Acetonitrile Complex Research Articles

Ruthenium Aqua Complexes Supported by the Kläui Tripodal Ligand: Synthesis, Structure, and Application in Catalytic C–H Oxidation in Water

Water‐soluble ruthenium(III) aqua complexes supported by the Kläui tripodal ligand [Co(η5‐C5H5){P(O)(OEt)2}3]– (LOEt–) have been synthesized and structurally characterized, and their use as catalysts for C–H oxidation in water has been studied. The treatment of [Ru(LOEt)Cl2(MeCN)] with N‐donor ligands afforded the adducts [Ru(LOEt)Cl2(L)] (L = tBuNH2 (1), pyridine (2), imidazole (3)). Refluxing [Ru(LOEt)Cl2(MeCN)] in neat tBuNH2 gave the amidine complex [Ru(LOEt)Cl2{N(H)C(Me)NHtBu}] (4). Chloride abstraction of 1–3 with AgOTs (OTs = tosylate) in 1 M p‐toluenesulfonic acid afforded the water‐soluble RuIII diaqua complexes [Ru(LOEt)(H2O)2(L)](OTs)2 (L= tBuNH2 (5), pyridine (6), imidazole (7)), whereas that for 4 yielded the triaqua complex [Ru(LOEt)(H2O)3](OTs)2 (8). The crystal structures of 4, 5, 7, and 8 have been determined. The reduction of 5 with Zn dust in D2O gave a diamagnetic RuII species, whereas that in MeCN led to isolation of the RuII acetonitrile complex [RuII(LOEt)(MeCN)2(tBuNH2)](PF6) (9), which has been characterized by X‐ray diffraction. The RuIII aqua complexes proved to be moderately efficient catalysts for C–H bond oxidation with tert‐butyl hydroperoxide in water. For example, the oxidation of ethylbenzene with tert‐butyl hydroperoxide in water at room temperature in the presence of 0.1 mol‐% of 8 afforded acetophenone in ca. 62 % yield.

Thermodynamic investigations of complexation between dibenzo 18-crown-6 with Ni2+, Zn2+ and Cd2+ cations in pure acetonitrile, pure dimethylesulfoxide and acetonitrile-dimethylesulfoxide binary mixtures using conductometric method

The stability constants of 1:1 (M-L) complexes of Dibenzo-18-crown-6 (DB18C6) with Ni2+, Zn2+ and Cd2+ cations have been determined conductometrically. The conductance data show that the stoichiometry of the complexes formed between the macrocyclic ligand and Ni2+, Zn2+ and Cd2+ cations is 1:1 (M:L). GENPLOT computer program used to find the stability constants of the complexes were obtained from fitting of molar conductivity curves. The selectivity order of DB18C6 for the metal cations changes with the nature and composition of the binary mixed solvent. We also determined the Gibbs standard free energies (∆G0), the standard enthalpy changes (∆H0) and standard entropy changes (∆S0) for formation of these complexes in acetonitrile – dimethylesulfoxide (AN-DMSO) binary mixtures for the complexation. The values of standard enthalpy changes (∆H0 ) for complexation reactions were obtained from the slope of the van’t Hoff plots and the changes in standard entropy (∆S0) were calculated from the relationship ∆G0298.15 = ∆H0 - 298.15 ∆S0.

Synthesis, Spectral, and Coordination Properties of Halogen-Substituted Tetraarylporphyrins

2,3,7,8,12,13,17,18-Ocatbromo-5,10,15,20-tetra-(4-chloroprienyl)porphyrin and 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra-(4-bromophenyl)porphyrin have been synthesized. The obtained compounds have been identified by electronic absorption and 1H NMR spectroscopy as well as mass spectrometry. The complex-forming properties of the synthesized porphyrins in the zinc acetate (II)-acetonitrile system at 278–298 K have been studied. Kinetic parameters of the formation of the corresponding zinc complexes in acetonitrile have been determined.

Synthesis, Characterization, and Reactivity of an Ethynyl Benziodoxolone (EBX)-Acetonitrile Complex.

