Syntheses of several kinds of one-dimensional nickel(II)-nitrito complexes: a new μ-nitrito nickel(II) alternating chain

Three new one-dimensional µ-nitrito nickel(II) complexes of formula [{NiL 1 (µ-NO 2 )} n ] [ClO 4 ] n 1, [{NiL 2 (µ-NO 2 )} n ] [ClO 4 ] n 2 and [{NiL 3 (µ-NO 2 )} n ] [ClO 4 ] n 3 have been synthesized and characterized [L 1 = N,N′-bis(2-amino ethyl)propane-1,3-diamine, L 2 = N,N′-bis(3-aminop ropyl)ethane-1,2-diamine, L 3 = N,N′-bis(3-aminop ropyl)propane-1,3-diamine]. Complex 3 crystallizes in the triclinic system, space group P, with a = 10.747(3), b = 9.413(2), c = 8.789(2) Å, α = 95.52(2), β = 108.98(3), γ = 106.83(3)°, Z = 2, R = 0.058. The nickel atom is placed in an octahedral environment with the µ-nitrito groups in trans position co-ordinated by the nitrogen atom and to the neighbouring nickel by one of its oxygen atoms. Inversion centres on the nitrito bridges but not on the nickel atoms allow an alternating system, whereas compounds 1 and 2 appear to be homogeneous one-dimensional chains. The three compounds show antiferromagnetic behaviour, with very similar J values of -27.4 cm -1 for 1, -32.3 cm -1 for 2 and -31.8 cm -1 for 3. Magnetic properties have been rationalized by means of extended-Hückel molecular orbital calculations.