Factors contributing to phantom bonds in inorganic molecules: Interpretations and predictions

Rathna, A.; Chandrasekhar, Jayaraman

doi:10.1007/bf02911090

Cited by 3 publications

(2 citation statements)

References 24 publications

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“…A structure sandwiched between 6-membered rings is denoted as a 6−6 bond, and a structure sandwiched between a 6-membered ring and a 5-membered one is denoted as a 6−5 bond. 47 All 60 carbon atoms are equivalent. As a result, there is only one type of substitutional doping site in C 60 .…”

Section: ■ Methodsmentioning

confidence: 99%

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B-Doped Fullerene as a Potential Metal-Free Catalyst Material for CO Reduction Reaction

Ridassepri,

Umejima,

Nakamura

2024

J. Phys. Chem. C

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Reducing carbon monoxide (CO) plays an essential role in the goal of C1 chemistry. This study aims to design and develop B-doped fullerenes as the electrocatalyst for the CO reduction reaction using first-principles calculations based on density functional theory. The computational hydrogen electrode model has been employed to evaluate the catalytic properties of Bdoped fullerene. It has been confirmed that the CO molecule adsorbs stably on C 59 B with an adsorption energy of −0.35 eV. When an external voltage of 0.39 V, the overvoltage, is applied, all reactions proceed downhill, selectively producing methane in an acidic environment. This value is sufficiently lower than previously reported values on metal surfaces. The reaction process to determine the overvoltage is the initial hydrogenation process, *CO → *CHO. On the other hand, the CO molecule does not adsorb on a flat B-doped graphene nanocluster, implying that the curvature of the carbon network plays an important role in CO adsorption. Thus, we have investigated the dependence of the radius of the curvature on the adsorption energy and the overvoltage using a different size of fullerene, C 69 B. The reaction site with a radius of curvature of 4.86 Å for C 69 B has a minimum overvoltage of 0.26 V. However, the adsorption energy of CO molecules is −0.12 eV, higher than that of C 59 B. This suggests the existence of an optimal radius of curvature for various applications. The curvature of the fullerene surface plays an important role as a catalyst for the CO reduction. This research will pave the way for developing catalytic properties of surfaces with curvature.

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Section: ■ Methodsmentioning

confidence: 99%

“…There are two types of bonds in pristine C 60 . A structure sandwiched between 6-membered rings is denoted as a 6–6 bond, and a structure sandwiched between a 6-membered ring and a 5-membered one is denoted as a 6–5 bond . All 60 carbon atoms are equivalent.…”

Section: Methodsmentioning

confidence: 99%

B-Doped Fullerene as a Potential Metal-Free Catalyst Material for CO Reduction Reaction

Ridassepri,

Umejima,

Nakamura

2024

J. Phys. Chem. C

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Donor‐Stabilized 1,3‐Disila‐2,4‐diazacyclobutadiene with a Nonbonded Si⋅⋅⋅Si Distance Compressed to a Si=Si Double Bond Length

et al. 2016

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Ad onor-stabilized 1,3-disila-2,4-diazacyclobutadiene presents an exceptionally short nonbonded Si···Si distance (2.23 ), which is as short as that of Si=Si bonds (2.15-2.23 ). Theoretical investigations indicate that there is no bond between the two silicon atoms,a nd that the unusual geometry can be related to as ignificant coulomb repulsion between the two ring nitrogen atoms.T his chemical pressure phenomenon could provide an alternative and superior way of squeezing out van der Waals space in highly strained structures, as compared to the classical physical methods.Two atoms approaching within ad istance shorter than the sum of van der Waals radii, without bonding interactions, results in significant repulsion. High pressure can force molecules to approach each other, thus violating the van der Waals space. [1] Such high compression of molecules,which leads to intermolecular overlaps of molecular orbitals, induces,i ns ome cases,u nique physical phenomena such as metallization of neutral molecules (i.e., O 2 at 95 GPa, SiH 4 at 91 GPa, N 2 Op redicted above 177 GPa). [2][3][4][5] Endohedral confinement of atoms within small cage compounds also leads to unusual nonbonded structures with short internuclear distances. [6] Indeed, two atoms of He in C 60 were predicted to exist as weakly bonded van der Waals complexes,H e 2 @C 60 (see Figure 3a), [7] and asmaller hydrocarbon cage,C 20 H 20 ,can force two He atoms to ah igh-energy structure in which the He···He distance is two times smaller than the van der Waals radius of helium. [8] However under these conditions,i na ny case,n onbonded interatomic distances never approached alength as short as that of acovalent single bond.An exception is the nonbonded Si···Si dihedral distance (2.31 )found in the 1,3-diosiloxane I,and it is even shorter than Si À Si covalent bonds (2.36 ). [9][10][11] Computational calculations have predicted an even shorter Si···Si distance (2.06 )for the related bicyclic molecule II. [12] Theelectronic origin of the exceptionally short nonbonded distances,called a"phantom bond", has been the subject of many experimental and theoretical investigations [13] and several models with particular orbital interactions [unsupported p-bond model, [14,15] s-bridged p-bonding model, [16] and cyclic (n,d,d) delocalization model [17] ]h ave been proposed to explain the unusual geometry of 1,3-disiloxanes.A lternatively,t he ring deformation resulting from the elongation of the O···O diagonal distance arising from the electrostatic repulsion was also considered. [1a] Several related four-membered cyclic compounds (III)a re also known to deform to diamondshaped patterns for the same reason, [18][19][20] although they do not exhibit adiagonal distance shorter than acovalent single bond. [15a, 21] In spite of these theoretical studies,none of them are supported by experimental evidence.The lack of available molecules,o ther than 1,3-disiloxanes,h as limited further discussion. Here we report the synthesis of the phosphinestabilized 1,3-disila-2,4-diazacycl...

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Donor‐Stabilized 1,3‐Disila‐2,4‐diazacyclobutadiene with a Nonbonded Si⋅⋅⋅Si Distance Compressed to a Si=Si Double Bond Length

et al. 2016

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A donor-stabilized 1,3-disila-2,4-diazacyclobutadiene presents an exceptionally short nonbonded Si⋅⋅⋅Si distance (2.23 Å), which is as short as that of Si=Si bonds (2.15-2.23 Å). Theoretical investigations indicate that there is no bond between the two silicon atoms, and that the unusual geometry can be related to a significant coulomb repulsion between the two ring nitrogen atoms. This chemical pressure phenomenon could provide an alternative and superior way of squeezing out van der Waals space in highly strained structures, as compared to the classical physical methods.

show abstract

Factors contributing to phantom bonds in inorganic molecules: Interpretations and predictions

Cited by 3 publications

References 24 publications

B-Doped Fullerene as a Potential Metal-Free Catalyst Material for CO Reduction Reaction

B-Doped Fullerene as a Potential Metal-Free Catalyst Material for CO Reduction Reaction

Donor‐Stabilized 1,3‐Disila‐2,4‐diazacyclobutadiene with a Nonbonded Si⋅⋅⋅Si Distance Compressed to a Si=Si Double Bond Length

Donor‐Stabilized 1,3‐Disila‐2,4‐diazacyclobutadiene with a Nonbonded Si⋅⋅⋅Si Distance Compressed to a Si=Si Double Bond Length

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