Dicarbonyls of Carbon and Methylidyne Cations - The Journal of

Subscriber access provided by University of Newcastle, Australia

Article

Dicarbonyls of Carbon and Methylidyne Cations Jiaye Jin, Lili Zhao, Xiaonan Wu, Wei Li, Yuhong Liu, Diego M. Andrada, Mingfei Zhou, and Gernot Frenking J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.7b00739 • Publication Date (Web): 27 Mar 2017 Downloaded from http://pubs.acs.org on March 29, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

The Journal of Physical Chemistry A is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

Dicarbonyls of Carbon and Methylidyne Cations

Jiaye Jin,a# Lili Zhao,b# Xiaonan Wu,a Wei Li,a Yuhong Liu,a Diego M. Andrada,b Mingfei Zhou,a* Gernot Frenkingb* a

Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and

Innovative Materials, Collaborative Innovation Center of Chemistry for Energy Materials,

Fudan

University,

Shanghai

200433(China).

E-mail:

[email protected]. b

Fachbereich

Chemie,

Philipps-Universität

Marburg,

Hans-Meerwein-Strasse,

D-35043 Marburg, Germany. Email: [email protected]. #

Contributed equally to this work.

Abstract. The carbon suboxide cation C3O2+ and the protonated carbon suboxide HC3O2+/DC3O2+ were produced in the gas phase. The vibrational spectra were measured via infrared photodissociation spectroscopy of their argon- or CO-tagged complexes. Spectroscopic evidence combined with state-of-the-art quantum chemical calculations indicate that both cations have a bent C2v symmetry and can be designated as dicarbonyls of carbon cation and methylidyne cation, respectively.

1

ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60



INTRODUCTION The carbodiphosphorane C(PPh3)2 firstly synthesized in 1961, is usually

classified as diylide whose bonding situation was described with the notation R3P=C=PR.1 Based on its electronic structure and chemical behavior, the molecule was recently suggested by one of us to be best described as a donor-acceptor complex of a carbon atom in the excited 1D state and two phosphane ligands.2 This led to the introduction of carbones as compounds of divalent zero oxidation state carbon with two lone pairs of electrons at carbon.3 Systematic theoretical studies showed that the donor-acceptor bonding model can be extended to the other main group elements including nitrogen, boron and heavier group 14 elements.4-7 Based on this bonding strategy, a large number of main group mono- and multinuclear zero or low oxidation state complexes have been synthesized employing different ligands.8-32 The development of the concept of carbones also led to the rethinking of the bonding in some other previously known main-group compounds.33-35 Carbon suboxide, a stable oxide of carbon with a chemical formula C3O2 that was already synthesized in 190636 is a well-known reactant in synthetic chemistry.37 It’s bonding is conventionally described as a linear cumulene O=C=C=C=O. However, high-resolution infrared spectroscopic investigations indicated that the molecule in the gas phase is bent with an angle of 156° at the central carbon atom.38 This is in excellent agreement with high-level ab initio calculations at the CCSD(T)/cc-pVQZ level, which predicted a bond angle of 155.9° with a very flat bending potential.39 The deviation from linearity and the very shallow bending potential of carbon suboxide are difficult to explain with the standard bonding model of a cumulene while it becomes plausible when the donor–acceptor model is employed.35,36 The ground-state C3O2 molecule is classified as a dicarbonyl complex of carbon in its 1D excited state

2


Page 2 of 28

Page 3 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


with two lone pairs of electrons.4 Thus, it acts as a strong Lewis base, which was determined to have a quite large proton affinity.40,41 Both the carbon suboxide cation C3O2+ and the protonated carbon suboxide HC3O2+ have been prepared in the gas phase and their reactivity was studied by mass spectrometric methods.41,42 Two isomers of protonated carbon suboxide HC3O2+ were generated from various precursors. The vibrational frequency of HC3O2+ was calculated at a rather low level of theory (HF/6-31G**) by present standard.

41

Here we report a combined experimental and theoretical study of the carbon suboxide cation C3O2+ and the protonated carbon suboxide HC3O2+ and its deuterated isotopomer DC3O2+ in the gas phase. Their experimental infrared spectra are reported for the first time and the nature of the bonding situation is analyzed with modern methods of quantum chemistry. Infrared spectroscopic in conjunction with state-of-the-art quantum chemical calculations confirm that the cations can be designated as dicarbonyls of carbon cation and methylidyne cation, respectively, demonstrating that the donor-acceptor bonding model may be extended to the hydrocarbon ions. The ionic species are potentially important molecules in space as the C+, CH, CH+ and CO fragments are among the most important building blocks of interstellar organic molecules.43,44 The C3O2 neutral has been proposed to be important carbon-containing material in the coma dust and the nucleus.45



EXPERIMENTAL AND COMPUTATIONAL METHODS The experiments were performed using a collinear tandem time-of-flight mass

spectrometer equipped with a laser vaporization supersonic expansion cluster ion source that was described in detail previously.46 Briefly, the cation complexes were

