UNUSUAL NITRITE COMPLEXES OF IRON(III) AND IRON(II) STABILIZED BY THETRIS(3,5-DIMETHYLPYRAZOLYL)BORATE LIGAND

Halide metathesis with silver nitrite allows for either stepwise or co mplete substitution of all three chloride ligands in the iron(III) com pound [NEt4][HB(3,5-Me(2)pz)(3)FeCl3] (ii to give the complexes [NEt4] [HB(3,5-Me(2)pz)3(F)e(ONO)(x)Cl3-x], x = 1-3 (2-4), and [NEt4][HB(3,5- Me(2)pz)(3)Fe(eta(2)-ONO)Cl] (5), which were characterized by elementa l analyses, electrochemistry and IR, EPRI and UV-vis spectroscopy. Sin gle-crystal X-ray diffraction was used to characterize the ferric comp lexes 2 and 3 and the ferrous chelating nitrito complex, 5. The crysta l structures of the ferric complexes exhibit monodentate, O-bound nitr ito ligands, while the change in metal oxidation state from +3 to +2 l eads to a chelating nitrito ligand in 5.