METALLOSUPRAMOLECULAR COMPLEXES CONTAINING FERROCENYL GROUPS AS REDOX SPECTATORS - SYNTHESIS AND COORDINATION BEHAVIOR OF THE HELICAND 4',4'''-BIS(FERROCENYL)-2,2' - 6',2'',6'',2''',6''',2''''-QUINQUEPYRIDINE

The compound 4',4'''-bis(ferrocenyl)-2,2':6',2'':6'',2''':6''',2''''-quinquepyridine (L) has been prepared in two steps from ferrocenecarbaldehyde and 2,6-diacetylpyridine and its co-ordination behaviour investigated. Reaction with cobalt(II) and iron(II) salts gives the seven-co-ordinate complexes [ML(H2O)2][PF6]2 (M = Co or Fe). The presence of ferrocenyl groups in the ligand appears not to present a steric barrier to the formation of helicates, and the double-helical complexes [Ni2L2(H2O)2][PF6]4 and [Cu2L2][PF6]3 can be obtained by reaction with nickel(II) and copper(II) salts respectively. The compound L reacts with [RuCl3L'] (L' = 2,2': 6',2''-terpyridine or its 4'-dimethylamino, -methylsulfonyl or -ferrocenyl derivatives) to give the heteroleptic ruthenium(II) complexes [RuL(L')][PF6]2. In these complexes L is acting as a tridentate hypodentate ligand leaving a non-co-ordinated didentate 2,2'-bipyridyl moiety. The latter may act as a didentate domain for an additional ruthenium centre, and the tetranuclear complexes [L'RuLRuCl(L')][PF6]3 with two ruthenium(II) centres in two different, N2 and N5Cl, donor environments have been prepared.