crystals of M[Au(CH₃SO₃)₄] (M = Li, Na, Rb). In the crystal structures of Li[Au(CH₃SO₃)₄] (tetragonal, I$\bar{4}$ , Z = 2,a = 938.64(2) pm, c = 917.01(3) pm, V = 807.93(4) ų) and Rb[Au(CH₃SO₃)₄] (tetragonal, P$\bar{4}$ 2₁c, Z = 2, a = 946.7(1) pm,c = 889.9(1) pm, V = 797.6(2) ų) the complex aurate anions are linked by the M⁺ ions in three dimensions. Contrastingly, in the structure of Na[Au(CH₃SO₃)₄] (triclinic, P$\bar{4}$ , Z = 1, a = 540.04(2) pm,b = 863.75(2) pm, c = 973.29(3) pm, α = 72.694(2)°, β = 75.605(2)°, γ = 77.687(2)°, V = 415.05(2) ų) the complex anions are connected into layers that are further connected by weak hydrogen bonds. The thermal decomposition of Li[Au(CH₃SO₃)₄] was monitored up to 500 °C and leads in a multi‐step process to elemental gold and Li₂SO₄.     

Darstellung von Dimethyl-N-Chlorammoniumtrifluormethansulfonat ((CH3)2NClH+ CF3SO3−)

Synthesis of Dimethyl-N-Chloroammonium Trifluoromethane Sulfonate ((CH₃)₂NClH⁺ CF₃SO₃^?) The weak base dimethyl-N-chloroamine, (CH₃)₂NCl, reacts with trifluormethane sulfonic acid at ?40 to ?30°C to give dimethyl-N-chloroammonium trifluoromethane sulfonate (CH₃)₂NClH⁺CF₃SO₃^?. The extremely hygroscopic salt decomposes upon melting at 107 to 108°C and thus is slightly more stable than the hydrogensulfate. Water or methanole liberate dimethyl-N-chloroamine from the salt. The salt is insoluble in ether and decomposes after dissolving in methylene chloride to give dimethylammonium trifluoromethane sulfonate (CH₃)₂NH₂⁺CF₃SO₃^?.     

S,N,N′-Substituted sulfurdiimines as ligands: II. Compounds [(ν3-RC3H4)Pd{R1NS(R2)NR1}] (R  H,CH3;R1  aryl; R2  CH3, t-C4H9) and some related triazenido and amidino compounds of palladium(II)

The complexes [(ν³-RC₃H₄)Pd{R¹NS(R²)NR¹}] (R  H, CH₃;R¹  aryl; R²  CH₃, t-C₄H₉) have been obtained from the reaction of [(ν³-RC₃H₄)PdCl]₂ with [Li{R¹NS(R²)NR¹}]; two isomers are produced, differing in the orientation of the allyl group. The sulfurdiimino group has some π-allylic character. The compounds decompose in solution into azo—arenes and [(ν³-RC₃H₄)Pd(SR²)]₂, and this is shown to be dependent upon steric and electronic factors.The properties of the sulfurdiimino compounds are compared with those of the compounds [(ν³-RC₃H₄)Pd(R³N₃R³)]₂ and [(ν³-RC₃H₄)Pd(R³NC(R⁴)NR³)]₂ (R  H, CH₃;R³  CH₃, aryl; R⁴  H, CH₃), which have been prepared by new methods.     

Organosilicon Amine Gels Based on 3-Aminopropyltriethoxysilane, Cobalt(II) or Chromium(III) Clorides, and Triethoxysilane

Organosilicon gels [Co(NH₂R²)₂Cl₂] and [Cr(NH₂R²)₃Cl₃], containing a diaminodichloride complex of cobalt(II) and triaminotrichloride complex of chromium(III) (R² = CH₂CH₂CH₂SiO(OEt)), were synthesized by the hydrolysis of complexes [Co(NH₂R¹)₂Cl₂] (I) and [Cr(NH₂R¹)₃Cl₃] (II) incorporating peripheral triethoxysilyl groups (R¹ = CH₂CH₂CH₂Si(OEt)₃). The coprecipitated [Co(NH₂R²)₂Cl₂] · 4NH₂R³, [Cr(NH₂R²)₃Cl₃] · 6NH₂R³, [Co(NH₂R²)₂Cl₂] · 2SiO₂, and [Cr(NH₂R²)₃Cl₃] ·xSiO₂ · (3 – x)SiHO_1.5 (R³ = CH₂CH₂CH₂SiO_1.5) gels were obtained by cohydrolysis of complexes I and II with 3-aminopropyltriethoxysilane or triethoxysilane. Interaction with SiH(OEt)₃ is accompanied by the decomposition of silicon hydride groups and the formation of tetraethoxysilane derivatives. The heating of dry gels in a flow of argon or oxygen to 600° results in the formation of amorphous silica having a specific surface area 2–467 m²/g and containing crystalline metals, their chlorides, oxides, silicates, or carbides.     

Vibrational spectra and normal co-ordinate analysis of CF3 compounds. Trimethyl(trifluoromethyl)silane,CF3Si(CH3)3 and CF3Si(CD3)3

The i.r. gas and Raman liquid spectra of CF₃Si(CH₃)₃ and CF₃Si(CD₃)₃ are reported and assigned for C_3vsymmetry. Force constants have been calculated by a combined analysis of both isotopomers yielding ƒ (SiCF₃) 2.63, ƒ (SiCH₃) 3.07 and ƒ (CF) 5.70 N cm⁻¹. The apparent weakness of the SiCF₃ bond confirms the results obtained on other CF₃ silanes and is discussed with respect to related molecules.