Details

Autor(en) / Beteiligte

• Batten, Stuart R
• Murray, Keith S

Titel

Structure and magnetism of coordination polymers containing dicyanamide and tricyanomethanide

Ist Teil von

• Coordination chemistry reviews, 2003-11, Vol.246 (1), p.103-130

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2003

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Coordination polymers containing dicyanamide (N(CN) 2 −, dca) or tricyanomethanide (C(CN) 3 −, tcm) bridging ligands are described from the perspective of their structure and magnetism. The binary compounds α-M(dca) 2 form an isostructural series (M=Cr, Mn, Fe, Co, Ni, Cu) having a single rutile-like network that involves μ 1,3,5-dca bridging. They display quite diverse types of long-range magnetic order viz. canted-spin antiferromagnets (Cr, Mn, Fe), ferromagnets (Co, Ni, Cu). An up-to-date review is given of the diverse range of physical measurements made on the α-M(dca) 2 series together with interpretations for the different net exchange coupling and consequent 3D order. The doubly interpenetrating rutile network M(tcm) 2 series generally do not show long-range order except for a few members at very low temperatures. The ‘mixed’ self-penetrating network compounds M(dca)(tcm) do show long-range order (M=Co, Ni), albeit at lower T c values than for the M(dca) 2 parents. Modification of the M–dca networks is possible by incorporation of coligands into the structures. Ternary species of type M(dca) 2(L) n , where L is a terminal (e.g. pyridine, MeOH) or a bridging (e.g. pyrazine, 4,4′-bipyridine) coligand, display a diverse range of 1D, 2D and 3D structural types. With a few exceptions, the large number of compounds structurally characterised contain μ 1,5-dca bridging and display very weak antiferromagnetic coupling ( J<ca. −1 cm −1), typical of this bridging mode. Compounds such as Mn(dca) 2(pyrazine) display a magnetic phase transition at low temperatures. This is also the case in the isostructural 2D layer compounds M(dca) 2(H 2O) · phenazine (M=Fe, Ni) which, perhaps not surprisingly, do not have coordinated phenazines but, rather, phenazines intercalated between layers of M(dca) 2(H 2O) in which μ 1,3,5 and μ 1,5-dca bridging exists. Anionic networks of types M(dca) 3 − and M(dca) 4 2− formed by templation around cations of the organic (e.g. Ph 4E +, R 4N +) or inorganic (M(2,2′-bipyridine) 3 2+) types are described. The latter display no magnetic interactions between the weakly antiferromagnetically coupled anionic sub-lattice and the paramagnetic cationic sub-lattice.