title: Novel linear hexanuclear cobalt string complexes (Co6(12+)) and one-electron reduction products (Co6(11+)) supported by four bpyany2- ligands.
abstract: The new ligand, 2,7-bis(alpha-pyridylamino)-1,8-naphthyridine (H2bpyany), was synthesized by the reaction of 2,7-dichloro-1,8-naphthyridine with 2-aminopyridine in the presence of t-BuOK under palladium(0)-catalyzed conditions. The preparation and characterization of novel hexacobalt string complexes, [Co6(mu6-bpyany)4(NCS)2](PF6)n (n=1 (1); n=2 (2)) and [Co6(mu6-bpyany)4(OTf)2](OTf)n (n = 2 (3); n = 1 (4)) are presented. The crystal structures for compounds have been determined by X-ray crystallography. Compounds 1 and 4 have the Co6 11+ configurations and are air-stable. Compounds 2 and 3 with Co6 12+ configurations are structurally similar to 1 and 4, respectively. The electrochemistry of 1 displays four redox couples at E1/2= -0.55, +0.38, +0.91, and +1.18 V (vs. Ag/AgCl). The magnetic data show that compounds 1 and 4 are in a spin state of S = 1/2, and 2 and 3 in a spin state of S = 1. The results of the EHMO calculations on compounds 1 and 2 are in agreement with their magnetic measurements.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan.
authors.forename: Chih-Hsien
authors.initials: CH
authors.lastname: Chien
authors.forename: Jung-Che
authors.initials: JC
authors.lastname: Chang
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Yeh
authors.forename: Gene-Hsiang
authors.initials: GH
authors.lastname: Lee
authors.forename: Jim-Min
authors.initials: JM
authors.lastname: Fang
authors.forename: Shie-Ming
authors.initials: SM
authors.lastname: Peng