3



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

produced by laser ablation (532nm; Spectral Physics GCR-150) of a graphite target. The ions were entrained by a He carrier gas seeded with either 5% CO or 2%CO/10% Ar or 5% CO/0.1%CH4 (CD4) and underwent a supersonic expansion to form a collimated and cold molecular beam. The composition of the cation complexes was controlled by the vaporization laser power, carrier gas stagnation pressures and the time delay between the carrier gas pulse and the ablation laser. The cations were extracted and mass separated by a time-of-flight mass spectrometer. The species of interest were mass-selected and decelerated before being subjected to infrared photodissociation by a tunable IR laser generated via an OPO/OPA system (Laser Vision) pumped by an Nd: YAG laser (Continuum Surelite EX). When the IR laser is on resonance with a vibrational fundamental of the ion complex, absorption takes place, which results in dissociation of the complex. The fragment ions together with the undissociated parent ions were reaccelerated and detected by a second collinear time-of-flight mass spectrometer. IR spectra were recorded by monitoring the relative yield of fragment ions as a function of the photodissociation IR laser wavelength. The spectra were recorded by scanning the dissociation laser in steps of 2 cm-1 and averaging over 300 laser shots at each wavenumber. The geometries of the molecules have been optimized using coupled-cluster theory47 at the CCSD(T)/cc-pVTZ48 level of theory. Analytical Hessians were computed to determinate the nature of the stationary points and to calculate the harmonic frequencies. All calculations were carried out using MOLPRO 2012.49 For the bonding analysis we calculated the molecules using the gradient corrected functional BP8650,51 in conjunction with uncontracted Slater-type orbitals (STOs) as basis functions.52 The latter basis sets for all elements have triple-ζ quality augmented by two sets of polarization functions (ADF-basis set TZ2P+). This level of theory is

4


Page 4 of 28

Page 5 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


denoted BP86/TZ2P+. An auxiliary set of s, p, d, f, and g STOs was used to fit the molecular densities and to represent the Coulomb and exchange potentials accurately in each SCF cycle.53 The BP86/TZ2P+ calculations were performed using the CCSD(T)/cc-pVTZ

optimized

geometries

with

the

program

package

ADF2013.01.54,55

The interatomic interactions were investigated by means of an energy decomposition analysis (EDA, also termed extended transition state method - ETS) developed independently by Morokuma56 and by Ziegler and Rauk.57 The bonding analysis focuses on the instantaneous interaction energy ΔEint of a bond A–B between two fragments A and B in the particular electronic reference state and in the frozen geometry of AB. This interaction energy is divided into three main components [Eq. (1)]. ΔEint = ΔEelstat + ΔEPauli + ΔEorb

(1)

The term ΔEelstat corresponds to the quasiclassical electrostatic interaction between the unperturbed charge distributions of the prepared atoms and is usually attractive. The Pauli repulsion ΔEPauli is the energy change associated with the transformation from the superposition of the unperturbed electron densities  A   B ˆ [   ] , which properly of the isolated fragments to the wavefunction  0  N  A B

ˆ operator) and obeys the Pauli principle through explicit antisymmetrization (  renormalization (N = constant) of the product wavefunction. ΔEPauli comprises the destabilizing interactions between electrons of the same spin on either fragment. The orbital interaction ΔEorb accounts for charge transfer and polarization effects. The ΔEorb term can be decomposed into contributions from each irreducible representation of the point group of the interacting system. Further details on the EDA/ETS method58

5



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 28

and its application to the analysis of the chemical bond59-62 can be found in the literature. The EDA-NOCV63 method combines charge (NOCV) and energy (EDA) decomposition schemes to decompose the deformation density which is associated with the bond formation, Δρ, into different components of the chemical bond. The EDA-NOCV calculations provide pairwise energy contributions for each pair of interacting orbitals to the total bond energy. NOCV (Natural Orbital for Chemical Valence)64,65 is defined as the eigenvector of the valence operator,

, given by

Equation (2): (2) In the EDA-NOCV scheme the orbital interaction term, ΔEorb, is given by Equation (3):

(3) In which

and

are diagonal transition state Kohn-Sham matrix

elements corresponding to NOCVs with the eigenvalues -vk and vk, respectively. The term of a particular type of bond are assigned by visual inspection of the shape of the deformation density, Δρk, which is given by equation 4:

(4)

 RESULTS AND DISCUSSION The C3O2+ and HC3O2+ ions were produced in a laser vaporization supersonic

6


Page 7 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


molecular beam ion source and investigated using infrared photodissociation spectroscopy. The mass peak corresponds to C3O2+ (m/z=68) and is one of the most intense peak in the mass spectrum using a graphite target in expansion of helium gas seeded with 5% CO (Figure S1(a) of Supporting Information). The mass spectrum from the experiment using 13C substituted CO sample (Figure S1(b)) indicates that the observed C3O2+ species originates from the reaction of one carbon from graphite and two CO molecules in the ion source. The energy of IR photons near the CO stretching frequency region is not sufficient to cause efficient dissociation of the strongly bound C3O2+ cation. The rare gas “tagging” technique is employed to enhance the dissociation yield.66-69 The argon-tagged [C3O2·Ar]+ complex was produced and selected, which can fragment by eliminating argon after photo excitation of the C3O2+ core ion vibrations. The spectrum shown in Figure 1 consists of two well-resolved bands centered at 2096 and 2168 cm-1, which can be assigned to the antisymmetric and symmetric CO stretching vibrations of the C3O2+ core ion. The observation of two CO stretching modes implies that the C3O2+ cation is bent. A weak broad band above 2200 cm-1 is also observed, which can be attributed to overtone or combination modes. Relatively strong combination bands above the CO stretching vibrational fundamental were observed in the infrared spectrum of the C3O2 neutral as well.38 Earlier photoelectron spectroscopic study reported a symmetric CO stretching vibration of 2105  40 cm-1 for C3O2+.70 Figure 1 The carbon suboxide cation reacts readily with methane to form the protonated HC3O2+ cation when traces of methane (0.1%) are doped into the carrier gas (see mass spectra in Figure S2 of Supporting Information). Since the HC3O2+ cation cannot dissociate with an infrared laser, the HC4O3+ cation is formed and selected for

7



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 28

photodissociation (Figure S3 of Supporting Information). The HC4O3+ cation dissociates very efficiently by losing a carbon monoxide fragment with unfocused laser beam, indicating that this CO ligand is very weakly bonded. Therefore, the HC4O3+ cation can be regarded as a “CO-tagged” complex [HC3O2·CO]+. The CO-tagging is expected to have very little effect on the structure and spectrum of the HC3O2+ core ions. We note that the HC4O3+ ion (m/z=97) has equal mass with HC8+ and the

