Calculation of bond lengths and angles of hydrocarbons by the iterative MOA [maximum overlap approximation] method

Kovačević, K.; Maksić, Zvonimir B.

doi:10.1021/jo00918a026

Cited by 87 publications

(23 citation statements)

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“…§ Calculated using %s =0.20 ~JcH (Muller & Pritchard, 1959). ¶ lterative molecular-orbital overlap (IMOA) method: Kovacevic & Maksic (1974);Eckert-Maksic & Maksic (1982).…”

Section: Exocyclic Bondingmentioning

confidence: 99%

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The geometry of small rings. VI. Geometry and bonding in cyclobutane and cyclobutene

Allen¹

1984

Acta Crystallogr Sect B

105

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The molecular geometry, obtained by X-ray methods (R-< 0.10) for 202 derivatives of cyclobutane and 21 derivatives of cyclobutene, has been analysed via the Cambridge Structural Database. For c yclobutane a mean ring bond length (d) of 1.554 (1) A is obtained, but the range (1-521-1.606 A,) is wide; this is attributable to the numbers (n~, n2) of exocyclic non-H substituents on a ring bond C(1)-C(2). For nl or n2 = 0, d = 1.547 (2) A, but d increases to 1.575 (3) A, for n~ = n2 = 2. Puckered conformations are preferred in the range 20 < ¢ < 35 °, although a complete range to 67.2 ° is represented. Whilst d is marginally longer for planar rings at 1.558(3) A,, a constant d of 1.553 (1)A, is observed as ¢ increases from 5 ° and the ring valence angle (0) decreases from 90 °. Thus the transannular C-C distance must decrease and is 2.205(4)A, at ~=0 °, 0=90 °, and 2.107(13) A, at ~ = 45 °, 0 =85.5 °. Increased transannular non-bonded repulsions are balanced by a decrease in these forces between vicinal 1,2-substituents. The substituentsubstituent torsion angle must increase from 0 ° (eclipsed) as ~ increases, and the effect is enhanced by inward rocking of the methylene groups by ---0-12 ¢. Each ring C atom uses hybrids of -27% s character for exocyclic bond formation and of -23% s character to form the ring cr framework. Ring bonds are bent by ca 9 °, compared with 22 ° in cyclopropane. Results for cyclobutene are restricted by the small data set. The C-C bonds, at 1.514(2) and 1.573 (4)A, are comparable with gas-phase results, but an unconjugated double bond of 1.323 (4)A, is relatively short.

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“…§ Calculated using %s =0.20 ~JcH (Muller & Pritchard, 1959). ¶ lterative molecular-orbital overlap (IMOA) method: Kovacevic & Maksic (1974);Eckert-Maksic & Maksic (1982).…”

Section: Exocyclic Bondingmentioning

confidence: 99%

“…§ Taken from Breitmaier & Voelter (1978). ¶ See footnote § of Table 8. II Kovacevic & Maksic (1974). Eckert-Maksic & Maksic (1982).…”

Section: Ring Geometrymentioning

confidence: 99%

The geometry of small rings. VI. Geometry and bonding in cyclobutane and cyclobutene

Allen¹

1984

Acta Crystallogr Sect B

105

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“…The deviation angles in C,, and C,, clusters are the largest in value, but these angles are still smaller than that of 26.8" in cyclopropene [8]. The average deviation angles in C, and C,,, are smaller and equal, respectively, to the deviation angle of the double bond in cyclobutene (13.3') [4].…”

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confidence: 84%

“…The clusters studied are CZ4, C,,, C, , and Ciz0, which have the shape of the truncated octahedron, truncated cuboctahedron, truncated icosahedron, and truncated icosidodecahedron, respectively. The shapes of these clusters together with the enumeration of their atoms are depicted in Figure 1.The method used is the iterative maximum overlap approximation (IMOA) [4]. It considers the orthogonal local hybrid orbitals…”

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confidence: 99%

On the hybridization in some archimedean carbon clusters

Kovačević

Graovac

Babić

1987

Int. J. Quantum Chem.