The synthesis of a crystalline ethynyl-1,2-benziodoxol-3(1 H)-one (EBX)-acetonitrile complex is described. EBX has been widely used as an active species for a variety of reactions; however, its high instability has so far prevented its isolation. The EBX-acetonitrile is self-assembled into a double-layered honeycomb structure through weak hypervalent iodine secondary interactions and hydrogen bonding. The N-ethynylation of a variety of sulfonamides using the EBX-acetonitrile complex as a substrate under mild conditions is also described.

Electrochemical and Photochemical Reduction of CO2 Catalyzed by Re(I) Complexes Carrying Local Proton Sources

The novel rhenium complexes fac-Re(pdbpy)(CO)3Cl (pdbpy = 4-phenyl-6-(phenyl-2,6-diol)-2,2′-bipyridine), 1, and fac-Re(ptbpy)(CO)3Cl (ptbpy = 4-phenyl-6-(phenyl-3,4,5-triol)-2,2′-bipyridine), 2, have been synthesized, and the single crystal X-ray diffraction (SC-XRD) structure of 1 was solved. The electrochemical behaviors of the complexes in acetonitrile under Ar and their catalytic performances for CO2 reduction with added water and MeOH are discussed. A detailed IR spectroelectrochemical study under Ar and CO2 atmospheres coupled with DFT calculations allows the identification of reduced species and the interpretation of the reduction mechanisms. Comparison between the rhenium complexes and the corresponding Mn derivatives Mn(pdbpy)(CO)3Br, 3, and Mn(ptbpy)(CO)3Br, 4, has been also considered. Finally, photostimulated conversion of the CO2 was investigated with catalysts (1, 3, and 4) under visible light irradiation (λ > 420 nm) in acetonitrile as solvent. Remarkably, 1 and 3 catalysts were active towa...

A Mononuclear Nonheme Iron(IV)-Oxo Complex of a Substituted N4Py Ligand: Effect of Ligand Field on Oxygen Atom Transfer and C-H Bond Cleavage Reactivity.

A mononuclear iron(II) complex [FeII(N4PyMe2)(OTf)](OTf)(1), supported by a new pentadentate ligand, bis(6-methylpyridin-2-yl)- N, N-bis((pyridin-2-yl)methyl)methanamine (N4PyMe2), has been isolated and characterized. Introduction of methyl groups in the 6-position of two pyridine rings makes the N4PyMe2 a weaker field ligand compared to the parent N4Py ligand. Complex 1 is high-spin in the solid state and converts to [FeII(N4PyMe2)(CH3CN)](OTf)2 (1a) in acetonitrile solution. The iron(II) complex in acetonitrile displays temperature-dependent spin-crossover behavior over a wide range of temperature. In its reaction with m-CPBA or oxone in acetonitrile at -10 °C, the iron(II) complex converts to an iron(IV)-oxo species, [FeIV(O)(N4PyMe2)]2+ (2). Complex 2 exhibits the Mössbauer parameters δ = 0.05 mm/s and Δ EQ = 0.62 mm/s, typical of N-ligated S = 1 iron(IV)-oxo species. The iron(IV)-oxo complex has a half-life of only 14 min at 25 °C and is reactive toward oxygen-atom-transfer and hydrogen-atom-transfer (HAT) reactions. Compared to the parent complex [FeIV(O)(N4Py)]2+, 2 is more reactive in oxidizing thioanisole and oxygenates the C-H bonds of aliphatic substrates including that of cyclohexane. The enhanced reactivity of 2 toward cyclohexane results from the involvement of the S = 2 transition state in the HAT pathway and a lower triplet-quintet splitting compared to [FeIV(O)(N4Py)]2+, as supported by DFT calculations. The second-order rate constants for HAT by 2 is well correlated with the C-H bond dissociation energies of aliphatic substrates. Surprisingly, the slope of this correlation is different from that of [FeIV(O)(N4Py)]2+, and 2 is more reactive only in the case of strong C-H bonds (>86 kcal/mol), but less reactive in the case of weaker C-H bonds. Using oxone as the oxidant, the iron(II) complex displays catalytic oxidations of substrates with low activity but with good selectivity.

