Issue 16, 2002
From the journal:

Journal of the Chemical Society, Dalton Transactions

Antiferromagnetic coupling of transition metal spins across pyrimidine and pyrazine bridges in dinuclear manganese(ii), cobalt(ii), nickel(ii) and copper(ii) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate complexes

Takayuki Ishida,*a   Takashi Kawakami,b   Shin-ichi Mitsubori,a   Takashi Nogami,a   Kizashi Yamaguchib  and  Hiizu Iwamurac  

* Corresponding authors

a Department of Applied Physics and Chemistry, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
E-mail: ishi@pc.uec.ac.jp

b Department of Chemistry, Graduate School of Science, Osaka University, Osaka 560-0043, Japan

c The University of the Air, Wakaba, Mihama-ku, Chiba 261-8586, Japan

Abstract

Dinuclear manganese(II), cobalt(II), nickel(II), and copper(II) complexes bridged by pyrimidine and pyrazine derivatives, L[M(hfac)2]2 [L = 4,6-di(2-pyridyl)pyrimidine (DPPM), 2,3-di(2-pyridyl)pyrazine (DPPZ); M = Mn, Co, Ni, Cu; hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate], were synthesized and their magnetic properties were studied. Antiferromagnetic couplings across the pyrimidine ring were observed for the DPPM complexes with the exchange parameters, 2J/kB, of −0.40, −3.1, −9.1 and −46 K for M = Mn, Co, Ni and Cu, respectively. The pyrimidine nitrogen atoms are coordinated at the axial position of each metal ion for M = Mn, Co and Ni, and coordinated equatorially for M = Cu. The DPPZ complexes also exhibited antiferromagnetic interactions, which are weaker than those of the DPPM complexes. Crystal structure analysis indicated that the molecular structures of the four DPPZ complexes are essentially the same in spite of various space groups. Ab initio unrestricted Hartree-Fock calculations on DPPM[Cu(hfac)2]2 predicting a positive effective exchange integral (J) are inconsistent with the experiments, because of overestimation of the role of π-type spin-polarization in DPPM. The J value from the density functional UB3LYP calculations is close to the experimentally determined value, which arises from a σ-type exchange pathway across the pyrimidine ring.

Graphical abstract: Antiferromagnetic coupling of transition metal spins across pyrimidine and pyrazine bridges in dinuclear manganese(ii), cobalt(ii), nickel(ii) and copper(ii) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate complexes

About
Cited by
Related
Download options Please wait...

Supplementary files

Article information

DOI
https://doi.org/10.1039/B202635J
Article type
Paper
Submitted
14 Mar 2002
Accepted
10 Jun 2002
First published
11 Jul 2002

J. Chem. Soc., Dalton Trans., 2002, 3177-3186

Permissions

Request permissions

Antiferromagnetic coupling of transition metal spins across pyrimidine and pyrazine bridges in dinuclear manganese(II), cobalt(II), nickel(II) and copper(II) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate complexes

T. Ishida, T. Kawakami, S. Mitsubori, T. Nogami, K. Yamaguchi and H. Iwamura, J. Chem. Soc., Dalton Trans., 2002, 3177 DOI: 10.1039/B202635J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements