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Minyaev, R. M.; Gribanova, T. N.; Starikov, А. G.; Минкин, Владимир И.

doi:10.1023/a:1014429323457

Cited by 50 publications

(31 citation statements)

References 7 publications

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“…16a,c,e Although none of these species is the global minimum on the potential‐energy surfaces, it has been suggested that they may be viable experimentally. The two proposed hexa‐ and heptacoordinate carbon species are D 6 h CB 6 2− 13a,b,d, 14c, 15 and D 7 h CB 7 − ,13b, 14c respectively. The CB 7 − species is isoelectronic to B 8 2− , which we have shown previously to have a global‐minimum D 7 h structure with a heptacoordinate boron atom 17–20.…”

Section: Comparison Of the Experimental Vdes Of Cb7− To The Calculatementioning

confidence: 99%

CB₇⁻: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon

et al. 2007

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In organic chemistry, saturated carbon is known to bond to four ligands tetrahedrally, as first recognized independently by J. H. vant Hoff and J. A. Le Bel in 1874. However, after the proposal by Hoffmann and co-workers of tetracoordinate planar carbon in 1970, [1] extensive experimental and theoretical efforts were made to search for so-called anti-vant Hoff/ anti-Le Bel molecules (for recent reviews, see references [2][3][4]). In particular, the first experimental and theoretical realization of pentaatomic planar-coordinated carbon species in 1999 and 2000, [5][6][7][8] which confirmed earlier theoretical predictions, [9,10] has stimulated renewed interest in designing new tetracoordinate [11,12] and even hypercoordinate planar carbon molecules. [13][14][15][16] Notably, a series of hypercoordinate planar carbon species with boron ligands have been proposed. [13-15, 16a,c,e] Although none of these species is the global minimum on the potentialenergy surfaces, it has been suggested that they may be viable experimentally. The two proposed hexa-and heptacoordinate carbon species are D 6h CB 6 2À [13a,b,d, 14c, 15] and D 7h CB 7 À , [13b, 14c] respectively. The CB 7 À species is isoelectronic to B 8 2À , which we have shown previously to have a global-minimum D 7h structure with a heptacoordinate boron atom. [17][18][19][20] The D 7h CB 7 À can be viewed as replacing the central B À ion in B 82À by a C atom. Herein we report serendipitous experimental observation of CB 7 À . It was investigated by photoelectron spectroscopy (PES) and ab initio calculations, which showed that the observed species is a C 2v CB 7 À ion in which the C atom replaces a B À ion at the rim of the D 7h B 8 2À molecular wheel.The experiment was performed with a laser-vaporization cluster source and a magnetic-bottle photoelectron spectrometer (see Experimental Section).[21] We recently modified our cluster source by adding a 10-cm-long and 0.3-cm-diameter stainless steel tube to enhance cluster cooling.[22] We were using boron clusters, which we have previously investigated extensively, [17][18][19][20][23][24][25][26][27][28] to test the new cluster-source conditions. A 10 B-enriched disk target containing a small amount of Au was used as the laser-vaporization target.[23] Under certain conditions, when the vaporization laser was not perfectly aligned, we noted that in addition to the pure boron clusters we were also able to produce clusters containing one or two carbon atoms, as shown in Figure 1. The carbon most likely originated from impingement of the slightly misaligned vaporization laser beam on the stainless steel tubing. The trace amount of carbon contamination was ideal to produce boron clusters doped with only one or two carbon atoms, and the beam condition was stable and reproducible.The peak of the CB 7 À cluster is particularly intense with abundance as strong as those of the nearby pure B x À clusters (Figure 1). Its photoelectron spectra at two detachment laser wavelengths are shown in Figure 2. The 193-nm spectrum rev...