Ethylene and Cyclohexene Oxidation by p-Benzoquinone, Hydrogen Peroxide, and Oxygen in the Solutions of Cationic Pd(II) Complexes in Acetonitrile–Water and Ionic Liquid–Water Binary Solvents

Optimal conditions are selected for ethylene and cyclohexene oxidation reactions in the acetonitrile (AN)–water system in the presence of $${\text{Pd}}{{({\text{AN}})}_{x}}({{{\text{H}}}_{2}}{\text{O}})_{{4 - x}}^{{2 + }}$$ complexes. It is shown that hydrogen peroxide oxidizes hydroquinone (QН2) in acetonitrile solutions and in ionic liquids ( $${\text{BMI}}{{{\text{M}}}^{ + }}{\text{BF}}_{4}^{ - },$$ $${\text{BMI}}{{{\text{M}}}^{ + }}{\text{PF}}_{6}^{ - }$$ ), and the rates of ethylene oxidation in the $${\text{BMI}}{{{\text{M}}}^{ + }}{\text{PF}}_{6}^{ - }$$ ionic liquid in the presence of p-benzoquinone (Q) and hydroquinone are the same. It is shown that solid and soluble phthalocyanine iron complexes catalyze oxidation of olefins by oxygen in acidic acetonitrile media by converting p-benzoquinone to the third catalyst of the process. The apparent first-order rate constants of hydroquinone oxidation by oxygen are determined. The use of the IL–Н2О–Н2SO4 system is found to be inappropriate for cyclohexanone synthesis because of the formation of byproducts of cyclohexene conversion.

Facile synthesis of 1,5-disubstituted tetrazoles by reacting a ruthenium acetylide complex with trimethylsilyl azide.

Treatment of [Ru]-C[triple bond, length as m-dash]CPh (1, [Ru] = (η5-C5H5)(dppe)Ru, dppe = Ph2PCH2CH2PPh2) with trimethylsilyl azide afforded the cationic nitrile complex {[Ru]NCCH2Ph}[N3] (2) and the further cycloaddition of 2 with trimethylsilyl azide at 60 °C afforded the N(2)-bound tetrazolato complex [Ru]N4CCH2Ph (3). The regiospecific alkylation of 3 gave a series of cationic N(2)-bound N(4)-alkylated-5-benzyl tetrazolato complexes {[Ru]N4(CH2R)CCH2Ph}[Br] (4a, R = C6F5; 4b, R = Ph; 4c, R = 4-CN-C6H4; 4d, R = 2,6-F2-C6H3; 4e, R = 6-CH2Br-C5NH3) and the subsequent cleavage of the Ru-N bond of 4a-4e gave N(1)-alkylated-5-benzyl tetrazoles N4(CH2R)CCH2Ph (5a-5e) in good to excellent yields and [Ru]-Br, which, on reacting with phenylacetylene, resulted in the formation of 1 thus forming a reaction cycle. The structures of 2, 3, 4a, 4c and 5a were confirmed by single-crystal X-ray diffraction analysis.

Spectroscopic and electronic structure characterization of hydrogen bonding in 2-Bromohydroquinone

