title: New versatile ligand family, pyrazine-modulated oligo-alpha-pyridylamino ligands, from coordination polymer to extended metal atom chains.
abstract: Here we designed and synthesized a new ligand, di(2-pyrazyl)amine (Hdpza) (1) and studied its coordination modes and the corresponding complexes with Cu(II), Co(II), Ni(II) and Cr(II). Hdpza is an analogue of the well-studied di(2-pyridyl)amine (Hdpa) ligand, which was used to generate the first extended metal atom chain. Three types of coordination modes were found: anti-anti style which resulted in a mononuclear compound [Cu(Hdpza)(2)(H(2)O)(2)](ClO(4))(2) (2); anti-syn which was observed in a complex for the first time and resulted in a 2-D coordination polymer [Co(mu(2)-Hdpza)(2)(NCS)(2)] (3); and syn-syn type which was observed in extended metal atom chains [Ni(3)(mu(3)-dpza)(4)Cl(2)] (4), [Ni(3)(mu(3)-dpza)(4)(NCS)(2)] (5) and [Cr(3)(mu(3)-dpza)(4)Cl(2)] (6). Weak antiferromagnetic coupling via Hdpza was observed in 3, whereas magnetic studies on extended metal atom chains 4 and 5 revealed that the interaction parameter was more than -200 cm(-1). Electrochemistry showed that the extended metal atom chains 4-6 are much more stable to oxidation than the Hdpa complexes, and are able to undergo reduction.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Rayyat Huseyn
authors.initials: RH
authors.lastname: Ismayilov
authors.forename: Wen-Zhen
authors.initials: WZ
authors.lastname: Wang
authors.forename: Gene-Hsiang
authors.initials: GH
authors.lastname: Lee
authors.forename: Rui-Ren
authors.initials: RR
authors.lastname: Wang
authors.forename: Isiah Po-Chun
authors.initials: IP
authors.lastname: Liu
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Yeh
authors.forename: Shie-Ming
authors.initials: SM
authors.lastname: Peng