Monohelical quinquepyridine complexes of rhenium-(I) and -(III)

Three 2,2':6',2 '':6 '',2''': 6''',2''''-quinquepyridine (qpy) complexes of rhenium, [Cl(OC)(3)Re-I(qpy)Re-I(CO)(3)Cl] 1, [(py)(OC)(3)Re-I(qpy)Re-I(CO)(3)(py)][ClO4](2) 2 (py = pyridine) and [Re-III(qpy)Cl-2][ClO4] 3, have been prepared and their physicochemical properties studied. The crystal structures of 2 and 3 have been determined: 2 is a monohelical bimetallic complex with two fac-tricarbonyl rhenium(I) moieties linked by the qpy ligand and;the five pyridyl rings of qpy divide in the fashion bipy-py-bipy (bipy = bipyridine fragment and py = pyridine spacer); 3 is a seven-co-ordinated monohelical rhenium(III) complex with pentagonal-bipyramidal geometry in which the two chloride ligands are trans to each other. Complexes land 2 display photoluminescence in the spectral range 560-600 nm. The electrochemical properties of 2 and 3 are discussed.