Geometry Optimization and Energetics Analysis of Linear C10 and Cyclo[10]carbon structures via ab initio methods
Disciplines
Computational Chemistry | Materials Chemistry | Physical Chemistry
Abstract (300 words maximum)
The first successful synthesis of cyclo[10]carbon structures was recently discovered to be possible via the tip-induced dehalogenation of octachloronaphthalene, C10Cl8 deposited on the interface of a sodium chloride and gold (III) crystal. Previous research revealed characterizations of the C10 molecular structure using the atomic force microscope (AFM) and simulated AFM images. Cyclo[10]carbon is proposed to transition between cumulene-like circular (D10h) and pentagonal (D5h) structures. However, a discrepancy exists surrounding the difference in energy between the two structures, which has been a debate in literature. The second order Møller–Plesset perturbation theory, MP2 asserts that the circular ring exists in lower relative energy; whereas the pentagonal structure in coupled-cluster, CCSD(T), and density functional theory (DFT) methods resulted in lower energy. These structures exhibit double aromaticity, with orthogonal (in- and out-of-plane) π systems. In this work, DFT calculations have been carried out using the Gaussian16 quantum chemistry package and coupled-cluster, CCSD(T) methods with the Molpro quantum chemistry package. Multiple methods including Becke 3-Parameter Lee-Yang-Parr (B3LYP), exchange-correlation density functionals (tau-HCTH), and Truhlar’s density functionals (M06L) were used in conjunction with aug-cc-pVDZ, cc-pVTZ, aug-cc-pVTZ, and cc-pVQZ [zeta-functionalized] basis sets. Data for intrinsic reaction coordinates (IRC), frontier orbitals (FOs) have been visualized in GaussView06, while Mulliken population analysis and atomization energies were completed with Gaussian16. We compared the barrier heights of D5h – D10h isomerization with data in the literature to validate the accuracy of new theoretical methods for fitting the potential energy surfaces. Cyclo [10]carbon calculations imply that the pentagonal D5h isomer is lower in energy with barrier heights ~ 0.3 kcal/mol. The IRC calculations confirm that the D10h ring is the transition state between two different inversions of the pentagonal cyclo[10]carbon. Furthermore, triplet state calculations elucidate a lower energy with a marquise-shaped structure. FO calculations suggest that this stretching allows the π-system to achieve a state of aromatic conjugation, lowering the overall energy.
Academic department under which the project should be listed
CSM - Chemistry and Biochemistry
Primary Investigator (PI) Name
Martina Kaledin
Geometry Optimization and Energetics Analysis of Linear C10 and Cyclo[10]carbon structures via ab initio methods
The first successful synthesis of cyclo[10]carbon structures was recently discovered to be possible via the tip-induced dehalogenation of octachloronaphthalene, C10Cl8 deposited on the interface of a sodium chloride and gold (III) crystal. Previous research revealed characterizations of the C10 molecular structure using the atomic force microscope (AFM) and simulated AFM images. Cyclo[10]carbon is proposed to transition between cumulene-like circular (D10h) and pentagonal (D5h) structures. However, a discrepancy exists surrounding the difference in energy between the two structures, which has been a debate in literature. The second order Møller–Plesset perturbation theory, MP2 asserts that the circular ring exists in lower relative energy; whereas the pentagonal structure in coupled-cluster, CCSD(T), and density functional theory (DFT) methods resulted in lower energy. These structures exhibit double aromaticity, with orthogonal (in- and out-of-plane) π systems. In this work, DFT calculations have been carried out using the Gaussian16 quantum chemistry package and coupled-cluster, CCSD(T) methods with the Molpro quantum chemistry package. Multiple methods including Becke 3-Parameter Lee-Yang-Parr (B3LYP), exchange-correlation density functionals (tau-HCTH), and Truhlar’s density functionals (M06L) were used in conjunction with aug-cc-pVDZ, cc-pVTZ, aug-cc-pVTZ, and cc-pVQZ [zeta-functionalized] basis sets. Data for intrinsic reaction coordinates (IRC), frontier orbitals (FOs) have been visualized in GaussView06, while Mulliken population analysis and atomization energies were completed with Gaussian16. We compared the barrier heights of D5h – D10h isomerization with data in the literature to validate the accuracy of new theoretical methods for fitting the potential energy surfaces. Cyclo [10]carbon calculations imply that the pentagonal D5h isomer is lower in energy with barrier heights ~ 0.3 kcal/mol. The IRC calculations confirm that the D10h ring is the transition state between two different inversions of the pentagonal cyclo[10]carbon. Furthermore, triplet state calculations elucidate a lower energy with a marquise-shaped structure. FO calculations suggest that this stretching allows the π-system to achieve a state of aromatic conjugation, lowering the overall energy.