名称:
Oxidation of coordinated ethylenediamine in platinum(IV) complexes with bromine. Crystal structures of [Pt(en)Py2Br2]Br2 · H2O, [Pt(HN-C(O)-C(O)-NH)Py2Br2] · H2O, and [Pt(en)PyBr3]NO3
摘要:
Heating of an aqueous solution of [Pt(en)Py2Cl2]Cl-2 center dot 2H(2)O (I) with a KBr excess leads to the formation of [Pt(en)Py2Br2]Br-2 center dot H2O (II). The interaction of a solution of II with bromine water results in the presipitation of polybromide ([Pt(en)Py2Br2] Br-2 center dot Br-2), which within a few days in the reaction solution partly transforms into oximide platinum(IV) complex, [Pt(HN - C(O)-C(O)-NH)Py2Br2] center dot H2O (III). Complex [Pt(en)PyBr3]Br center dot H2O (IV) with an impurity of II was prepared by reacting KBr excess and the product of a Pt(en)Py-2]Cl-2 oxidation with chlorine in 0.05 N HCl. The action of HNO3 on the solution of IV produced a nitrate derivative ([Pt(en)PyBr3]NO3, V). Complex IV, unlike II does not react woth bromine. The IR spectra of all the obtained compounds were recorded. Complexes II,III, and V were studies by X-ray crystallography. The crystals of II are monoclinic, space group P2(1)/c, a = 15.640(2) angstrom, b = 9.345(1) angstrom, c = 14.167(2) angstrom, beta = 102.63(1)degrees, V = 2020.5(5), angstrom(3), Z = 4, R-hkl = 0.033. The crystals of III are triclinic, space group P (1) over bar , a = 7.108(1)angstrom, b = 10.946(1) angstrom, c = 11.020(2) angstrom, alpha = 83.63(1)degrees, beta = 80.31(1)degrees, gamma = 75.02(1)degrees, V = 814.4(2) angstrom(3), Z = 2, R-hkl = 0.033. In the near-planar five-membered chelate ring (torsion angle NCCN is 7 degrees), the C-O distances (1.23(1)angstrom) correspond to double bonds; the C-C (1.53(1)angstrom) and C-N (1.31(1)angstrom), distances correspond to ordinary bonds. The crystals of V are monoclinic, space group P2(1)/c, a = 8.306(2) angstrom, b = 8.995(2) angstrom, c = 20.231 (4) angstrom, beta = 97.48(2)degrees, V = 1498.6(6) angstrom(3), Z = 4, R-hkl = 0.037.