Polyhedral B9C2H11, B8C2H10, B7C2H9, and B6C2H8 carboranes and the B7C2H13 system

Tebbe, F. N.; Garrett, Philip M.; Hawthorne, M. Frederick

doi:10.1021/ja01006a007

Cited by 77 publications

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“…Ϫ has not been adequately characterised. 4 Since the protonation reactions introduce B-H-B bridges, and not C-H-B bridges, one argument against the existence of 7,9-C 2 B 9 H 13 is the lack of a B-B bond available on the open face to accommodate the second bridging hydrogen. 2 The 11-vertex closo-carborane, 2,3-C 2 B 9 H 11 , is formed in 36% yield by the elimination of hydrogen in the reaction of Cs(7,9-C 2 B 9 H 12 ) with polyphosphoric acid at elevated temperatures (Scheme 1).…”

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“…2 The 11-vertex closo-carborane, 2,3-C 2 B 9 H 11 , is formed in 36% yield by the elimination of hydrogen in the reaction of Cs(7,9-C 2 B 9 H 12 ) with polyphosphoric acid at elevated temperatures (Scheme 1). 4 High yields of the C-phenyl derivative 2-Ph-2,3-C 2 B 9 H 10 were obtained from Cs(7-Ph-7,9-C 2 B 9 H 11 ) by the same method. 4 Acidification of the 7,8-anions 7,8-R,RЈ-7,8-C 2 B 9 H 10 Ϫ results in protonation to generate neutral nidocarboranes 7,8-R,RЈ-7,8-C 2 B 9 H 11 , which undergo thermolysis at 100 ЊC to give C-substituted closo-carboranes 2,3-R,RЈ-2,3-C 2 B 9 H 9 .…”

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“…4 High yields of the C-phenyl derivative 2-Ph-2,3-C 2 B 9 H 10 were obtained from Cs(7-Ph-7,9-C 2 B 9 H 11 ) by the same method. 4 Acidification of the 7,8-anions 7,8-R,RЈ-7,8-C 2 B 9 H 10 Ϫ results in protonation to generate neutral nidocarboranes 7,8-R,RЈ-7,8-C 2 B 9 H 11 , which undergo thermolysis at 100 ЊC to give C-substituted closo-carboranes 2,3-R,RЈ-2,3-C 2 B 9 H 9 . 5- 7 Boron substituted 11-vertex closo-carboranes are limited to those containing hydroxyl and carboranyl groups.…”

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Cage-closing reactions of the nido-carborane anion 7,9-C2B9H12− and derivatives; formation of neutral 11-vertex carboranes by acidification

Fox

Hughes

Malget

2002

J. Chem. Soc., Dalton Trans.

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B 9 H 10 (X = Cl, I), are formed from reactions of salts containing 1(6)-X-7,9-C 2 B 9 H 11 Ϫ anions with H 2 SO 4 , and 4-F-2,3-( p-FC 6 H 4 ) 2 -2,3-C 2 B 9 H 8 is formed from (Bu 4 N)(3-F-7,9-( p-FC 6 H 4 ) 2 -7,9-C 2 B 9 H 9 ) and F 3 CSO 3 H. Elimination of the ethoxide and fluoride substituents from the cage occurs during acidification of salts containing 10-OEt-7,9-C 2 B 9 H 11 Ϫ and 10-F-7,9-( p-FC 6 H 4 ) 2 -7,9-C 2 B 9 H 9 Ϫ by F 3 CSO 3 H, resulting in the closo-carboranes 2,3-C 2 B 9 H 11 and 2,3-( p-FC 6 H 4 ) 2 -2,3-C 2 B 9 H 9 as major products respectively. A mixture of B-Me-2,3-C 2 B 9 H 10 isomers is obtained from salts containing the 8-Me-7,9-C 2 B 9 H 11 Ϫ and 10-Me-7,9-C 2 B 9 H 11 Ϫ anions with H 2 SO 4 . B-Me-2,3-C 2 B 9 H 10 is suggested to be fluxional in solution with 4-Me-2,3-C 2 B 9 H 10 as the major component. Protonation of the fluxional anion 10(11)-endo-Me-7,9-C 2 B 9 H 11 Ϫ with acetic acid gives a neutral nido-carborane 11-Me-2,8-C 2 B 9 H 12 rather than closo-B-Me-2,3-C 2 B 9 H 10 . Molecular geometries of 11-vertex closo-carboranes and B-methyl-nido-carboranes are determined by the combined ab initio/GIAO/NMR method at the GIAO-B3LYP/6-311G*//MP2/6-31G* level of theory. Scheme 1 The reactions of nido-7,9-C 2 B 9 H 12 Ϫ 1a and nido-7,8-C 2 B 9 H 12 Ϫ with acid and the synthesis of closo-2,3-C 2 B 9 H 11 2a showing the cage numbering. Exo-hydrogens are omitted for clarity. DALTON

