Nickel(II) complexes of the isomeric tetraazamacrocyclic ligands 1,11- and 1,8-bis(2-pyridylmethyl)-cyclam and of a structurally constrained N⁴,N⁸-methylene bridged

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• 作者：Batsanov ; Andrei S. ; Goeta ; André ; s E. ; Howard ; Judith A.K. ; Maffeo ; Davide ; Puschmann ; Horst ; et. al.
• 关键词：Crystal structure ; Tetraazamacrocycle ; Cyclam ; Nickel(II) complex ; Electrochemistry ; UV&ndash ; Visible spectroscopy
• 刊名：Polyhedron
• 出版年：2001
• 出版时间：April 30, 2001
• 年：2001
• 卷：20
• 期：9-10
• 页码：981-986
• 全文大小：126 K

文摘

The nickel(II) complexes of 1,8-bis(2′-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (L¹) and of the isomeric ligand 1,11-bis(2′-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (L²) have been isolated. The X-ray crystal structure of a mixed acetate/chloride salt of [NiL¹]²⁺ revealed an octahedral Ni coordination by two N atoms of the pyridine groups (in cis-related positions) and four of the macrocycle, which is folded along the 1,8-direction and bound in the cis-V configuration. The results of UV–Visible absorption spectroscopy and cyclic voltammetry in solution and the effective magnetic moments in the solid state are also consistent with octahedral N₆-coordination of high-spin nickel(II). The intermediate in the synthesis of ligand L², a bis-(2-pyridylmethyl) substituted formamidinium cation (L³)⁺, reacted with nickel(II) perchlorate to form a [Ni(H₂L³)Cl]²⁺ complex incorporating a methylene bridge between the non-pyridylmethylated N atoms (N⁴ and N⁸) of the macrocycle, which was characterised by X-ray crystallography. The Ni atom has a fac-octahedral coordination by the two pyridine and three macrocyclic nitrogens (the fourth one, N⁴, is protonated) and one Cl atom.