Sorption and transport of hydrocarbon and perfluorocarbon gases in poly(1‐trimethylsilyl‐1‐propyne)

Pure gas solubility and permeability of H₂, O₂, N₂, CO₂, CH₄, C₂H₆, C₃H₈, CF₄, C₂F₆, and C₃F₈ in poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) were determined as a function of pressure at 35°C. Permeability coefficients of the perfluorinated penetrants are approximately an order of magnitude lower than those of their hydrocarbon analogs, and lower even than those of the permanent gases. In striking contrast to hydrocarbon penetrants, PTMSP permeability to fluorocarbon penetrants decreases with increasing penetrant size. This unusual size‐sieving behavior in PTMSP is attributed to low perfluorocarbon solubilities in PTMSP coupled with low diffusion coefficients relative to those of their hydrocarbon analogs. In general, perfluorocarbon penetrants are less soluble than their hydrocarbon analogs in PTMSP. The difference in hydrocarbon and perfluorocarbon solubilities in high free volume, hydrocarbon‐rich PTMSP is much smaller than in hydrocarbon liquids and liquidlike polydimethylsiloxane. The low solubility of perfluorocarbon penetrants is ascribed to the large size of the fluorocarbons, which inhibits their dissolution into the densified regions of the polymer matrix and reduces the number of penetrant molecules that can be accommodated in Langmuir sites. From the permeability and sorption data, diffusion coefficients were calculated as a function of penetrant concentration. With the exception of H₂ and the C₃ analogs, all of the penetrants exhibit a maximum in their concentration‐dependent diffusion coefficients. Resolution of diffusion coefficients into a mobility factor and a thermodynamic factor reveals that it is the interplay between these two terms that causes the maxima. The mobility of the smaller penetrants (H₂, O₂, N₂, CH₄, and CO₂) decreases monotonically with increasing penetrant concentration, suggesting that the net free volume of the polymer–penetrant mixture decreases as additional penetrant is added to PTMSP. For larger penetrants mobility either: (1) remains constant at low concentrations and then decreases at higher penetrant concentrations (C₂H₆, CF₄, and C₂F₆); (2) remains constant for all concentrations examined (C₃H₈); or (3) increases monotonically with increasing penetrant concentration (C₃F₈). Presumably these results reflect the varying effects of these penetrants on the net free volume of the polymer–penetrant system. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 273–296, 2000     

Gas and vapor transport properties of amorphous perfluorinated copolymer membranes based on 2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole/tetrafluoroethylene

Teflon AF 2400 (Du Pont) is an amorphous, glassy perfluorinated copolymer containing 87 mol% 2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole and 13 mol% tetrafluoroethylene. The polymer has an extremely high fractional free volume of 0.327. Permeability coefficients for helium, hydrogen, carbon dioxide, oxygen, nitrogen, methane, ethane, propane, and chlorodifluoromethane (Freon 22) were determined at temperatures from 25 to 60°C and pressures from 20 to 120 psig. Permeation properties were also determined at a feed pressure of 200 psig at 25°C with a 2 mol% n-butane/98 mol% methane mixture. Permeabilities of permanent gases in Teflon AF 2400 are among the highest of all known polymers; the oxygen permeability coefficient at 25°C is 1600 × 10⁻¹⁰ cm³ (STP) cm/cm² s cmHg and the nitrogen permeability coefficient is 780 × 10⁻¹⁰ cm³ (STP) cm/cm² s cmHg. The permeabilities of organic vapors increase up to 20-fold as the vapor activity increases from 0.1 to unity, indicating that Teflon AF 2400 is easily plasticized. Although Teflon AF 2400 is an ultrahigh-free-volume polymer like poly(1-trimethylsilyl-1-propyne) [PTMSP], their gas permeation properties differ significantly. Teflon AF 2400 shows gas transport behavior similar to that of conventional, low-free-volume glassy polymers. PTMSP, on the other hand, acts more like a nanoporous carbon than a conventional glassy polymer.     

Vibrational Spectra of the Cyclic SN-Compounds S4N4, S4N4H4 and S3N3Cl3

The IR and Raman spectra of solid and dissolved S₄N₄, S₄N₄H₄, S₄N₄D₄ and S₃N₃Cl₃ have been recorded and are assigned according to D_2d, C_4v and C_3v symmetry respectively. In the solid state, many forbidden bands and splittings of degenerate vibrations are observed because of the symmetry lowering in the crystals. Due to the different size and shape of the rings and to strong coupling of the normal modes there is no clear correlation between the SN ring stretching vibrations and the strength of the SN bonds, except for the one of the E modes. However, the stretching force constant show the trend expected from changes in interatomic distances.     