2-Bromohydroquinone species form both intra- and inter-molecular H-bonds. The evidences for the H-bonds have been observed in the solid-phase Mid IR (4000−400 cm−1) and Near IR (8000−5000 cm−1) absorption spectra with two intensely broad bands near 3263 and 3222 cm−1 and a broad absorption in 7000−5200 cm−1 with a band maximum at 6335 cm−1. Dimer and trimer models with DFT's B3LYP and BP86 functionals using 6-31G(d) and 6-311++G(d,p) basis sets have been proposed for the OH⋯O bonding in 2-Bromohydroquinone. Out of the four predicted conformers, one trans and one cis conformers with nearly 1:1 Boltzmann populations, are separated by very small energy difference of 0.03 kcal/mol and this is confirmed by two chemical shifts at 9.0 and 9.3 ppm from an 1H NMR spectrum. On the basis of Quantum Theory of Atoms in Molecules (AIM) and reduced density gradient plots of electron densities and its isosurfaces by non-covalent interactions (NCI) method, the influence of the OH⋯Br, weak van der Waals and OH⋯O bond interactions on the stability of dimer and trimer structures have been analysed. From the natural bond orbital (NBO) analysis, it is explained that the formation of H-bonding may be attributed to charge transfer from the lone pair orbital n(O) of the base Oxygen into the vacant antibonding orbital σ*(OH) of the acid OH in the OH⋯O bonding. The Near IR concentration-dependent spectra demonstrate that the sample of 2-Bromohydroquinone is composed of OH⋯O bonded species and dissociate into non-bonded species as the mole fraction of the solvent (acetonitrile/1,4-dioxane) is increased. The band observed at 7095 cm−1 at 0.09 M is identified as the first overtone of the OH stretching mode of the weak complex of 2-Bromohydroquinone and acetonitrile. The solvent effects on all the observed solution-phase NIR spectra are not ruled out.

Chemical and Electrochemical Properties of [Cp*Rh] Complexes Supported by a Hybrid Phosphine-Imine Ligand

A series of [Cp*Rh] complexes (Cp* = η5-pentamethylcyclopentadienyl) bearing the κ2-[P,N]-8-(diphenylphosphino)quinoline (PQN) ligand have been prepared and characterized. Chemical or electrochemical reduction of the rhodium(III) form generates an isolable rhodium(I) complex; this rhodium(I) complex reacts with a range of organic acids to yield a rhodium(III) hydride bearing [Cp*] in the η5 mode and [PQN] in the expected κ2 mode. Solid-state structures of these three compounds from X-ray diffraction studies reveal only small changes in the intraligand bond distances across the series, suggesting the redox events associated with interconversion of these compounds are primarily metal centered. Cyclic voltammetry data show that the rhodium(III) chloride complex undergoes a two-electron reduction at −1.19 V vs ferrocenium/ferrocene, whereas the analogous solvento rhodium(III) acetonitrile complex undergoes two sequential one-electron reductions. The rhodium(III) hydride undergoes an irreversible, ligand-centered reduction near −1.75 V vs ferrocenium/ferrocene. Carrying out this reduction alone or in the presence of added of triethylammonium as a source of protons results in only modest yields of H2, as shown by bulk electrolyses and chemical reduction experiments. These results are discussed in the context of recent work with [Cp*Rh] complexes bearing more symmetric 2,2′-bipyridyl and diphosphine ligands.

Applications of Rozen’s Reagent in Oxygen-Transfer and C–H Activation Reactions

Rozen’s reagent (hypofluorous acid–acetonitrile complex, HOF·MeCN) is a robust nonspecific oxygen-transfer reagent and became a proven tool for the oxidation of difficult-to-oxidize molecules. It has been applied to instant oxygen transfers to functional groups such as alkenes, alkynes, and aromatic hydrocarbons, epoxidation, oxidation of alcohols, amines, and alkynes, oxygen-transfer reactions with nitrogen, phosphorus, and sulfur-containing substrates, and α-hydroxylation of carbonyl groups. Apart from being a potential green oxidizing agent, the complex has applications in 18O-labeling and C–H functionalization strategies. Recent uses of Rozen’s reagent in developing nanomaterials and oxidized expanded graphite indicate the enormous potential of the reagent. These aspects are discussed in this review.1 Introduction2 Synthesis and Physical Properties3 Safety and Handling4 Oxygen-Transfer Reactions4.1 General Mechanism of Oxygen Transfer4.2 Epoxidation4.3 Oxidation of Alkynes4.4 Oxidation of Aromatic Alcohols and Phenols4.5 Oxidation of Nitrogen-Containing Compounds4.6 Conversion of Aldehydes into Nitriles4.7 Oxidation of Alcohols and Ethers4.8 Oxidation of Sulfur-Containing Compounds4.9 Oxygen-Transfer Reaction with Phosphine, Phosphite, and Phosphinite Compounds5 C–H Activation Reactions5.1 Hydroxylation of Nonactivated Tertiary Saturated Carbon Center5.2 Hydroxylation of Aromatic Carbon Center5.3 α-Hydroxylation of Carbonyl Group5.4 Activation of α-Hydrogens of α-Amino Acids6 Other Uses7 Green Chemistry and Rozen’s Reagent8 Experimental Problems9 Further Applications10 Conclusions

