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Synthesis of Secondary, Tertiary and Quaternary 1,3,5‐Triazapenta‐1,3‐dienes and Their Co II , Zn II , Pd II , Cu II and BF 2 Coordination Compounds
Author(s) -
Häger Ina,
Fröhlich Roland,
Würthwein ErnstUlrich
Publication year - 2009
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900042
Subject(s) - chemistry , deprotonation , protonation , medicinal chemistry , boron trifluoride , ligand (biochemistry) , tetrahydrofuran , diethyl ether , stereochemistry , organic chemistry , solvent , catalysis , ion , biochemistry , receptor
The secondary and tertiary 1,3,5‐triazapenta‐1,3‐dienes 2 and 3 are easily obtained by the reaction of N ‐imidoyl chlorides with amidines or from ethyl N ‐imidoylimidoates 5 and primary amines. In a new synthetic pathway the compounds 5 were prepared by the reaction of imidoates in their protonated or free form with N ‐imidoyl chlorides. A quaternary 1,3,5‐triazapenta‐1,3‐diene 4a is obtained by the reaction of the imidoate 5b with pyrrolidine. X‐ray diffraction studies of the tertiary 1,3,5‐triazapenta‐1,3‐diene 3c and its protonated form 3c·HCl allow the comparison of different patterns of intermolecular hydrogen bonding in the solid state. Two equivalents of a secondary 1,3,5‐triazapenta‐1,3‐diene 2 were treated at room temperature after deprotonation with potassium tert ‐butoxide with CuCl 2 , Ni(ClO 4 ) 2 or with Pd(ac) 2 (without deprotonation) to give the corresponding neutral 2:1 chelate complexes (2a) 2 ·Cu , (2a) 2 ·Ni and (2b) 2 ·Pd , respectively. A fluorescent boron complex 2b·BF 2 was obtained by reacting 2b with boron trifluoride–diethyl ether. From the tertiary triazapentadiene 3c and CoCl 2 or ZnCl 2 the six‐membered 1:1 chelate complexes 3c·CoCl 2 and 3c·ZnCl 2 , respectively, were obtained. In these cases a proton shift from the terminal nitrogen atom of the free ligand to the central nitrogen atom of the complex was observed. Two equivalents of 3c reacted at room temperature with Cu(ac) 2 or Pd(ac) 2 to form the neutral 2:1 chelate complexes (3c) 2 ·Cu and (3c) 2 ·Pd , respectively. A fluorescent 1:1 boron complex 3c·BF 2 was obtained from 3c and boron trifluoride–diethyl ether. In all cases the triazapentadienes act as neutral or anionic bidentate ligands to form six‐membered chelates with the metal ion or the boron centre. Most of the complexes were completely characterized, which included X‐ray crystallography.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)