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Section: Comparison Of the Experimental Vdes Of Cb7− To The Calculatementioning

confidence: 99%

CB₇⁻: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon

et al. 2007

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“…The location of lowest‐energy structure of a cluster is very crucial in the cluster study. In current work, both randomized algorithms and exhaustive search method are used to search possible planar isomers of C n B 5 ( n = 1–7) clusters as the lowest‐energy isomers of most small boron–carbon clusters have planar geometries. At first, preliminary optimization for possible planar isomers of C n B 5 is carried out at B3LYP/6‐31G(d) level.…”

Section: Computational Detailsmentioning

confidence: 99%

“…On the other hand, many theoretical investigations about boron–carbon mixed clusters have been reported in recent years. For example, the boron–carbon clusters with hypercoordinated carbon or boron atom have been studied using different theoretical methods, which revealed that the aromaticity and stability of these clusters are related to the hypercoordinated atom . The global minima of CB 6 2− , CB 6 − , and C 2 B 5 − were searched using the genetic algorithm program GEGA and the bonding natures were analyzed by adaptive natural density partitioning (AdNDP) method to understand why the structures with a hexacoordinate carbon for CB 6 2− , CB 6 − , and C 2 B 5 − are higher in energy than the corresponding global minima .…”

Section: Introductionmentioning

confidence: 99%

Exploration on the structure, stability, and isomerization of planar C_n B₅ (n = 1−7) clusters

Wang

Cui

Shao

et al. 2013

Int. J. Quantum Chem.

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The structures, stabilities, nature of bonding, and potential energy surfaces of low-energy isomers of planar C n B 5 (n 5 127) have been systematically explored at the CCSD(T)/6-3111G(d)// B3LYP/6-3111G(d) level. Incremental binding energy (IBE) and second order energy difference (D 2 E) analyses demonstrate that C n B 5 clusters with even n have relatively higher stability. The nature of bonding in these clusters is discussed based on valence molecular orbital (VMO), and Mayer bond order (MBO). H€ uckel (4n 1 2) rule and nucleus-independent chemical shift (NICS) values suggest that the ground states of C 3 B 5 , C 4 B 5 , and C 7 B 5 have p aromaticity. VMO, electron localization function (ELF), adaptive natural density partitioning (AdNDP), and NICS analyses reveal the double aromaticity of C 3 B 5 cation. CB 5 and C 3 B 5 are stable both thermodynamically and kinetically based on isomerization analysis. In addition, the simulated IR spectra are expected to be helpful for future experimental studies of these clusters.

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“…Since then, the research in both directions has been intensively developed and extended to other main group element compounds with unusual coordination and/or configuration of their bonds [4][5][6][7][8][9][10][11]. Apart from protonated methanes in which the coordination number of carbon has been shown to be increased up to seven [9], a variety of new rather unusual structures with planar penta- [12,13], hexa- [14,15], hepta- [16], and octacoordinate [17] carbon and heptacoordinate nitrogen [18], hepta-and octacoordinate boron [19], silicon [17], and phosphorus [17] have been computationally discovered. A representative recent example is the carborane sandwich systems 1-3, in which the central carbon forms multicenter bonds with up to 12 neighboring ligands, as in 3 [20].…”

Section: Introductionmentioning

confidence: 99%

Sandwich compounds with central hypercoordinate carbon, nitrogen, and oxygen: A quantum‐chemical study

Minyaev

Gribanova

Starikov

2006

Heteroatom Chemistry

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Cited by 50 publications

References 7 publications

CB₇⁻: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon

CB₇⁻: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon

Exploration on the structure, stability, and isomerization of planar C_n B₅ (n = 1−7) clusters

Sandwich compounds with central hypercoordinate carbon, nitrogen, and oxygen: A quantum‐chemical study

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Untitled

Cited by 50 publications

References 7 publications

CB7−: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon

CB7−: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon

Exploration on the structure, stability, and isomerization of planar C n B5 (n = 1−7) clusters

Sandwich compounds with central hypercoordinate carbon, nitrogen, and oxygen: A quantum‐chemical study

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Product

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CB₇⁻: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon

CB₇⁻: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon

Exploration on the structure, stability, and isomerization of planar C_n B₅ (n = 1−7) clusters