13

C12C3O3+ isotopomer of C(CO)3+ with natural isotopic abundance. The

involvement of these ions to the infrared spectrum of [HC3O2·CO]+ can be ruled out as the HC8+ cation cannot dissociate via the loss of CO and the

C C3O3+ cation

13 12

cannot dissociate with unfocused IR laser beam. The infrared photodissociation spectrum of [HC3O2·CO]+ is shown in Figure 2(a). The spectrum consists of three bands at 3044, 2292 and 2208 cm-1, which can be attributed to the C-H stretching, symmetric and antisymmetric CO stretching vibrations of the HC3O2+ core ion. The tagged CO stretching mode is expected to be weak and is likely overlapped by the strong 2208 cm-1 band. Three bands at 2306, 2262 and 2200 cm-1 are observed in the spectrum of [DC3O2·CO]+, as shown in Figure 2(b). The assignments of the three modes were made by comparison with the calculated frequencies (see theoretical part below). The strongest 2200 cm-1 band, which is just 8 cm-1 red-shifted from the antisymmetric stretching mode of HC3O2+ can be related to the antisymmetric CO stretching mode of the DC3O2+ core ion. The C-D stretching mode and the symmetric CO stretching mode are coupled. The 2262 cm-1 band, which is red-shifted by 30 cm-1 from the symmetric CO stretching mode of HC3O2+, is assigned to the symmetric CO stretching mode of DC3O2+. The 2306 cm-1 band is attributed to the C-D stretching mode. The vibrational fundamentals of free CH+ and CD+ were determined via electronic spectroscopy to be 2739.7 and 2035.4 cm-1 in the gas phase,71,72 much

8


Page 9 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


lower than the corresponding modes observed here for HC3O2+ and DC3O2+. Figure 2 Quantum chemical calculations have been carried out to investigate the geometries, bond dissociation energies and vibrational frequencies of the molecules. Figure 3 shows the optimized geometries and bond dissociation energies (BDEs) at the CCSD(T)/cc-pVTZ level of the parent cation C3O2+, the argon complex [C3O2·Ar]+, the protonated and deuterated species HC3O2+ and DC3O2+ as well as the CO tagged adducts [HC3O2·CO]+ and [DC3O2·CO]+. The unpaired electron in C3O2+ is in the π orbital, which means that the cation has a 2B1 electronic ground state. The calculated bending angle of C3O2+ (134.8o) is more acute than in neutral C3O2 (156o).38 The computed geometry of C3O2 at the CCSD(T)/cc-pVTZ level gives a bending angle of 154.7o and a C-CO bond length of 1.285 Å,39 which is much shorter than in C3O2+ (1.342 Å). But the bond strength of the CO ligands with C+ is higher than with neutral C. The BDE for dissociation of the CO ligands in C3O2+ (De = 152.1 kcal/mol) surpasses the value for C3O2 (De = 136.0 kcal/mol).73 This is yet another example for the finding that bond length and bond strength do not necessarily correlate.74,75 Figure 3 Calculations indicate that argon can only be tagged to the central carbon atom of C3O2+. Figure 3b shows that the attachment of the argon atom has only a minor influence on the geometry, which agrees with the very small bond dissociation energy (BDE) of Ar (De = 2.0 kcal/mol). The argon atom is not in the molecular plane of the C3O2+ moiety, the argon-tagged complex [C3O2·Ar]+ has Cs symmetry and a 2A' electronic state. Larger changes of the bond angle and bond lengths are observed for the C3O2+ moiety in HC3O2+ and DC3O2+, which have essentially the same geometry

9



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(Fig. 3c, d). The C-C-C angle becomes more acute (119.5o) while the C-C bonds become longer (1.367 Å) and the C-O bonds slightly shorter (1.133 Å) than in free C3O2+. The BDE of hydrogen atom (De = 120.8 kcal/mol) which is the same as for deuterium is much higher than for Ar. The carbonyl ligands in HC3O2+ and DC3O2+ are more strongly bonded than in C3O2+, although the C-C distances in the former species are longer. The BDE for dissociation of two CO ligands in HC3O2+ and DC3O2+ (De = 176.5 kcal/mol) is larger than in C3O2+ (De = 152.1 kcal/mol). The optimized geometries of [HC3O2·CO]+ and [DC3O2·CO]+ suggest that the weakly bonded tagged CO group is trans to the C-H (De = 6.1 kcal/mol) and C-D bonds (De = 6.1 kcal/mol; Fig. 3e, f). We located a second equilibrium structure for each species with C2v symmetry where the CO ligand is bonded with the carbon atom to hydrogen or deuterium, respectively (Figure S4 of Supporting Information). The latter isomers are 0.64 kcal/mol higher in energy than the species that are shown in Figure 3e, f). Table 1 Table 1 shows the most important experimental and calculated vibrational frequencies of the [C3O2·Ar]+, [HC3O2·CO]+ and [DC3O2·CO]+ cations. The calculated values of the harmonic frequencies are uniformly higher than the experimental values, which is well known.76 There is in good agreement between the calculated and experimental shifts of the symmetric and asymmetric C-O stretching modes in [HC3O2·CO]+ and [DC3O2·CO]+ relative to [C3O2·Ar]+. The calculated values are particularly helpful for the assignment of the C-D stretching mode in [DC3O2·CO]+, which has a very similar value as the symmetric C-O frequency. The calculations suggest that the highest lying mode comes from the C-D vibration. Besides the C2v structure of HC3O2+, another isomer OCCCOH+ was also detected by mass spectrometry techniques.41 The OCCCOH+ isomer is predicted to be

