Ruthenium(II) complexes of novel 4′-ethoxy- and 4′-hydroxy-5,5"-dimethyl-2,2′:6′,2"-terpyridines:: X-ray crystal structures of 4′-ethoxy-5,5"-dimethyl-2,2":6′,2"-terpyridine and the ruthenium(II) complex of 4′-ethoxy-5,5"-dimethyl-2,2′:6′,2"-terpyridine with 4′-chloro-2,2′:6′,2"'-terpyridine

The key intermediates for the Krohnke methodology for the synthesis of oligopyridines, 4-functionalised-2,6-diacetylpyridines (4-substituent = Cl, OEt or benzyloxy) have been synthesised. 4-Ethoxy-2,6-diacetylpyridine was reacted to give novel 4'-ethoxy2.2':6',2 "-terpyridines which possess substituents at C(4), C(5) and/or C(6) of both terminal pyridines. By cleavage of the ethyl ether protecting group from 4'-ethoxy-5,5 "-dimethyl-2,2':6',2 "-terpyridine, 4'-hydroxy-5,5 "-dimethyl-2,2':6',2 "-terpyridine was obtained. Ruthenium(II) complexes were prepared by the reaction of the substituted terpyridine ligands with [(Cl-tpy)RuCl3] (4'-chloro-2,2':6',2 "-terpyridine) and their chemical and electrochemical properties have been investigated. The structures of 4'-ethoxy-5,5 "-dimethyl-2,2':6',2 "-terpyridine and the ruthenium(II) complex of 4'-ethoxy-5,5 "-dimethyl-2,2':6',2 "-terpyridine with 4'-chloro-2,2':6',2 " terpyridine have been determined by X-ray structure analysis. (C) 1999 Elsevier Science Ltd. All rights reserved.