Quantum Chemical Studies of Boron Fullerene Analogs

Derecskei‐Kovacs, Agnes; Dunlap, Brett I.; Lipscomb, W. N.; Lowrey, Alfred H.; Massa, Lou

doi:10.1021/ic00103a004

Cited by 23 publications

(20 citation statements)

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“…[10] Renewed interest in borazines can be associated with the preparation of BN-fibres and nanotubes [11][12][13][14] as precursors in the formation of BNC-and BSiN-type materials [15][16][17] as well as the challenge of preparing BN-"fullerenes". [18][19][20] These latter compounds will be built from edge-sharing [ ‡] Contribution to the Chemistry of Boron, 260. Part 259: Ref.…”

Section: Introductionmentioning

confidence: 99%

Structural Chemistry of Borazines

Anand¹,

Nöth²,

Schwenk‐Kircher³

et al. 2008

Eur J Inorg Chem

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Keywords: Borazines / Ring distortionThe solid-state structure of (HN=BF) 3 has been redetermined. It is characterised by a stacking of the molecules, similar to hexagonal boron nitride. In contrast, (F 3 CH 2 N=BF) 3 shows no intermolecular interactions between the planar borazine rings. In (Cl 2 BN=BCl) 3 , the Cl 2 B groups are almost perpendicularly oriented to the planar borazine ring and its B-Cl bonds are shorter than the Cl-B bonds to the ring boron atoms. Reactions of (Cl 2 BN=BCl) 3 with Me 3 SiNMe 2 allows a successive Cl/Me 2 N exchange. Depending on the molar ratio, the compounds [Cl

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Section: Introductionmentioning

confidence: 99%

Structural Chemistry of Borazines

Anand¹,

Nöth²,

Schwenk‐Kircher³

et al. 2008

Eur J Inorg Chem

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“…[1][2][3][4][5] Boron, with three valence electrons in 2s and 2p orbitals, can form sp 2 hybridized orbitals. The crystalline forms of boron contain B 12 icosahedral units, but the most stable structure of bulk boron is controversial.…”

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confidence: 99%

Boron fullerenes: FromB80to hole doped boron sheets

et al. 2009

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We demonstrate the existence of a family of stable boron fullerenes containing 80n 2 atoms that is related to the family of 60n 2 carbon icosahedral fullerene series and is compatible with the recently proposed stable boron sheets composed of triangular and hexagonal motifs. All electron density-functional calculations on the B 320 , B 720 , B 1280 , and B 2000 confirm their stability and show that the quantum size effects open up electronic band gaps in the boron fullerenes at B 1280 . Boron fullerenes below B 2000 have valence electronic structure identical to their corresponding carbon cousins from 60n 2 family.Since the discovery of carbon fullerenes and nanotubes, several studies have examined the possible existence of hollow cage structures for the neighboring element, boron. 1-5 Boron, with three valence electrons in 2s and 2p orbitals, can form sp 2 hybridized orbitals. The crystalline forms of boron contain B 12 icosahedral units, but the most stable structure of bulk boron is controversial. 6-8 In cluster form, for very small sizes containing up to 20 atoms, it prefers planar or quasiplanar structures. The planar to three-dimensional transition in boron clusters seems to occur around B 20 . 9,10 Around this size the double ring tubular structures are more favorable. The extended planar honeycomb sheet, i.e., graphene equivalent of boron, is electron deficient and unstable. 11,12 The addition of a boron atom at the center of each hexagon results in a triangular sheet which is electron rich. This sheet is compatible with Aufbau principle of Boustani, 4 which suggests that the most stable boron nanostructures would be based on buckled triangular motifs. 13 The flat triangular sheet buckles when optimized and is more stable than the planar honeycomb sheet. The nanotubes formed by curling up the buckled triangular sheets are metallic. 11 During the last year, a number of interesting works on boron nanostructures have been reported ͑cf. Fig. 1͒. [14][15][16][17][18][19][20] In the first of these, a stable hollow cage structure of 80 boron atoms was reported by Szwacki et al. 14 The most interesting aspect of the B 80 is its structural resemblance with C 60 fullerene. The basic framework of the B 80 fullerene is similar to that of C 60 with 12 pentagonal and 20 hexagonal rings ͑see Fig. 1͒. The B 60 , an exact analog of C 60 , is electron deficient and unstable. However, an addition of 20 boron atoms at the center of each hexagonal ring stabilizes the electron deficient B 60 to give the stable B 80 fullerene. The B 80 fullerene is isovalent ͑equal number of valence electrons͒ with C 60 . Szwacki et al. 14 explained the stability of B 80 fullerene in terms of its structure of six interwoven double rings.About the same time, Tang and Ismail-Beigi, 15 and Yang et al. 16 proposed novel boron sheets that consist of combinations of triangular and hexagonal rings ͑cf. Fig. 1͒. These boron sheets are obtained by removing atoms from flat triangular sheets and can be viewed as hole doped triangular sheets. This arrangem...

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“…According to thermodynamic stabilities, closo -borane dianions such as [B 17 H 17 ] 2− and [B 16 H 16 ] 2− should be even more stable than [B 12 H 12 ] 2− [ 128 ]. Indeed, DFT calculations predict that the formation of large clusters (such as [B 42 H 42 ] 2− , [B 60 H 60 ] 2− , [B 92 H 92 ] 2− ) is possible [ 129 , 130 , 131 , 132 ]. However, one should keep in mind that the more B–H bonds present in a polyhedral closo -borane, the higher its stability, since more energy is stored in these chemical bonds [ 50 ].…”

Section: Resultsmentioning

confidence: 99%

Thermodynamic Hydricity of Small Borane Clusters and Polyhedral closo-Boranes

et al. 2020

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Thermodynamic hydricity (HDAMeCN) determined as Gibbs free energy (ΔG°[H]−) of the H− detachment reaction in acetonitrile (MeCN) was assessed for 144 small borane clusters (up to 5 boron atoms), polyhedral closo-boranes dianions [BnHn]2−, and their lithium salts Li2[BnHn] (n = 5–17) by DFT method [M06/6-311++G(d,p)] taking into account non-specific solvent effect (SMD model). Thermodynamic hydricity values of diborane B2H6 (HDAMeCN = 82.1 kcal/mol) and its dianion [B2H6]2− (HDAMeCN = 40.9 kcal/mol for Li2[B2H6]) can be selected as border points for the range of borane clusters’ reactivity. Borane clusters with HDAMeCN below 41 kcal/mol are strong hydride donors capable of reducing CO2 (HDAMeCN = 44 kcal/mol for HCO2−), whereas those with HDAMeCN over 82 kcal/mol, predominately neutral boranes, are weak hydride donors and less prone to hydride transfer than to proton transfer (e.g., B2H6, B4H10, B5H11, etc.). The HDAMeCN values of closo-boranes are found to directly depend on the coordination number of the boron atom from which hydride detachment and stabilization of quasi-borinium cation takes place. In general, the larger the coordination number (CN) of a boron atom, the lower the value of HDAMeCN.

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Quantum Chemical Studies of Boron Fullerene Analogs

Cited by 23 publications

References 0 publications

Structural Chemistry of Borazines

Structural Chemistry of Borazines

Boron fullerenes: FromB80to hole doped boron sheets

Thermodynamic Hydricity of Small Borane Clusters and Polyhedral closo-Boranes

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