10


Page 10 of 28

Page 11 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


25.3 kcal/mol less stable than the C2v isomer at the B3LYP/aug-cc-pVTZ level. As shown in Figure S5 of Supporting Information, the less stable OCCCOH isomer can clearly be ruled out. In previous report, a third isomer with the proton added to one of the two equivalent carbon atoms were also considered.41 We found that this structure is not a local minimum and geometry optimization converges to the most stable structure at the B3LYP/aug-cc-pVTZ level. Table 2 We analyzed the nature of the two carbonyl bonds in C3O2+ and HC3O2+ with the EDA-NOCV method in order to obtain insight into the bonding situation, which shall be compared them with the dative bonds in carbon suboxide OC→C←CO.35,36,73 Table 2 shows the numerical results of the calculations where the fragments (2P) C+ + (CO)2 were used for C3O2+ and (1Δ) CH+ + (CO)2 for HC3O2+. Note that the singlet reference state of CH+ is the excited 1Δ state, which has two electrons in the π orbital that give rise to OC←CH+→CO π backdonation. It becomes obvious that the orbital interactions come mainly from the σ donation of the carbonyl ligands to the positively charged acceptor moieties. The contribution of the π backdonation is much weaker than in C3O2, which has a neutral carbon atom as central moiety.73 Figure 4 A useful feature of the EDA-NOCV method is the possibility to graphically display the change in the electronic structure that is associated with the pairwise orbital interaction.77-79 Figures 4a-c show the three most important pairs of occupied/vacant MOs of CH+ and (CO)2 and the connected deformation densities Δρ. The color code of the charge flow is red→blue. The strongest orbital interaction ΔE1 comes from the σ donation OC→CH+←CO of the in-phase (+,+) combination of the lone-pairs of CO, which is the HOMO-1 of (CO)2, into the LUMO of (1Δ) CH+. The

11



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

EDA analysis of neutral C3O273 was carried out with the electron configuration 2s02p2 2p||0 2p2 of the carbon atom, which makes the out-of-phase (+,-) σ donation stronger than the in-phase (+,+) σ donation. The σ donation OC→CH+←CO from the HOMO of (CO)2, which is the out-of-phase (+,-) combination of the carbonyl electron lone-pairs into the LUMO+1 of (1Δ) CH+, gives rise to the second strongest orbital interaction ΔE2. The π backdonation OC←CH+→CO ΔE3 is much weaker than the σ donation, because the donor fragment is a cation. Figure 4d shows the deformation densities Δρ of the three most important orbital interactions between (2P) C+ and (CO)2 in the cation C3O2+, which look very similar as Δρ1-3 of HC3O2+. Note that the shape of Δρ1 for C3O2+ and for HC3O2+ has an area of charge concentration (red) in the middle of the central carbon atom. This signals a local charge accumulation at the carbon atom that arises from the hybridization caused by the binding interactions with the CO ligands. The initial 2P state of the carbon atom in the EDA-NOCV calculation of C3O2+ has the electron configuration 2s22p0 2p||0 2p1. It changes toward a sp hybridization of the 2s and 2p AOs.



CONCLUSIONS The carbon suboxide cation C3O2+ and the protonated carbon suboxide HC3O2+

and its deuterated isotopomer DC3O2+ have been prepared in the gas phase via a laser vaporization supersonic cluster ion source. The vibrational spectra are measured via mass-selected infrared photodissociation spectroscopy of their argon- or CO-tagged complexes. Spectroscopic combined with state-of-the-art quantum chemical calculations indicate that the carbon suboxide cation C3O2+ has a 2B1 electronic ground state with a bent C2v structure, and the pronated carbon suboxide cation HC3O2+ has a 1A1 ground state with a more acute CCC bending angle than that of

12


Page 12 of 28

Page 13 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


carbon suboxide cation. Bonding analysis indicates that the C3O2+ and HC3O2+cations can be designated as dicarbonyls of carbon cation in the 2P ground state and methylidyne cation in the excited

1

Δ state, respectively. The analysis of the

donor-acceptor interactions between C+/CH+ and CO with the EDA-NOCV method indicates that the orbital interactions come mainly from the σ donation of the carbonyl ligands to the positively charged acceptor moieties. The contribution of the π backdonation is much weaker than in C3O2, which has a neutral carbon atom as central moiety.



ACKNOWLEDGMENTS The work at Fudan was financially supported by the National Natural Science

Foundation of China (grant nos 21688102, 21573047 and 21433005). The work at Marburg was supported by the Deutsche Forschungsgemeinschaft. LZ thanks the Alexander von Humboldt Foundation for a postdoctoral fellowship.

Supporting Information The mass spectra, calculated geometries, bond dissociation energies and vibrational frequencies, and complete ref 49. This material is available free of charge via the Internet at http://pubs.acs.org.

13



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60



Page 14 of 28

REFERENCES

(1) Ramirez, F.; Hansen, B.; Desai, N. B.; McKelvie, N. Hexaphenyl Carbodiphosphorane, (C6H5)3PCP(C6H5)3. J. Am. Chem. Soc. 1961, 83, 35393540. (2) Tonner,

R.;

Oexler,

F.;

Neumuller,

B.;

Petz,

W.;

Frenking,

G.

