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Wechselwirkungen in Kristallen, 176. Mitteilung , Redox‐Reaktionen von Hexahydropyren: Kristallstrukturen seiner Radikalanion‐Salze sowie von Trihydropyrenylium‐tetrachloroaluminat und Dichtefunktionaltheorie‐Berechnungen
Author(s) -
Bock Hans,
Claridge Rodney F.,
Bogdan Camelia,
Sievert Mark,
Krenzel Volker
Publication year - 2001
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20010613)84:6<1227::aid-hlca1227>3.0.co;2-c
Subject(s) - chemistry , delocalized electron , crystallography , radical ion , redox , dehydrogenation , reagent , oxidizing agent , bond length , crystal structure , natural bond orbital , ion , medicinal chemistry , computational chemistry , stereochemistry , density functional theory , inorganic chemistry , organic chemistry , catalysis
Redox Reactions of Hexahydropyrene: Crystal Structures of Its Radical‐Anion Salts as well as of Trihydropyrenylium Tetrachloroaluminate and Density‐Functional‐Theory Calculations Hexahydropyrene 1 , a doubly propane‐1,3‐diyl‐bridged peri ‐naphthalene derivative wtih 10 π ‐electrons allows both oxidation to its cation as well as reduction to its radical‐anion salts, which could be crystallized and structurally characterized – a rather rare case for small unsaturated hydrocarbons. The unexpected formally threefold dehydrogenation by the oxidizing system AlCl 3 /H 2 CCl 2 ( Bock 's reagent) generated the hitherto unknown 1,2,3‐trihydropyrene cation in two polymorphic crystals, which contain 12 π ‐electrons delocalized over three anellated six‐membered rings comprising 13 π ‐centers. Structural comparison of the altogether four crystallized redox products [K + solv ][M .− ] 2a , [K + solv ][M .− ] ∞ 2b , [Na + solv ][M .− ] 2c , and [(M−3 H) + ][AlCl − 4 ] 3 with the neutral hydrocarbon 1 reveals only small differences in bond lengths and angles, but establishes solvation contacts, π ( η 6 )⋅⋅⋅K + coordination in the polymer 2b , the flattening of one molecular half in the trihydropyren cation of 3 and ten H‐bonds CH⋅⋅⋅Cl to the AlCl 4 − counter anion of 3 . DFT/NBO Charge distributions, calculated based on the experimental structural parameters, show charge accumulation in the propanediyl bridges as well as in the peripheral naphthalene C−C bonds of the radical anions. The largest changes result expectedly for the formally triply dehydrogenated 1 , i.e. the trihydropyren cation of 3 , with two slightly positive and partly considerably less negative π ‐centers.