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Unsaturated Hetero Chains, V Synthesis, Structure, and Reactivity of Alkoxy‐substituted 2,4‐diazapentadienylium‐, 2,4,6‐Triazaheptatrienylium‐, and 2,4,6,8‐Tetraazanonatetraenylium Salts
Author(s) -
Schulte Norbert,
Fröhlich Roland,
Hecht Jürgen,
Würthwein ErnstUlrich
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619960312
Subject(s) - oxonium ion , chemistry , salt (chemistry) , alkoxy group , crystallography , condensation , alkylation , sodium salt , stereochemistry , reactivity (psychology) , ion , alkyl , organic chemistry , inorganic chemistry , medicine , physics , alternative medicine , pathology , thermodynamics , catalysis
Abstract The 1‐mono‐ and 1,ω‐dialkoxy‐substituted 2,4‐diazapentadienylium, and 2,4,6,8‐tetraazanonatetraenylium salts 3, 5 , and 10 were synthesized by oxonium salt alkylation of the corresponding 1‐oxa‐3,5‐diazahexatrienes 1 , of the 1‐oxa‐3,5,7‐triazaoctatetraenes 4 , and of the 1‐oxa‐3,5,7,9‐tetraazadecapentaenes 7 . The salts 3 and 10 are sufficiently stable to facilitate their isolation whereas salt 5 decomposes readily. For the synthesis of the alkoxysubstituted 1‐oxa‐3,5,7,9‐tetraazadecapentaenes 7 a new general pathway was developed, which involves the condensation of the salts 3 with the N ‐acylamidines 6 . The structural properties in the crystalline state were determined for the salts 3d and 10a as well as for the neutral compound 7a by X‐ray crystallography. All three compounds are characterized by non‐planar helical chains, much in contrast to their planar all‐carbon analogous polyenes and polymethinium salts. From the UV/Vis spectra we deduce that these compounds prefer non‐planar structures also in solution. All stable compounds were completely characterized by analytical and spectroscopic methods.