The 1B1u ← 1A1g 0—0 transition in crystal benzene

The transition linewidth ΔE in crystal C₆H₆, C₆D₆ and sym-C₆H₃D₃ has been measured as a function of temperature T from 4.2 to 135°K, and it extrapolates to a common value of ΔE_o = 50 cm^? at O°K. In C₆H₆ ΔE = (50 + 7T^{$\text{1}\text{2}$}) cm^?1, indicative of strong exciton—phonon coupling, and there is a line shift of +40 cm^?1 per substituent deuteron. Fluorescence excitation spectral data are used to separate the ¹B_1u(= S₂) decay rate k_H = 9.4 × 10¹² sec^?1, derived from ΔE₀, into S₂S₁ internal conversion (rate ≈ 6.6 × 10¹² sec^?1) and S₂S_x (channel 3) internal conversion (rate ≈ 2.8 × 10¹² sec^?1. A similar value of k_H = 9.9 × 10¹² sec^?1 is obtained from the S₂S_o fluorescence quantum yield of liquid benzene.     

CH3SO3裂解反应的机理和热力学性质

在G3XMP2//B3LYP/6-311+G(3df,2p)水平上对CH₃SO₃裂解反应的机理进行了研究, 获得了6 条通道(10 条路径), 并构建了其势能剖面. 同时采用单分子反应理论计算了各个通道在温度200-3000 K区间的速率常数. 研究结果表明, 在计算温度范围内, CH₃SO₃裂解反应的主产物为P1(CH₃+SO₃), 产物P2(CH₃O+SO₂)和P3(HCHO+HOSO)仅在温度大于3000 K时对总产物有贡献, 而产物P4(CHSO₂+H₂O), P5(CH₂SO₃+H)和P6(CHSO₃+H₂)贡献相对较少. 将裂解反应总的速率常数拟合为k_total=1.40×10¹²T^0.15exp(7831.58/T). 此外, 根据统计热力学原理, 预测了所有物种的生成焓(D_fH^Θ_{298 K}, D_fH_{0 K}), 熵(S^Θ_{298 K})和热容(C_p, 298-2000 K), 计算的结果与实验值较接近.     

Freezing Point of Mixtures of C6H6 with C6D6 or 13C6H6 and of CH3COOH with CH3COOD or CD3COOD

The freezing points of mixtures of benzene, C₆H₆, with one of its isotopes, C₆D₆ and ¹³C₆H₆, and those of acetic acid CH₃COOH with its isotopes, CH₃COOD and CD₃COOD, were measured as functions of the molal concentrations of C₆D₆ and ¹³C₆H₆, CH₃COOD and CD₃COOD, respectively. They changed linearly or non-linearly with increasing molal concentration of C₆D₆ and ¹³C₆H₆, CH₃COOD, and CD₃COOD, respectively. These findings confirm Kiyosawas previous conclusion drawn from experiments on the freezing points of mixtures of H₂¹⁶O with H₂¹⁸O or H₂¹⁷O. This hypothesis states that even a difference in the number of neutrons in the hydrogen or oxygen atoms of water molecules makes water molecules behave as different entities with respect to the colligative properties of solutions. This concept can be extended to mixtures of ordinary benzene with either of its isotopes, C₆D₆ or ¹³C₆H₆, and those of ordinary acetic acid CH₃COOH with either of its isotopes, CH₃COOD or CD₃COOD.     

Enantiomeric products formed via different mechanisms: asymmetric hydrogenation of an α,β-unsaturated carboxylic acid involving a Ru(CH3COO)2[(R)-binap] catalyst

Hydrogenation of (Z)-3-phenyl-2-butenoic acid with a Ru(CH₃COO)₂[(R)-binap] (BINAP=2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) catalyst in methanol gives (S)-3-phenyl-2-butanoic acid and its R enantiomer in a 97:3 (4 atm) to 94:6 (100 atm) ratio in quantitative yield. Both hydrogen gas and protic methanol participate in the saturation of the olefinic bond. Analysis of the products obtained using (Z)-3-phenyl-2-butenoic acid-3-¹³C and either H₂, a 1:1 H₂-D₂ mixture, or D₂ in CH₃OD indicates that several catalytic cycles are operative, showing different reactivity and stereoselectivity. The major S enantiomer was formed primarily by the standard Ru monohydride mechanism, whereas the minor R isomer is produced via more complicated routes.     

