Syntheses, structures and magnetism of linear tri- and tetra-copper chains containing anions of N, N′-bis(pyrimidine-2-yl)formamidine

Zhi Kai Chan, Chia Her Lin, Chih Chieh Wang, Jhy Der Chen*, Ju Chun Wang, C. W. Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Reaction of Kpmf (pmf = anion of N, N′-bis(pyrimidyl-2-yl)formamidine, Hpmf) with divalent copper salt CuX2 afforded the linear trinuclear complexes of the type [Cu3(pmf)4](X)2 (X = BF4, 1; NO3, 2; ClO4, 3), while reaction of Kpmf with monovalent copper salt CuX gave the linear tetranuclear complexes of the type Cu4(pmf)4X2 (X = Cl, 4; Br, 5). The copper atoms of complexes 1–5 are helically bridged by four pmf ligands, resulting in three different coordination modes for the pmf ligands. In complexes 1–3, one pmf ligand adopts a new coordination mode with the two amine nitrogen atoms chelating to the central copper atom, while the other three feature chelation by one pyrimidyl and one adjacent amine nitrogen atoms. The Cu(ii)⋯Cu(ii) distances are 2.729(2) and 2.825(2) Å for 1, 2.762(1) and 2.832(1) Å for 2 and 2.732(1) and 2.827(1) Å for 3. In complexes 4 and 5, the pmf ligands are coordinated to the copper atoms in tetradentate fashion with each nitrogen atom coordinating to one Cu atom. The Cu⋯Cu distances are 2.580(1) and 2.549(1) Å for 4 and 2.582(1) and 2.561(1) Å for 5. Antiferromagnetic interactions between the copper ions are observed with calculated g and J values of 2.03(1) and −188(2) cm−1 for 1, 2.09(1) and −268(3) cm−1 for 2, and 2.09(1) and −486(2) cm−1 for 5. By comparing the magnetic data it can be shown that the bonding mode of the pmf ligand is one of the important factors in determining the strengths of the Cu⋯Cu interactions in linear trinuclear and tetranuclear copper complexes.

Original languageEnglish
Pages (from-to)2183-2189
Number of pages7
JournalJournal of the Chemical Society. Dalton Transactions
Issue number16
DOIs
Publication statusPublished - 2008 Mar 6
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)

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