A bi-nuclear Cu(II)-complex for selective epoxidation of alkenes: Crystal structure, thermal, photoluminescence and cyclic voltammetry

Herein, we report the molecular and supramolecular structure, photoluminescence, redox behavior and product selective catalytic activity of [Cu2(oxalate)(1,10-phen)2Cl2] (where 1,10-phen = 1,10-phenanthroline) synthesized by using hydrophilic oxalate as bridging ligand and the hydrophobic 1,10-phen as the blocker ligand. Structural analysis reveals that this binuclear Cu(II)-complex crystallizes in achiral monoclinic P21/n space group and it has a 3D supramolecular structure. Each Cu-center displays five coordinated distorted square pyramidal geometry. Two such Cu centers are connected by oxalato-bridge to form the bi-nuclear-metal core and two 1,10-phen molecules block the outer periphery of the core and restrains further polymerization. These binuclear metallic units are connected by supramolecular hydrogen bonding and π⋯π interactions to form a 3D supramolecular architecture. The complex is stable up to 230 °C. A reversible redox couple centered at (E1/2) ∼ −27 mV with ΔEp ∼ 206 mV corresponding to the CuII/I couple was detected in the cyclic voltammogram of the complex in acetonitrile. The complex shows emission maxima at 451 and 480 nm upon excitation at 340 nm due to π-π* transition in the aromatic π-rings of 1,10-phenanthroline. Density functional analysis has been performed to explore the molecular structure and character of the orbitals within the complex. Due to the presence of five coordinated Cu-centers, the lewis acidic catalytic activity of the complex has been studied. It exhibits selective oxidation behavior for alkenes in presence of several oxidants. It shows 100% selectivity with 70% conversion for the oxidation of cis-cyclooctene to corresponding epoxide at 50 °C in presence of H2O2 as oxidant in acetonitrile.

NITRILE COMPLEXES AS EFFECTIVE ANTIMICROBIAL ADDITIVES

Antimicrobial properties of nitrile complexes of transition metal salts were studied including the investigation of their activity in surfactants and mineral oil environments. Experiments of the polymeric complexes preparation by in-situ copolymerization of the nitrile polymers in the presence of transition metal salts and reactions of transition metal salts added to the ready polymers were performed. The dependence of the polymer complexes forming particularities on central metal atoms nature was determined.

Designed To React: Terminal Copper Nitrenes and Their Application in Catalytic C-H Aminations.

Heteroscorpionate ligands of the bis(pyrazolyl)methane family have been applied in the stabilisation of terminal copper tosyl nitrenes. These species are highly active intermediates in the copper-catalysed direct C-H amination and nitrene transfer. Novel perfluoroalkyl-pyrazolyl- and pyridinyl-containing ligands were synthesized to coordinate to a reactive copper nitrene centre. Four distinct copper tosyl nitrenes were prepared at low temperatures by the reaction with SO2 tBuPhINTs and copper(I) acetonitrile complexes. Their stoichiometric reactivity has been elucidated regarding the imination of phosphines and the aziridination of styrenes. The formation and thermal decay of the copper nitrenes were investigated by UV/Vis spectroscopy of the highly coloured species. Additionally, the compounds were studied by cryo-UHR-ESI mass spectrometry and DFT calculations. In addition, a mild catalytic procedure has been developed where the copper nitrene precursors enable the C-H amination of cyclohexane and toluene and the aziridination of styrenes.

