PHOTOPHYSICAL PROPERTIES, ELECTROCHEMISTRY AND CRYSTAL-STRUCTURE OF NITRIDOOSMIUM(VI) COMPLEXES OF 2,3-DIAMINO-2,3-DIMETHYLBUTANE

The complex [OsN(H2L)2Cl]Cl2.2H2O 1 was prepared by the reaction of [NBu4][OsNCl4] with 2,3-diamino-2,3-dimethylbutane (H-2L) in methanol. Treatment of 1 with CF3SO3H under argon gave [OsN-(H2L)2][CF3SO3]3 2 which on prolonged standing in acetonitrile yielded [OsN(HL)(H2L)2][CF3SO3]2 3. The crystal structures of 1 and 3 have been determined by X-ray crystallography: 1, triclinic, space group, P1BAR (no. 2), a = 7.176(1), b = 7.273(2), c = 10.823(2) angstrom, alpha = 101.20(2), beta = 106.88(2), gamma = 97.96(2)degrees, Z = 1; 3, monoclinic, space group, C2/c (no. 15), a = 15.810(3), b = 12.766(3), c = 16.225(4) angstrom, beta = 110.25(2)degrees, Z = 4. The emission spectrum of 1 at 77 K shows vibrational progression with spacing of 1050 cm-1 characteristic of the ground-state nu(Os=N) stretch. In 0.1 mol dm-3 CF3CO2H the cyclic voltammogram of 2 displays a 3H+-3e- reduction wave at -0.34 V vs. saturated calomel electrode assignable to the reduction of Os(VI)=N to OsIII-NH3.