Etude vibrationnelle des composes (C4H4P)Mn(CO)3 et [C4H2(CH3)2P]Mn(CO)3 et calcul du champ de force du cycle C4H4P complexe

The Raman and infrared spectra (4000200 cm^?1) of (C₄H₄P)Mn(CO)₃ and (C₄D₄P)Mn(CO)₃, and of [C₄H₂(CH₃)₂P]Mn(CO)₃ and [C₄D₂(CH₃)₂P]Mn(CO)₃ in the liquid and solid states (10–400 K) have been investigated. A complete vibrational assignment is proposed and valence force fields of the (C₅H₅) and (C₄H₄P) cycles are compared. From these results, it is clearly shown that the (C₄H₄P) rings are more electrophilic and weaker π-electron donors than (C₅H₅) rings, this is in agreement with their chemical behavior.     

Role of B(C6F5)3 in activating the nickel-methyl complex (η-C5H5)Ni(CH3)(PPh3) to initiate the vinyl polymerization of norbornene

The Ni-methyl complex (η⁵-C₅H₅)Ni(CH₃)(PPh₃) (1) reacted with B(C₆F₅)₃ to give an unstable contact ion-pair complex with a μ-methyl bridge between the Ni and B atoms. Formation of the B-CH₃ bond was confirmed by the reaction of this complex with PPh₃ to give [(η⁵-C₅H₅)Ni(PPh₃)₂][B(CH₃)(C₆F₅)₃] which was structurally characterized. Spontaneous decomposition of the contact ion-pair complex yielded (η⁵-C₅H₅)Ni(C₆F₅)(PPh₃) which is very stable and does not show any reactions with norbornene with or without added B(C₆F₅)₃. ¹⁹F NMR study showed that the polynorbornene obtained by the catalysis of 1/B(C₆F₅)₃ system has the C₆F₅ end-group. A series of reactions, which includes CH₃/C₆F₅ exchange between the Ni and B centers with concomitant dissociation of PPh₃ to accept coordination of a norbornene monomer, is proposed as the route to active species that can initiate vinyl polymerization of norbornene.     

The enthalpies of formation of CH3Mn(CO)5 and of CH3Re(CO)5, and the strengths of the CH3Mn and CH3Re bonds

From measurements of the heats of iodination of CH₃Mn(CO)₅ and CH₃Re(CO)₅ at elevated temperatures using the ‘drop’ microcalorimeter method, values were determined for the standard enthalpies of formation at 25° of the crystalline compounds: ΔH^o_f[CH₃Mn(CO)₅, c] = ?189.0 ± 2 kcal mol^?1 (?790.8 ± 8 kJ mol^?1), ΔH^o_f[Ch₃Re(CO)₅,c] = ?198.0 ± kcal mol^?1 (?828.4 ± 8 kJ mo^?1). In conjunction with available enthalpies of sublimation, and with literature values for the dissociation energies of MnMn and ReRe bonds in Mn₂(CO)₁₀ and Re₂(CO)₁₀, values are derived for the dissociation energies: D(CH₃Mn(CO)₅) = 27.9 ± 2.3 or 30.9 ± 2.3 kcal mol^?1 and D(CH₃Re(CO)₅) = 53.2 ± 2.5 kcal mol^?1. In general, irrespective of the value accepted for D(MM) in M₂(CO)₁₀, the present results require that, D(CH₃Mn) = $\text{1}\text{2}$D(MnMn) + 18.5 kcal mol^?1 and D(CH₃Re) = $\text{1}\text{2}$D(ReRe) + 30.8 kcal mol^?1.     

