SYNTHESIS AND STRUCTURAL, SPECTROSCOPIC AND MAGNETIC CHARACTERIZATIONOF IRON(II) AND IRON(III) COMPLEXES OF N-2-PYRIDINYLCARBONYL-2-PYRIDINECARBOXIMIDATE

One iron(II) complex of N-2-pyridinylcarbonyl-2-pyridinecarboximidate monoanion (bpca), [Fe(bpca)2] . H2O (1), and three iron(III) complexes , [Fe(bpca)Cl2(H2O)] . (CH3)2CO (2), [Fe(bpca)2](NO3) . 1.67H2O (3), [ Fe(bpca)2](ClO4) (4), have been prepared and characterized by means of IR, UV-Vis and EPR spectroscopy and magnetic susceptibility measureme nts, where appropriate. The crystal structures of 1-3 have been determ ined from single crystal X-ray data, showing that the metallic ions ar e surrounded in all cases by distorted octahedral coordination spheres . From magnetic measurements it is evident that compounds 1 and 3 are practically in the low-spin state at room temperature, compound 2 is i n the high-spin state in all the range of measured temperatures and co mpound 4 shows spin-crossover behaviour. Crystal data for 1: space gro up P2(1)/c, a = 8.827(1), b = 8.941(2), c = 28.957(4) angstrom, beta = 95.90(1)-degrees, Z = 4; for 2: space group P2(1)/c, a = 8.293(2), b = 13.779(2), c = 15.884(4) angstrom, beta = 98.22(1)-degrees, Z = 4; f or 3: space group P1BAR, a = 8.840(1), b = 10.713(1), c = 14.989(1) an gstrom, alpha = 71.16(1), beta = 73.43(1), gamma = 82.67(1)-degrees, Z = 2.