| Autor: |
Jim-Min Fang, You Song, Gene-Hsiang Lee, Chih-Hsien Chien, Shie-Ming Peng, Chen-Yu Yeh, Jung-Che Chang |
| Rok vydání: |
2006 |
| Předmět: |
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| Zdroj: |
Dalton transactions (Cambridge, England : 2003). (26) |
| ISSN: |
1477-9226 |
| Popis: |
The preparation, crystal structures, magnetic properties and electrochemistry of novel linear hexanuclear nickel string complexes (Ni6(12+)) and their corresponding 1-e(-) reduction products (Ni6(11+)) are reported. In these complexes, the hexanickel chain is in a symmetrical arrangement (approximately D(4) symmetry) and is helically supported by four bpyany(2-) ligands [bpyany(2-) = the dianion of 2,7-bis(alpha-pyridylamino)-1,8-naphthyridine]. The Ni6(12+) complexes show that the two terminal nickel ions have high-spin states (S = 1) and the four inner ones have low-spin states (S = 0). The two terminal nickel ions exhibit weak antiferromagnetic coupling of ca.-5 cm(-1). All of Ni6(12+) complexes display three reversible redox couples at about -0.70, -0.20 and +1.10 V (vs. Ag/AgCl). The first reduction wave at about -0.20 V suggests facility of 1-e(-) reduction for the Ni(6)(12+) compounds. The reaction of Ni(6)(12+) complexes with hydrazine afforded the 1-e(-) reduction products (Ni6(11+)). As far as we are aware, the shortest bond distance of 2.202 A with a partial metal-metal bond was observed in Ni6(11+) compounds. The magnetic results of these Ni6(11+) compounds are in agreement with a localized model, in which the two terminal nickel ions are in a spin state of S = 1 whereas the central Ni3-Ni4 pair in a spin state of S = 1/2. The N6(11+) compounds show relatively strong antiferromagnetic coupling of about 60 cm(-1) between the terminal and the central dinickel ions. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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