Synthesis and characterization of three hetero-dinuclear complexes with CuO2M cores (M = Na, Hg): Exploration of their phenoxazinone synthase mimicking activity

Three new hetero-dinuclear complexes, [CuL1Na(NCS)]·0.5H2O (1), [CuL1Na(OClO3)]·0.25H2O (2) and [CuL2HgCl2] (3) {where H2L1 = N,N′-bis(3-ethoxysalicylidene)-2,2-dimethylpropane-1,3-diamine and H2L2 = N,N′-bis(3-methoxysalicylidene)-2,2-dimethylpropane-1,3-diamine] are N2O4 donor compartmental Schiff bases} have been synthesized and characterized. The phenoxazinone synthase mimicking activity of each complex in acetonitrile has been investigated with the model substrate o-aminophenol.

The electronic spectra and the structures of the individual copper(II) chloride and bromide complexes in acetonitrile according to steady-state absorption spectroscopy and DFT/TD-DFT calculations

The results of spectrophotometric study and quantum chemical calculations for copper(II) chloro- and bromocomplexes in acetonitrile are reported. Electronic spectra of the individual copper(II) halide complexes were obtained in a wide spectral range 200–2200 nm. Stability constants of the individual copper(II) halide complexes in acetonitrile were calculated: log β1 = 8.5, log β2 = 15.6, log β3 = 22.5, log β4 = 25.7 for [CuCln]2−n and log β1 = 17.0, log β2 = 24.6, log β3 = 28.1, log β4 = 30.4 for [CuBrn]2−n. Structures of the studied complexes were optimized and electronic spectra were simulated using DFT and TD-DFT methodologies, respectively. According to the calculations, the more is the number of halide ligands the less is coordination number of copper ion.

Uranyl tris nitrato as a luminescent probe for trace water detection in acetonitrile.

Uranyl tris nitrato i.e. [UO2 (NO3 )3 ]- was formed by adding tetramethylammonium nitrate to uranyl nitrate in acetonitrile medium. The luminescence features of this complex in acetonitrile are very sensitive to water content, which could lead to the use of it as a luminescent probe for water present in acetonitrile. The luminescence intensity ratio of 507 to 467nm peak of uranyl tris nitrato showed a linear response in the range 0-5% (v/v) water content in acetonitrile. The present method was applied for three synthetic samples of acetonitrile for water detection and the results obtained were compared using Karl Fischer titration. There was a good agreement in the values obtained by both the methods.

Electrochemical properties and C-H bond oxidation activity of [Ru(tpy)(pyalk)Cl]+ and [Ru(tpy)(pyalk)(OH)

[Ru(tpy)(pyalk)Cl]Cl (pyalk = 2-(2'-pyridyl)-2-propanol) was synthesized and characterized crystallographically and electrochemically. Upon dissolution in water and acetonitrile, [Ru(tpy)(pyalk)Cl]Cl was found to form [Ru(tpy)(pyalk)Cl]+ and [Ru(tpy)(pyalk)(OH)]+, respectively. The Ru(ii/iii) couple of [Ru(tpy)(pyalk)Cl]+ was found to be relatively low compared to that of other Ru complexes in acetonitrile, but the Ru(iii/iv) couple was not significantly different than other Ru complexes bearing anionic ligands. Pourbaix diagrams were generated for [Ru(tpy)(phpy)(OH2)]+ (phpy = 2-phenylpyridine) and [Ru(tpy)(pyalk)(OH)]+ in water, and it was found that [Ru(tpy)(pyalk)(OH)]+ has a lower Ru(ii/iii) potential than [Ru(tpy)(phpy)(OH2)]+ under neutral to alkaline pH. [Ru(tpy)(pyalk)(OH)]+ was found to catalyze C-H bond hydroxylation of secondary alkanes and epoxidation of alkenes using cerium(iv) ammonium nitrate as the primary oxidant.

