Heterocyclic amine directed synthesis of metal(II)-oxalates: investigating the magnetic properties of two complete series of chains with S = 5/2 to S = 1/2

We report here two series of coordination polymer chains: the first being [M(II)(ox)(bnz)2]n (M = Mn 1, Fe 2, Co 3, Ni 4, Cu 5 and Zn 6; ox = oxalate C2O42−; bnz = benzimidazole) and the second [M(II)(ox)(btz)2]n (M = Mn 7, Fe 8, Co 9, Ni 10, Cu 11 and Zn 12; btz = benzotriazole). The first series displays an unusual homometallic [–Mi–Mii–Mii–]n chain topology and the second series is isostructural to [Fe(II)(ox)(btz)2]n, originally reported by Jia et al. (Collect. Czech. Chem. Commun., 2002, 67, 1609–1615). These two series allow us to make comparisons between the spin state of each metal and the magnetic coupling interaction within an isostructural series spanning the full range of spin states available in 3d metals and to investigate which models are the best to use in each case. Compound 8 is a single-chain magnet, the behaviour through spin-canting arising from a Dzyaloshinskii-Moriya interaction. Additionally, we have synthesised a two-dimensional coordination polymer {[Zn(II)(bnz)4][Zn(II)2(ox)3]}n (13), in which distorted hexagonal [Zn(II)2(ox)3]n2n− layers are hydrogen bonded by [Zn(II)(bnz)4]2+ cations to give an interlayer separation of 12.001(2) A.