Oxonitrates VO(NO_3)_3 and MoO_2(NO_3)_2 and Nitronium and Nitrosonium Nitratometallates as Nitrating Agents

摘要

Dissolution of vanadium in anhydrous HNO_3 followed by exposure of the solution in a dessicator over P_2O_5 gave liquid vanadyl trinitrate (I). The X-ray diffraction analysis of I was carried out for a single crystal grown on cooling the liquid in a sealed capillary. The structure is composed of VO(NO)_3 molecules in which the V atom has an unusually high C.N. 7; it coordinates the terminal O atom and three bidentate nitrate groups to form a distorted pentagonal bipyramid as the coordination polyhedron with the terminal O atom occupying one axial vertex. Using the GAMESS program package, ab initio calculation of the structure of VO(NO_3)_3 in the liquid phase was carried out. It was shown that in all three physical states, vanadyl trinitrate retains its molecular structure almost invariable. Toluene and naphthalene nitration using I and (NO_2)[Fe(NO_3)_4], NO[Cu(NO_3)_3], (NO)_3/4(NO_2)i/4[Zr(NO_3)_5], and MoO_2(NO_3)_2 proceeds at high rates at low temperatures to give an unusually high para-nitrotoluene percentage in the products as compared with the ortho-isomer. The activity of the studied compounds in the nitration of naphthalene decreases in the series VO(NO_3)_3 > (NO)_(3/4)(NO_2)_(1/4)[Zr(NO_3)_5] > MoO_2(NO_3)_2.