Conformation-dependent phosphorescence emission of individual mononuclear ruthenium-(ii)-bis-terpyridine complexes.

The potential of supramolecular transition metal coordination complexes to form robust, long-living, radiative charge transfer states makes this class of triplet state emitters ideal candidates for application as photosensitizes or in photonic devices. Antenna-enhanced phosphorescence experiments on single Ru2+-bis-terpyridine complexes incorporated into a thin PMMA film show that phosphorescence emission spectra can exhibit shifts depending on the local environment [J. F. Herrmann, P. S. Popp, A. Winter, U. S. Schubert and C. Höppener, ACS Photonics, 2016, 3, 1897-1906]. Here, we demonstrate that the environmentally altered spectral properties of individual dual-luminescent Ru2+-bis-terpyridine complexes in PMMA and acetonitrile can be reproduced by DFT-based vibrationally resolved Franck-Condon spectra, if the phosphorescent emission of different molecular conformations is taken into account. Furthermore, we demonstrate that the triplet emission of these complexes occurs from a metal-to-ligand charge transfer (MLCT) state.

On the interactions of nitriles and fluoro-substituted pyridines with silicon tetrafluoride: Computations and thin film IR spectroscopy

The nature of the interactions between silicon tetrafluoride and series of nitrogen bases, including nitriles (RCN, with R > CH3), pyridine, and various fluoro-substituted pyridines, has been investigated via quantum-chemical computations, low-temperature IR spectroscopy, and bulk reactivity experiments. Using (primarily) M06 with the 6-311+G(2df,2pd) basis set, we obtained equilibrium structures, binding energies, harmonic frequencies, and N–Si potentials in the gas-phase and in bulk dielectric media for an extensive series of 1:1 molecular complexes, including: C6H5CH2CN–SiF4, CH3CH2CN–SiF4, (CH3)3CCN–SiF4, C5H5N–SiF4, 4-FC5H4N–SiF4, 3,5-C5F2H3N–SiF4, 2,6-C5F2H3N–SiF4 and 3,4,5-C5F3H2N–SiF4. In addition, for the analogous 2:1 complexes of pyridine and 3,5-difluororpyridine, we obtained equilibrium structures, binding energies, and harmonic frequencies. The N–Si distances in the 1:1 nitrile complexes are fairly long, ranging from 2.84 Å to 2.88 Å, and the binding energies range from 4.0 to 4.2 kcal/mol (16.7–17.6 kJ/mol). Also, computations predict extremely anharmonic N–Si potentials, for which the inner portions of the curve are preferentially stabilized in dielectric media, which predict an enhancement of these interactions in condensed-phases. However, we see no evidence of bulk reactivity between C6H5CH2CN, CH3CH2CN, or (CH3)3CCN and SiF4, nor any significant interaction between (CH3)3CCN and SiF4 in low temperature IR spectra of solid, (CH3)3CCN/SiF4 thin films. Conversely, the interactions in four of the five 1:1, pyridine-SiF4 complexes are generally stronger; binding energies range from 5.7 to 9.6 kcal/mol (23.8–40.2 kJ/mol), and correspondingly the N–Si distances are relatively short (2.12–2.25 Å). The exception is 2,6-C5F2H3N–SiF4, for which the binding energy is only 3.6 kcal/mol (15.1 kJ/mol), and the N–Si distance is quite long (3.12 Å). In addition, both pyridine and 3,5-difluororpyridine were found to form stable reaction products with SiF4; but no analogous product was obtained with 2,6-difluororpyridine and SiF4, nor was any significant interaction indicated in low-temperature IR spectra of 2,6-difluororpyridine/SiF4 films. By contrast, low temperature spectra of pyridine/SiF4 and 3,5-difluororpyridine/SiF4 thin films are consistent with the presence of a distinct 2:1 reaction product. Moreover, the observed frequencies agree reasonably well with those predicted for the cis, octahedral coordination isomers of the 2:1 molecular complexes, in which the N–Si bonds are compressed slightly relative to those in the predicted gas-phase structures.