Iodomethane oxidative addition and CO migratory insertion in monocarbonylphosphine complexes of the type [Rh((C6H5)COCHCO((CH2)nCH3))(CO)(PPh3)]: Steric and electronic effects

The chemical kinetics, studied by UV/Vis, IR and NMR, of the oxidative addition of iodomethane to [Rh((C₆H₅)COCHCOR)(CO)(PPh₃)], with R = (CH₂)_nCH₃, n = 1-3, consists of three consecutive reaction steps that involves isomers of two distinctly different classes of Rh^III-alkyl and two distinctly different classes of Rh^III-acyl species. Kinetic studies on the first oxidative addition step of [Rh((C₆H₅)COCHCOR)(CO)(PPh₃)] + CH₃I to form [Rh((C₆H₅)COCHCOR)(CH₃)(CO)(PPh₃)(I)] revealed a second order oxidative addition rate constant approximately 500-600 times faster than that observed for the Monsanto catalyst [Rh(CO)₂I₂]⁻. The reaction rate of the first oxidative addition step in chloroform was not influenced by the increasing alkyl chain length of the R group on the β-diketonato ligand: k₁ = 0.0333 ([Rh((C₆H₅)COCHCO(CH₂CH₃))(CO)(PPh₃)]), 0.0437 ([Rh((C₆H₅)COCHCO(CH₂CH₂CH₃))(CO)(PPh₃)]) and 0.0354 dm³ mol⁻¹ s⁻¹ ([Rh((C₆H₅)COCHCO(CH₂CH₂CH₂CH₃))(CO)(PPh₃)]). The pK_a^′ and keto-enol equilibrium constant, K_c, of the β-diketones (C₆H₅)COCH₂COR, along with apparent group electronegativities, χ_R of the R group of the β-diketones (C₆H₅)COCH₂COR, give a measurement of the electron donating character of the coordinating β-diketonato ligand: (R, pK_a^′, K_c, χ_R) = (CH₃, 8.70, 12.1, 2.34), (CH₂CH₃, 9.33, 8.2, 2.31), (CH₂CH₂CH₃, 9.23, 11.5, 2.41) and (CH₂CH₂CH₂CH₃, 9.33, 11.6, 2.22).     

Permeation and sorption in polynorbornenes with organosilicon substituents

Gas sorption properties, permeability coefficients, and diffusion coefficients of a series of norbornene polymers are presented. Introduction of the Si(CH₃)₃ group into the polynorbornene (PNB) backbone chain results in significant increases in glass transition temperature, permeability, and diffusion coefficient for a number of gases (H₂, O₂, N₂, CO₂, CH₄, C₂H₆). The transport properties and sorption isotherms for poly(5-trimethylsilyl norbornene) (PTMSNB) are very similar to those for poly(vinyltrimethyl silane) (PVTMS), which contains the same side-chain group but differs from PTMSNB by the structure of its main chain. For another silicon-containing polymer poly[5-(1,1,3,3-tetramethyl-1,3-disilabutyl) norbornene] (PDSNB) having a bulkier side-chain group, the glass-transition temperature is decreased in comparison with that of PNB, presumably owing to self-plasticization. Both silicon-containing norbornene polymers (PTMSNB and PDSNB) have permeability coefficients for “rapid” gases like H₂ or CO₂ of about 10² Barrer. The high values of the Langmuir sorption capacity C′_H for PTMSNB and PVTMS, as well as the high diffusivity and mobility of spin probes in these polymers, were attributed to a large free volume related to the bulky Si(CH₃)₃ groups attached directly to the main chain. © 1993 John Wiley & Sons, Inc.     

Structure-permeability relationships in silicone polymers

Permeability coefficients P for He, O₂, N₂, CO₂ CH₄, C₂H₄, C₂H₆, and C₃H₈ in 12 different silicone polymer membranes were determined at 35.0°C and pressures up to 9 atm. Values of P for CO₂, CH₄, and C₃H₈ were also determined at 10.0 and 55.0°C. In addition, mean diffusion coefficients D and solubility coefficients S were obtained for CO₂, CH₄, and C₃H₈ in 6 silicone polymers at 10.0, 35.0, and 55.0°C. Substitution of increasingly bulkier functional groups in the side and backbone chains of silicone polymers results in a significant decrease in P for a given penetrant gas. This is due mainly to a decrease in D , whereas S decreases to a much lesser extent. Backbone substitutions appear to have a somewhat lesser effect in depressing P than equivalent side-chain substitutions. The selectivity of a silicone membrane for a gas A relative to a gas B, i.e., the permeability ratio P (A)/P (B), may increase or decrease as a result of such substitutions, but only if the substituted groups are sufficiently bulky. The selectivity of the more highly permeable silicone membranes is controlled by the ratio S (A)/S (B), whereas the selectivity of the less permeable membranes depends on both the ratios D (A)/D (B) and S(A)/S(B). The permeability as well as the selectivity of one silicone membrane toward CO₂ were significantly enhanced by the substitution of a fluorine-containing side group that increased the solubility of CO₂ in that polymer.     

