title: Metal complexes of bridging neutral radical ligands: pymDTDA and pymDSDA.
abstract: Metal complexes of the 4-(2'-pyrimidyl)-1,2,3,5-dithiadiazolyl (pymDTDA) neutral radical ligand and its selenium analogue (pymDSDA) are presented. The following series of metal ions has been studied using M(hfac)(2) as the coordination fragment of choice (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato): Mn(II), Co(II), Ni(II), and Zn(II). The binuclear cobalt and nickel complexes of pymDTDA both exhibit ferromagnetic (FM) coupling between the unpaired electrons on the ligand and the metal ion, while the binuclear zinc complex of pymDTDA is presented as a comparative example incorporating a diamagnetic metal ion. The binuclear manganese complex of pymDTDA, reported in a preliminary communication, is compared to the pymDSDA analogue, and new insight into the magnetic behavior reveals that intermolecular magnetic coupling, mediated by chalcogen-oxygen contacts, gives rise to a significant increase in the χT product at low temperature. Surprisingly, the binuclear nickel complex of pymDSDA forms dimers in the solid state, as do the mononuclear complexes of cobalt and nickel with pymDTDA. In addition, mixed mononuclear/binuclear complexes of Mn- and Zn(pymDTDA) have been identified.
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: MacDonald
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Clérac
authors.forename: Ie-Rang
authors.initials: IeR
authors.lastname: Jeon
authors.forename: Michael
authors.initials: M
authors.lastname: Jennings
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Lough
authors.forename: James
authors.initials: J
authors.lastname: Britten
authors.forename: Craig
authors.initials: C
authors.lastname: Robertson
authors.forename: Paul A
authors.initials: PA
authors.lastname: Dube
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Preuss