Carbodiphosphoranes: The Chemistry of Divalent Carbon(0). Angew. Chem. Int. Ed. 2006, 45, 8038-8042. (3) Frenking, G.; Tonner, R. Divalent Carbon(0) Compounds. Pure Appl. Chem. 2009, 81, 597-614. (4) Celik, M. A.; Sure, R.; Klein, S.; Kinjo, R.; Bertrand, G.; Frenking, G. Borylene Complexes (BH)L2 and Nitrogen Cation Complexes (N+)L2: Isoelectronic Homologues of Carbones CL2. Chem. Eur. J. 2012, 18, 5676-5692. (5) Takagi, N.; Shimizu, T.; Frenking, G. Divalent Silicon(0) Compounds. Chem. Eur. J. 2009, 15, 3448-3456. (6) Takagi, N.; Shimizu, T.; Frenking, G. Divalent E(0) Compounds (E = Si-Sn). Chem. Eur. J. 2009, 15, 8593-8604. (7) Takagi, N.; Frenking, G. Divalent Pb(0) Compounds. Theor. Chem. Acc. 2011, 129, 615-623. (8) Kinjo, R.; Donnadieu, B.; Celik, M. A.; Frenking, G.; Bertrand, G. Synthesis and Characterization of a Neutral Tricoordinate Organoboron Isoelectronic with Amines. Science 2011, 333, 610-613. (9) Braunschweig, H.; Dewhurst, R. D.; Hupp, F.; Nutz, M.; Radacki, K.; Tate, C. W.; Vargas, A.; Ye, Q. Multiple Complexation of CO and Related Ligands to a Main-Group Element. Nature 2015, 522, 327-330. (10) Zhang, Q. N.; Li, W. L.; Xu, C. Q.; Chen, M. H.; Zhou, M. F.; Li, J.; Andrada, D. M.; Frenking, G. Formation and Characterization of the Boron Dicarbonyl Complex B(CO)2-. Angew. Chem. Int. Ed. 2015, 54, 11078-11083. (11) Mondal, K. C.; Roesky, H. W.; Schwarzer, M. C.; Frenking, G.; Niepötter, B.; Wolf, H.; Herbst-Irmer, R.; Stalke, D. A Stable Singlet Biradicaloid Siladicarbene: (L:)2Si. Angew. Chem. Int. Ed. 2013, 52, 2963-2967. (12) Xiong, Y.; Yao, S.; Inoue, S.; Epping, J. D.; Driess, M. A Cyclic Silylone (“Siladicarbene”) with an Electron-Rich Silicon(0) Atom. Angew. Chem. Int. Ed. 2013, 52, 7147-7150.

14


Page 15 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(13) Tay, M. Q. Y.; Lu, Y.; Ganguly, R.; Vidović, D. A Carbone-Stabilized Two-Coordinate Phosphorus(III)-Centered Dication. Angew. Chem. Int. Ed. 2013, 52, 3132-3135. (14) Dordevic,

N.;

Ganguly,

R.;

Petkovic,

M.;

Vidovic,

D.

Bis(carbodicarbene)phosphenium Trication: The Case Against Hypervalency. Chem. Commun. 2016, 52, 9789-9792. (15) Xiong, Y.; Yao, S. L.; Tan, G. W.; Inoue, S.; Driess, M. A Cyclic Germadicarbene ("Germylone") from Germyliumylidene. J. Am. Chem. Soc. 2013, 135, 5004-5007. (16) Zhou,

Y.

P.;

Karni,

M.;

Yao,

S.;

Apeloig,

Y.;

Driess,

M.

A

Bis(silylenyl)pyridine Zero-Valent Germanium Complex and Its Remarkable Reactivity. Angew. Chem. Int. Ed. 2016, 55, 15096-15099. (17) Li, Y.; Mondal, K. C.; Roesky, H. W.; Zhu, H. P.; Stollberg, P.; Herbst-Irmer, R.; Stalke, D.; Andrada, D. M. Acyclic Germylones: Congeners of Allenes with a Central Germanium Atom. J. Am. Chem. Soc. 2013, 135, 12422-12428. (18) Frenking, G.; Hermann, M.; Andrada, D. M.; Holzmann, N. Donor-Acceptor Bonding in Novel Low-Coordinated Compounds of Boron and Group-14 Atoms C-Sn. Chem. Soc. Rev. 2016, 45, 1129-1144 (19) Frenking, G.; Tonner, R.; Klein, S.; Takagi, N.; Shimizu, T.; Krapp, A.; Pandey, K. K.; Parameswaran, P. New Bonding Modes of Carbon and Heavier Group 14 Atoms Si-Pb. Chem. Soc. Rev. 2014, 43, 5106-5139. (20) Kozma, A.; Gopakumar, G.; Fares, C.; Thiel, W.; Alcarazo, M. Synthesis and Structure of Carbene-Stabilized N-Centered Cations L2N+, [L2NR]2+, [LNR3]2+, and [L3N]3+. Chem. Eur. J. 2013, 19, 3542-3546 (21) Wilson, D. J. D.; Dutton, J. L. Recent Advances in the Field of Main-Group Mono- and Diatomic "Allotropes" Stabilised by Neutral Ligands. Chem. Eur. J. 2013, 19, 13626-13637. (22) Dyker, C. A.; Bertrand, G. Chemistry - Soluble Allotropes of Main-Group Elements. Science 2008, 321, 1050-1051. (23) Wang, Y.; Xie, Y. M.; Wei, P.; King, R. B.; Schaefer, H. F.; Schleyer, P. von R.; Robinson, G. H. A Stable Silicon(0) Compound with a Si=Si Double Bond. Science 2008, 321, 1069 –1071. (24) Wang, Y. Z.; Robinson, G. H. Carbene Stabilization of Highly Reactive Main-Group Molecules. Inorg. Chem. 2011, 50, 12326-12337.