Energy analysis of metal-metal bonding in [RM-MR] (M = Zn, Cd, Hg; R = CH3, SiH3, GeH3, C5H5, C5Me5)

The metal-metal bonds of the title compounds have been investigated with the help of energy decomposition analysis at the DFT/TZ2P level. In good agreement with experiment, computations yield Hg-Hg bond distance in [H₃SiHg-HgSiH₃] of 2.706 Å and Zn-Zn bond distance in [(η⁵-C₅Me₅)Zn-Zn(η⁵-C₅Me₅)] of 2.281 Å. The Cd-Cd bond distances are longer than the Hg-Hg bond distances. Bond dissociation energies (-BDE) for Zn-Zn bonds in zincocene −70.6 kcal/mol in [(η⁵-C₅H₅)₂Zn₂] and −70.3 kcal/mol in [(η⁵-C₅Me₅)₂Zn₂] are greater amongst the compounds under study. In addition, [(η⁵-C₅H₅)₂M₂] is found to have a binding energy slightly larger than those in [(η⁵-C₅Me₅)₂M₂]. The trend of the M-M bond dissociation energy for the substituents R shows for metals the order GeH₃ < SiH₃ < CH₃ < C₅Me₅ < C₅H₅. Electrostatic forces between the metals are always attractive and they are strong (−75.8 to −110.5 kcal/mol). The results demonstrate clearly that the atomic partial charges cannot be taken as a measure of the electrostatic interactions between the atoms. The orbital interaction (covalent bonding) ΔE_orb is always smaller than the electrostatic attraction ΔE_elstat. The M-M bonding in [RM-M-R] (R = CH₃, SiH₃, GeH₃, C₅H₅, C₅Me₅; M = Zn, Cd, Hg) has more than half ionic character (56-64%). The values of Pauli repulsions, ΔE_Pauli, electrostatic interactions, ΔE_elstat, and orbital interactions, ΔE_elstat are larger for mercury compounds as compared to zinc and cadmium.     

XPS STUDIES ON SURFACE MODIFIED POLY [1-(TRIMETHYLSILYL)-1-PROPYNE] MEMBRANES Ⅱ SURFACE MODIFICATION BY BROMINE VAPOR*

Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH_3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C_(1s) spectra and some newbands, e. g. at 1220 and 580cm~(-1) in IR spectra were formed. The fact,t Po_2, permeability ofoxygen, decreased and α_(O_2/N_2), separation factor of oxygen relative to nitrogen, increased withbromination time, shows that surface modification of PTMSP by bromine may be an efficient approach to prepare PTMSP membranes used for practical gas separations.     

Rotational and vibrational distributions of N2(C 3Πu) excited by state-selected Ar(3P2) and Ar(3P0) metastable atoms

The ESR method is used to study the oxidation kinetics of the CH₃, C₂H₅, n-C₄H₉, i-C₄H₉, s-C₄H₉, t-C₄H₉, n-C₆H₁₃, C₆H₁₁, C₆H₅CH₂, CH₃C₆H₄CH₂, and C₆H₅CH₂CH₂ radicals in methanol matrix at 87 K. The reaction kinetics are shown to be describable in terms of a time-dependent rate constant k(t). The contribution from the matrix relaxation to k(t) has been determined. The oxidation rate and the shape of the kinetic curve are independent of the type of the radical. Models interpreting the experimental data are discussed.     