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Cage-closing reactions of the nido-carborane anion 7,9-C2B9H12− and derivatives; formation of neutral 11-vertex carboranes by acidification

Fox

Hughes

Malget

2002

J. Chem. Soc., Dalton Trans.

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“…The reaction of the 11vertex closo-2,3-C 2 B 9 H 11 carborane and closo-1,8-C 2 B 9 H 11 with nitrogen-containing bases, such as pyridine or ethylamine, produced the corresponding charge-compensated 3-Me 3 N-nido-7,9-C 2 B 9 H 11 without cage degradation. 24,25 In our previous NMR studies with 1-(2-methylpyridyl)-2dicarba-closo-carborane, we observed that this functionalized carborane undergoes a cage-opening reaction in dimethylsulfoxide at room temperature. 26 This encouraged us to investigate the use of a chelating amine, such as 2-(aminomethyl)-pyridine, to effect a low-temperature cage degradation reaction of functionalized 1,2-C 2 B 10 H 10 R 2 (R = CH 2 OH) carboranes.…”

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confidence: 91%

Cage opening of 1,2‐(CH₂OH)₂‐closo‐1,2‐C₂B₁₀H₁₀ with 2‐(aminomethyl)‐pyridine: synthesis and structure of a cobalt salt of functionalized nido‐C₂B₉H₁₀ mono anion

Oki

Gilbes

Tarasyuk

et al. 2003

Applied Organom Chemis

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The reaction of 1,2-(CH 2 OH) 2 -closo-1,2-C 2 B 10 H 10 carborane with 2-(aminomethyl)-pyridine in methylene chloride at room temperature led to the partial cage degradation of the closo carborane and its conversion to the nido derivative. The addition of cobalt chloride hexahydrate in methanol to the mixture produced orange crystals 1. The crystal structure of the orange compound has been determined.

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“…Thus, thermal isomerization of C-methyl 52,59 , C-pentyl 58 , C-hexyl 58 , C-phenyl 52 , C-(C 6 H 4 -4-Br) (ref. 58 ), and C-(C 6 H 4 -4-F) (ref.…”

Section: Preparation Of the Parent Clustersmentioning

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Four Decades of Organic Chemistry of closo-Boranes: A Synthetic Toolbox for Constructing Liquid Crystal Materials. A Review

Kaszyński

1999

Collect. Czech. Chem. Commun.

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Introduction and transformations of organic functional groups to ten- and twelve-vertex closo-boranes and heteroboranes is reviewed in the context of preparation of liquid crystalline compounds. The review, containing 198 references, is designed as a synthetic manual for materials chemists and focuses on methods for engineering molecules with elongated shapes and variable dipole moments. Several underdeveloped aspects of closo-borane chemistry are identified.

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Polyhedral B9C2H11, B8C2H10, B7C2H9, and B6C2H8 carboranes and the B7C2H13 system

Cited by 77 publications

References 2 publications

Cage-closing reactions of the nido-carborane anion 7,9-C2B9H12− and derivatives; formation of neutral 11-vertex carboranes by acidification

Cage-closing reactions of the nido-carborane anion 7,9-C2B9H12− and derivatives; formation of neutral 11-vertex carboranes by acidification

Cage opening of 1,2‐(CH₂OH)₂‐closo‐1,2‐C₂B₁₀H₁₀ with 2‐(aminomethyl)‐pyridine: synthesis and structure of a cobalt salt of functionalized nido‐C₂B₉H₁₀ mono anion

Four Decades of Organic Chemistry of closo-Boranes: A Synthetic Toolbox for Constructing Liquid Crystal Materials. A Review

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Polyhedral B9C2H11, B8C2H10, B7C2H9, and B6C2H8 carboranes and the B7C2H13 system

Cited by 77 publications

References 2 publications

Cage-closing reactions of the nido-carborane anion 7,9-C2B9H12− and derivatives; formation of neutral 11-vertex carboranes by acidification

Cage-closing reactions of the nido-carborane anion 7,9-C2B9H12− and derivatives; formation of neutral 11-vertex carboranes by acidification

Cage opening of 1,2‐(CH2OH)2‐closo‐1,2‐C2B10H10 with 2‐(aminomethyl)‐pyridine: synthesis and structure of a cobalt salt of functionalized nido‐C2B9H10 mono anion

Four Decades of Organic Chemistry of closo-Boranes: A Synthetic Toolbox for Constructing Liquid Crystal Materials. A Review

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Cage opening of 1,2‐(CH₂OH)₂‐closo‐1,2‐C₂B₁₀H₁₀ with 2‐(aminomethyl)‐pyridine: synthesis and structure of a cobalt salt of functionalized nido‐C₂B₉H₁₀ mono anion