15



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(25) Wang, Y. Z.; Robinson, G. H. Carbene-Stabilized Main Group Diatomic Allotropes. Dalton Trans. 2012, 41, 337-345. (26) Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond. Science 2012, 336, 1420-1422. (27) Georgiou, D. C.; Stringer, B. D.; Hogan, C. F.; Barnard, P. J.; Wilson, D. J. D.; Holzmann, N.; Frenking, G.; Dutton, J. L. The Fate of NHC-Stabilized Dicarbon. Chem. Eur. J. 2015, 21, 3377-3386. (28) Sidiropoulos, A.; Jones, C.; Stasch, A.; Klein, S.; Frenking, G. N-Heterocyclic Carbene Stabilized Digermanium(0). Angew. Chem. Int. Edit. 2009, 48, 9701-9704. (29) Jones, C.; Sidiropoulos, A.; Holzmann, N.; Frenking, G.; Stasch, A. An N-Heterocyclic Carbene Adduct of Diatomic Tin, Sn = Sn. Chem. Commun. 2012, 48, 9855-9857. (30) Wang, Y. Z.; Xie, Y. M.; Wei, P. R.; King, R. B.; Schaefer, H. F.; Schleyer, P. V.; Robinson, G. H. Carbene-Stabilized Diphosphorus. J. Am. Chem. Soc. 2008, 130, 14970- 14971. (31) Abraham, M. Y.; Wang, Y. Z.; Xie, Y. M.; Wei, P. R.; Schaefer, H. F.; Schleyer, P. V.; Robinson, G. H. Carbene Stabilization of Diarsenic: From Hypervalency to Allotropy. Chem. Eur. J. 2010, 16, 432-435. (32) Jin, J. Y.; Wang, G. J.; Zhou, M. F.; Andrada, D. M.; Hermann, M.; Frenking, G. The B3(NN)3+ and B3(CO)3+ Complexes Featuring the Smallest -Aromatic Species B-3(+). Angew. Chem. Int. Ed. 2016, 55, 2078-2082. (33) Alcarazo, M.; Lehmann, C. W.; Anoop, A.; Thiel, W.; Furstner, A. Coordination Chemistry at Carbon. Nat. Chem. 2009, 1, 295-301. (34) Frenking, G. Dative Bonds in Main-Group Compounds: A Case for More Arrows! Angew. Chem. Int. Ed. 2014, 53, 6040-6046. (35) Holzmann, N.; Dange, D.; Jones, C.; Frenking, G. Dinitrogen as Double Lewis Acid: Structure and Bonding of Triphenylphosphinazine N2(PPh3)2. Angew. Chem. Int. Ed. 2013, 52, 3004-3008. (36) Diels, O; Wolf, B. Ueber das Kohlensuboxyd. I. Ber. Dt. Chem. Ges., 1906, 39, 689-697. (37) Kappe, T.; Ziegler, E. Carbon Suboxide in Preparative Organic Chemistry. Angew. Chem., Int. Ed. Engl., 1974, 13, 491-504.

16


Page 16 of 28

Page 17 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(38) Jensen, P.; Johns, J. W. C. The Infrared Spectrum of Carbon Suboxide in the 6 Fundamental Region-Experimental Observation and Semirigid Bender Analysis. J. Mol. Spectrosc. 1986, 118, 248-266. (39) Koput, J. An Ab Initio Study on the Equilibrium Structure and CCC Bending Energy Levels of Carbon Suboxide. Chem. Phys. Lett. 2000, 320, 237-244. (40) Tonner, R.; Heydenrych, G.; Frenking, G. First and Second Proton Affinities of Carbon Bases. ChemPhysChem. 2008, 9, 1474-1481. (41) Tortajada, J.; Provot, G.; Morizur, J. P.; Gal, J. F.; Maria, P. C.; Flammang, R.; Govaert, Y. Experimental and Theoretical Study of Carbon Suboxide C3O2, Protonated Carbon Suboxide C3HO2+ and C3HO2 Radical in the Gas Phase. Int. J. Mass Spectrom. 1995, 141, 241-255. (42) Pandolfo, L.; Paiaro, G.; Somogyi, A.; Catinella, S.; Traldi, P. On the Gas Phase Reaction of C3O2+ with C3O2. Org. Mass Spectrom. 1994, 29, 540-546. (43) Douglas, A. E.; Herzberg, G. CH+ in Interstellar Space and in the Laboratory. Astrophys. J. 1941, 94, 381-381. (44) Smith, D. The Ion Chemistry of Interstellar Clouds. Chem. Rev. 1992, 92, 1473-1485. (45) Huntress, W.; Alien, M.; Delrtsky, M. Carbon Suboxide in Comet Halley? Nature 1991, 352, 316-318. (46) Wang, G. J.; Chi, C. X.; Xing, X. P.; Ding, C. F.; Zhou, M. F. A Collinear Tandem Time-of-Flight Mass Spectrometer for Infrared Photodissociation Spectroscopy of Mass-Selected Ions. Sci. China Chem. 2014, 57, 172-177. (47) Bartlett, R. J.; Musial, M. Coupled-Cluster Theory in Quantum Chemistry. Rev. Mod. Phys. 2007, 79, 291-352. (48) Dunning, T. H. Gaussian Basis Sets for Use in Correlated Molecular Calculations. 1. The Atoms Boron Through Neon and Hydrogen. J. Chem. Phys. 1989, 90, 1007-1023. (49) Werner, H. J.; Knowles, P. J.; Knizia,G.; Manby, F. R.; Schütz, M.; Celani, P.; Korona, T.; Lindh, R.; Mitrushenkov, A.; Rauhut, G.et al. http://www.molpro.net (2012). (50) Becke, A. D. Density Functional Exchange Energy Approximation with Correct Asymptotic Behavior. Phys. Rev. A 1988, 38, 3098-3100. (51) Perdew, J. P. Density Functional Approximation for the Correction Energy of