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Hybridization, bond, and deviation angles as well as strain energies in Archimedean carbon clusters C,,, C,*, C,,, and CI2, are calculated within the iterated maximum overlap approximation.Recent laser irradiation experiments on graphite performed by Kroto et al.[ 11 have given rise to speculations on the existence of the stable cluster of 60 carbon atoms. It has been suggested that this cluster has the form of one of the Archimedean solids, namely that of a truncated icosahedron. The chemical name buckminsterfullerene was suggested for this cluster [ 1,2]. All atoms in buckminsterfullerene have a valency of three. In the present note we have studied hybridization, bond, and deviation angles in buckminsterfullerene and some other carbon clusters having in common the Archimedean lattice with the same valency condition [3]. The clusters studied are CZ4, C,,, C, , and Ciz0, which have the shape of the truncated octahedron, truncated cuboctahedron, truncated icosahedron, and truncated icosidodecahedron, respectively. The shapes of these clusters together with the enumeration of their atoms are depicted in Figure 1.The method used is the iterative maximum overlap approximation (IMOA) [4]. It considers the orthogonal local hybrid orbitalswhere the hybridization parameters, nAi = (1 -u~J / u~~, are varied until the maximum of the sum Eb of the weighted overlap integrals is attained Since the clusters studied here are constructed from carbon atoms only, the sum Eb simplifies to

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“…Distortions from cubic symmetry are of interest. Although various theoretical studies of the cubane geometry have been reported (1)(2)(3)(4), no structure determinations of cubane derivatives other than that of cubane itself ( 5 ) are available.…”

Section: Introductionmentioning

confidence: 99%

The structure of cubane mono and 1,4-dicarboxylic acids in lyotropic liquid crystalline solution

Tracey¹

1984

Can. J. Chem.

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ALAN S. TRACEY. Can. J. Chem. 62, 101 (1984). Proton nmr studies of cubane mono and 1,4-dicarboxylic acids in lyotropic liquid crystalline solution show that these molecules are distorted from the cubane structure. The protons of cubane dicarboxylate which are vicinal to their respective carboxylate group are displaced towards those groups along the C 3 axis resulting in an elongation relative to a cube. In cubane monocarboxylate there is also a displacement of vicinal protons toward the carboxyl group, but this is accompanied by a displacement of the protons one carbon further removed, away from the carboxyl groups. The shape of this latter compound is comparable to that of a section of a cone with the narrow end of the cone defining the proton positions adjacent to the carboxyl group while the wide end of the cone defines the positions of the adjacent set of protons. The remaining proton of course sits on the C 3 axis which determines the centre of symmetry of the cone. ALAN S. TRACEY. Can. J. Chem. 62, 101 (1984). Les Ctudes en rmn du proton des acides mono et dicarboxyliques-1.4 du cubane dans un cristal liquide lyotrope rkvklent que ces molCcules sont dtformCes par rapport a la structure du cubane. Les protons du dicarboxylate de cubane qui sont vicinaux avec leur groupe carboxylate respectif se dCplacent vers les groupes le long de I'axe C , provoquant une elongation par rapport au cubane. Dans le monocarboxylate de cubane, il y a tgalement un deplacement des protons vicinaux vers le groupe carboxyle; mais ce dCplacement des protons vicinaux s'accompagne aussi d'un dCplacement des protons qui sont sur la position suivante par rapport aux groupes carboxyles. La forme de ce dernier composC est comparable a celle d'une section d'un cane avec I'extrCmitC Ctroite du cbne dkfinissant la position du proton adjacent au groupe carboxyle tandis que I'extrtmitC plus large du cbne dCfinit les positions des ensembles de protons adjacents. Le proton restant se situe naturellement sur l'axe C 3 qui dktermine le centre de symCtrie du cbne.[ (cu-

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Calculation of bond lengths and angles of hydrocarbons by the iterative MOA [maximum overlap approximation] method

Cited by 87 publications

References 1 publication

The geometry of small rings. VI. Geometry and bonding in cyclobutane and cyclobutene

The geometry of small rings. VI. Geometry and bonding in cyclobutane and cyclobutene

On the hybridization in some archimedean carbon clusters

The structure of cubane mono and 1,4-dicarboxylic acids in lyotropic liquid crystalline solution

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