A Novel Oxo-Centred,Trinuclear Iron Nicotinato Complex: Fe 3 (O)(C 6 NO 2 H 5 ) 6 (H 2 O) 3 ·3H 2 O·7Cl

Hydrothermal reaction of FeCl₃ and nicotinic acid gave a novel, trinuclear metal-nicotinato complex Fe₃(O)(C₆NO₂H₅)₆(H₂O)₃·3H₂O·7Cl. An X-ray crystal structure analysis reveals that it features an isolated structure. The crystal belongs to the rhombohedral, space group R--3c with a = b = 19.9410(6) Å, c = 30.505(1) Å, V = 10504.9(6) ų, Z = 6, C₃₆H₄₂Cl₇Fe₃N₆O₁₉, M_r = 1278.46, D_c = 1.213 g cm⁻³, S = 0.980, μ(MoKα) = 0.936 mm⁻¹, F(000) = 3894, R = 0.0694 and wR² = 0.1579. The iron atom has a slightly distorted octahedral geometry, coordinated by six oxygen atoms. All three octahedrons interconnect to each other via corner-sharing an oxygen atom, yielding an oxo-centred, trinuclear iron cluster. The [Fe₃(O)(C₆NO₂H₅)₆(H₂O)₃]⁷⁺ species, lattice water molecules and chloride ions are held together via hydrogen bonds to construct a three-dimensional (3-D) open framework, with a large void space (2803.9 ų) corresponding to 26.7% of the unit-cell volume (10504.9 ų).