Synthesis and properties of pentamethylmetallocene derivatives Cp*MCp (M = Ru, Fe). Crystal structure of the salt [CpRuC5Me4CH2+OC6H2(NO2)3-]

Photolysis of a solution of Cp*RuCp (1) in CF₃CO₂H generates salt [CpRu(C₅Me₄CH₂)]-(O₂CCF₃)(2 • O₂CCF₃). The reaction of compound 1 with oleum at 20 °C through the intermediate dication [η⁵-(CH₂C₅Me₄)Ru(μ:η⁵,ν⁵-C₅H₄C₅H₅)Ru(C₅Me₄CH₂)-η⁶]²⁺ leads to the triply charged cation η⁷CH₂)₂C₅Me₃Ru(μη⁵,η⁵-C₅H₄C₅H₄)Ru(C₅Me₄CH₂)-η⁶]³⁺. Synthesis of pentamethylmetallocene derivatives CpMC₅Me₄X (M = Ru, Fe; X = CHO, CH₂OH, CH₂An) has been accomplished. The reactions of 1-hydroxymethyl-2,3,4,5-tetramethylruthenocene with acids CF₃CO₂H, HBF₄, CF₃CO₂H/NaB[C₆H₃(CF₃)₂]₄, and picric acid C₆H₂(NO₂)₃OH afforded salts 2•X (X = CF₃CO₂, BF₄, B[C₆H₃(CF₃)₂]₄), and (2,3,4,5-tetram ethylruthenocenyl)methyl picrate [CpRu(C₅Me₄CH₂)-η⁶][(C₆H₂(NO₂)₃O] (2•C₆H₂(NO₂)₃O). Structure of the latter was characterized by single crystal X-ray diffraction.     

Kinetic studies of the reactions of the carbene complex W(CO)5[C(SCH3)2] with phosphines to form phosphorane complexes W(CO)5[(CH3S)2C-PR3] and the synthesis of some cyclic phosphorane complexes

The dithiocarbene complex W(CO)₅[C(SCH₃)₂ reacts with tertiary phosphines, PPh₂CH₃, PPh(CH₃)₂, P(C₂H₅)₃ and P(OCH₃)₃ to form the phosphorane complexes W(CO)₅[CH₃S)₂C-PR₃] and with HPPh₂ to form the phosphine complex W(CO)₅[PPh₂[CH(SCH₃)₂]. Kinetic studies of both types of reactions show that their rates are first order each in W(CO)₅[C(SCH₃)₂] and in the phosphorus ligand. A mechanism involving rate determining phosphorus attack at the carbene carbon followed by rapid rearrangement to the product is consistent with this rate law. Rate constants for the reactions increase with increasing nucleophilicities of the phosphines: P(OCH₃)₃ < PPh₂H < PPh₂C_H3 ? PPh(CH₃)₂ < P(C₂H₅)₃. The ΔH values decrease (P(OCH₃)₃ > PPh₂H > PPh₂(CH₃) > PPh(CH₃)₂ > P(C₂H₅)₃) as the nucleophilicities of the phosphines increase. The ΔS values (≈-30 e.u.) remain essentially constant for all the reactions. The cyclic dithiorcarbenes W(CO)₅[CS(CH₂)_nS], wheren- 3 or 4, react with PPh₂(CH₃) to form the cyclic phosphorane complexes, W(CO)₅[S(CH₂)_nSC-PPh₂(CH₃)]. The 6- and 7- membered cyclic dithiocarbenes also react with PPh₂H to form the phosphine complexes, W(CO)₅ {PPh₂- [CS(CH₂)_nS(H)]}.     

Reaction of some tertiary phosphines and phosphites with [Co(η5-C5H5)(S2C2{CN}2)]

Reaction of the 16 electron monomer [Co(η⁵-C₅H₅)(S₂C₂{CN}₂)] with various tertiary phosphines and phosphites (L) gives readily the 18 electron monomers [Co(η⁵-C₅H₅)(S₂C₂{CN}₂)L] which for L = P(OR)₃ have J($\text{P}$C₅$\text{H}$₅) ca. 6 Hz but J($\text{P}$C₅$\text{H}$₅) = 0 for L = PR₃.     

Reactions of (η5-C5H5)2Tir compounds with organic cyanides

The syntheses and properties of the titanium(III) complexes Cp₂Tir · R′CN (R = C₆H₅, o-, m-, p-CH₃C₆H₄, CH₂C₆H₅, C₆F₅, Cl; R′ = CH₃, t-C₄H₉, C₆H₅, o-CH₃C₆H₄, 2,6-(CH₃)₂C₆H₃) are described. In the complexes the nitrogen atom of the cyanide ligands is coordinated to the metal. The thermal stabilities of the complexes depend markedly on R and R′; on heating they undergo a novel reaction in which two cyanide ligands are coupled by formation of a CC bond, while the metal is oxidized to titanium(IV).