17



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

the Inhomogeneous Electron Gas. Phys. Rev. B 1986, 33, 8822-8824. (52) Snijders, J. G.; Vernooijs, P.; Baerends, E. J. Roothaan-Hartree-Fock-Slater Atomic Wave Functions. Atomic Data and Nuclear Data Tables 1981, 26, 483-509. (53) Krijn, E. J. B. Fit Functions in the HFS-Method; Vrije Universiteit Amsterdam: The Netherlands, 1984. (54) te Velde, G.; Bickelhaupt, F. M.; Baerends, E. J.; Fonseca Guerra, C.; van Gisbergen, S. J. A.; Snijders, J. G.; Ziegler, T. Chemistry with ADF. J. Comput. Chem. 2001, 22, 931-967. (55) ADF2013, SCM, Theoretical Chemistry, Vrije Universiteit Amsterdam, The Netherlands, http://www.scm.com. (56) Morokuma, K. Molecular Orbital Studies of Hydrogen Bonds. 3. C=O H-O Hydrogen Bond in H2CO-H2O and H2CO-2H2O. J. Chem. Phys. 1971, 55, 12361244. (57) Ziegler, T.; Rauk, A. CO, CS, N2, PF3, and CNCH3 as Sigma-Donors and Pi-Acceptors-Theoretical Study by the Hartree-Fock Slater Transition State Method. Inorg. Chem. 1979, 18, 1755-1759. (58) Bickelhaupt, F. M.; Baerends, E. J. Kohn-Sham Density Functional Theory: Predicting and Understanding Chemistry. In Reviews in Computational Chemistry, Vol 15, Lipkowitz, K. B.; Boyd, D. B. Eds. Wiley-VCH, Inc: New York, 2000, Vol. 15, pp 1-86. (59) Frenking, G.; Wichmann, K.; Frohlich, N.; Loschen, C.; Lein, M.; Frunzke, J.; Rayon, V. M. Towards a Rigorously Defined Quantum Chemical Analysis of the Chemical Bond in Donor-Acceptor Complexes. Coord. Chem. Rev. 2003, 238, 55-82. (60) Lein, M.; Frenking, G. In Theory and Applications of Computational Chemistry: The First 40 Years. Dykstra, C. E.; Frenking, G.; Kim, K. S.; Scuseria, G. E. Eds. Elsevier: Amsterdam, 2005, pp 367-414. (61) Krapp, A.; Bickelhaupt, F. M.; Frenking, G. Orbital Overlap and Chemical Bonding. Chem. Eur. J. 2006, 12, 9196-9216. (62) Frenking, G.; Bickelhaupt, F. M. The Chemical Bond. 1. Fundamental Aspects of Chemical Bonding, Frenking, G.; Shaik, S. Eds. Wiley-VCH, Weinheim, 2014, pp 121-158. (63) Mitoraj, M. P.; Michalak, A.; Ziegler, T. A Combined Charge and Energy

18


Page 18 of 28

Page 19 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Decomposition Scheme for Bond Analysis. J. Chem. Theory Comput. 2009, 5, 962-975. (64) Mitoraj, M.; Michalak, A. Donor-Acceptor Properties of Ligands from the Natural Orbitals for Chemical Valence. Organometallics 2007, 26, 6576-6580. (65) Mitoraj, M.; Michalak, A. Applications of Natural Orbitals for Chemical Valence in a Description of Bonding in Conjugated Molecules. J. Mol. Model. 2008, 14, 681-687. (66) Okumura, M.; Yeh, L. I.; Myers, J. D.; Lee, Y. T. Infrared Spectra of the Cluster Ions H7O3+·H2 and H9O4+·H2. J. Chem. Phys. 1986, 85, 2328-2329 (67) Bieske, E. J.; Dopfer, O. High-Resolution Spectroscopy of Cluster Ions. Chem. Rev. 2000, 100, 3963-3998. (68) Robertson, W. H.; Johnson, M. A. Molecular Aspects of Halide Ion Hydration: The Cluster Approach. Annu. Rev. Phys. Chem. 2003, 54, 173-213. (69) Duncan, M. A. Infrared Spectroscopy to Probe Structure and Dynamics in Metal Ion-Molecule Complexes. Int. Rev. Phys. Chem. 2003, 22, 407-435. (70) Rabalais, J. W.; Werme, L. O.; Bergmark, T.; Karlsson, L.; Hussain, M.; Siegbahn, K. Electron Spectroscopy, Shirley, D. A. Eds. North-Holland Publishing Co.; Amsterdam, 1972, p425. (71) Hakalla, R.; Kepa, R.; Szajna, W.; Zachwieja, M. New Analysis of the Douglas-Herzberg System (A1- X 1+) in the CH+ Ion Radical - The A1- X 1 +

 System in the CH+. Eur. Phys. J. D 2006, 38, 481-488.

(72) Bembenek, Z.; Cisak, H.; Kepa, R. New Spectroscopic Analysis of the A 1 Π - X 1 +

Σ Band System of the CD + Radical. J. Phys. B 1987, 20, 6197- 6205.

(73) Tonner, R.; Frenking, G. Divalent Carbon(0) Chemistry, Part 1: Parent Compounds. Chem. Eur. J. 2008, 14, 3260-3272. (74) Cremer, D.; Wu, A. N.; Larsson, A.; Kraka, E. Some Thoughts About Bond Energies, Bond Lengths, and Force Constants. J. Mol. Model. 2000, 6, 396-412. (75) Kaupp, M.; Metz, B.; Stoll, H. Breakdown of Bond Length-Bond Strength Correlation: A Case Study. Angew. Chem. Int. Ed. 2000, 39, 4607- 4609. (76) Merrick, J. P.; Moran, D.; Radom, L. An Evaluation of Harmonic Vibrational Frequency Scale Factors. J. Phys. Chem. A 2007, 111, 11683-11700. (77) Andrada, D. M.; Frenking, G. Stabilization of Heterodiatomic SiC Through Ligand Donation: Theoretical Investigation of SiC(L)2 (L = NHCMe, CAAC(Me),

19



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

PMe3). Angew. Chem. Int. Ed. 2015, 54, 12319-12324. (78) Celik, M. A.; Frenking, G.; Neumuller, B.; Petz, W. Exploiting the Two-Fold Donor Ability of Carbodiphosphoranes: Theoretical Studies of [(PPh3)2CEH2]q (Eq=Be, B+, C2+, N3+, O4+) and Synthesis of the Dication [(Ph3P)2C=CH2]2+. ChemPlusChem. 2013, 78, 1024-1032. (79) Krapp, A.; Pandey, K. K.; Frenking, G. Transition Metal-Carbon Complexes. A Theoretical Study. J. Am. Chem. Soc. 2007, 129, 7596-7610.

