Two-dimensional coordination compounds based on Fe(II) and Co(III) hexacyanometallates with Cu(II)(dien) groups: structures and magnetic properties

Keene, Tony D., Komm, Theresa, Hauser, Jürg and Krämer, Karl W. (2011) Two-dimensional coordination compounds based on Fe(II) and Co(III) hexacyanometallates with Cu(II)(dien) groups: structures and magnetic properties. Inorganica Chimica Acta, 373 (1), 100-106. (doi:10.1016/j.ica.2011.03.067).

Abstract

The crystal structures of two copper(II)(dien) coordination compounds with diamagnetic [Fe(II)(CN)(6)](4) or [Co(III)(CN)(6)](3) bridges were determined from single crystal X-ray diffraction and their magnetic properties investigated by SQUID measurements. The first, {[Cu(dien)](2)[Fe(CN)(6)]}(n)center dot 4n H2O (1), where dien is diethylenetriamine, consists of linear Cu(II)-Fe(II)-Cu(II) trimers. The Cu2+ ions are equatorially coordinated by dien and bridged by a hexacyanoferrate anion. A two-dimensional network is formed through longer axial Cu center dot center dot center dot NC-Fe bonds. The second, {{[(Cu(dien))(2)(pz)](2)[Co(CN)(6)]}[Co(CN)(6)]}(n)center dot 6n H2O (2), where pz is pyrazolate, contains butterfly-shaped Cu(II)(2)-Co(III)-Cu(II)(2) pentamers. The Cu2+ ions are again equatorially coordinated by dien and bridged by pz to form a dimer. Two dimers are linked through a [Co(III)(CN)(6)](3) anion to pentanuclear clusters, which are further connected into a layer via the second site of [Co(III)(CN)(6)](3) anions. Cu2+ has distorted square-pyramidal and octahedral coordination for 1 and 2, respectively, with elongated axial ligand distances due to the Jahn-Teller effect. The magnetic behavior of both compounds is consistent with Cu2+ S = 1/2 dimers, although with different bridging groups to give g = 2.157(2) and 2J/k(B) = -1.14(1) K for 1 and g = 2.15(1) and 2J/k(B) = -37.5(2) K for 2.

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Contributors

Author: Tony D. Keene

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