20


Page 20 of 28

Page 21 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Captions and legends

Figure 1. Infrared photodissociation spectrum of the [C3O2·Ar]+ cation complex.

Figure 2. Infrared photodissociation spectra of the (a) [HC3O2·CO]+ and (b) [DC3O2·CO]+ cation complexes.

Figure 3. Optimized geometries at CCSD(T)/cc-pVTZ of (a) C3O2+, (b) [C3O2·Ar]+, (c) HC3O2+, (d) DC3O2+, (e) [HC3O2·CO]+, (f) [DC3O2·CO]+. Interatomic distances are given in Å, angles in degree.

Figure 4. (a) - (c) Plot of deformation densities Δρ1-3 with the connected stabilization energies ΔE1-3 of the pairwise orbital interactions in HC3O2+ (left column) and the associated occupied and vacant fragment orbitals (middle and right columns) in the electronic singlet state. (d) Plot of deformation densities Δρ1-3 with the connected stabilization energies ΔE1-3 of the pairwise orbital interactions in C3O2+. The direction of the charge flow is red→blue.

21



10

8

6 Intensity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 28

4

2

0 1800

1900

2000

2100

2200

2300

-1

Wavenumber / cm

Figure 1

22


Page 23 of 28

30

20 Intensity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a) 10

(b) 0 1800

2100

2400

2700

3000

3300

3600

-1

Wavenumber (cm )

Figure 2

23



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

B1 C(CO)2+ (C2v) De (2 CO) = 152.1 kcal/mol (a) 2

A1 HC(CO)2+ (C2V) De (H) = 120.8 kcal/mol De (2 CO) = 176.5 kcal/mol (c) 1

1

A1 [HC3O2·CO]+ (C2v)

Page 24 of 28

2

A' [C3O2·Ar]+ (Cs) De (Ar) = 2.0 kcal/mol (b)

A1 DC(CO)2+ (C2V) De (D) = 120.8 kcal/mol De (2 CO) = 176.5 kcal/mol (d) 1

1

De (CO) = 6.1 kcal/mol

A1 [DC3O2·CO]+ (C2v)

De (CO) = 6.1 kcal/mol

(e)

(f) Figure 3

24


Page 25 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


HC3O2+ Orbitals CH+

Deformation density Δρ

Orbitals (CO)2

(a)

∆E1 =-267.5 kcal/mol

LUMO ( = -19.5 eV)

HOMO-1 (  = -10.5 eV)

∆E2 = -216.4 kcal/mol

LUMO+1 ( = -15.7 eV)

HOMO (  = -7.2 eV)

∆E3 = -70.2 kcal/mol

HOMO (  = -15.3 eV) C3O2+

LUMO+3 (  = -2.6 eV)

Δρ1

(b)

Δρ2

(c)

Δρ3

Deformation density Δρ

(d)

∆E1 = -451.9 kcal/mol

∆E2= -240.7 kcal/mol

∆E3 = -26.3 kcal/mol

Figure 4

25



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 28

Table 1. Experimental and Calculated (CCSC(T)/cc-pVTZ) Vibrational Frequencies ν and Frequency Shiftsa Δν (cm-1) of the [C3O2·Ar]+, [HC3O2·CO]+ and [DC3O2·CO]+ Cations.

mode

[C3O2·Ar]+

[HC3O2·CO]+

[DC3O2·CO]+

a

Exptl.

Calcd.

ν

Δν

ν

Δν

sym. CO str.

2168

···

2223

···

asym. CO str.

2096

···

2169

···

C-H str.

3044

···

3183

···

sym. CO str.

2292

124

2327

104

asym. CO str.

2208

112

2244

75

C-D str.

2306

···

2367

···

sym. CO str.

2262

96

2313

90

asym. CO str.

2200

104

2245

76

The frequency shifts Δν are given wrt to [C3O2·Ar]+.

26


Page 27 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table 2. EDA-NOCV Calculations at the BP86/TZ2P+//CCSD(T)/cc-pVTZ Level of C3O2+ and HC(CO)2+. Energy Values are Given in kcal/mol. Fragments

(2P) C+ (2s22p0 2p||0 2p1)

(1Δ) CH+

(CO)2 Singlet

(CO)2 Singlet

∆Eint

-210.6

-384.7

∆EPauli

831.5

368.1

∆Eelstata

-221.8 (21.3 %)

-137.4 (18.3 %)

∆Eorba

-820.3 (78.7 %)

-615.4 (81.7 %)

∆Eσ OC→X+←COc (+,+) donationb

-451.9 (55.1 %)

-267.5 (43.5 %)

∆Eσ OC→X+←COc (+,-) donationb

-240.7 (29.3 %)

-216.4 (35.2 %)

-26.3 (3.2 %)

-70.2 (11.3 %)

-101.4 (12.4 %)

-61.3(10.0 %)

∆Eπ OC←X+→COc π-backdonationb ∆Erestb

a

The values in parentheses give the percentage contribution to the total attractive

interactions ΔEelstat + ΔEorb. b

The values in parentheses give the percentage contribution to the total orbital

interactions ΔEorb. X = C in case of C3O2+; X = CH in case of HC(CO)2+.

c

27



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

TOC graphic

+

+

C(CO)2

HC(CO)2

28


Page 28 of 28

Dicarbonyls of Carbon and Methylidyne Cations - The Journal of

Recommend Documents