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 (H2L) in methanol. Treatment of 1 with CF3SO3H under argon gave [OsN(H2L)2][CF3SO3]32 which on prolonged standing in acetonitrile yielded [OsN(HL)(H2L)2][CF3SO3]23. The crystal structures of 1 and 3 have been determined by X-ray crystallography: 1, triclinic, space group, P(no. 2), a= 7.176(1), b= 7.273(2), c= 10.823(2)Å, α= 101.20(2), β= 106.88(2), γ= 97.96(2)°, Z= 1; 3, monoclinic, space group, C2/c(no. 15), a= 15.810(3), b= 12.766(3), c= 16.225(4)Å, β= 110.25(2)°, Z= 4. The emission spectrum of 1 at 77 K shows vibrational progression with spacing of 1050 cm–1 characteristic of the ground-state ν(OsN) 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 OsVIN to OsIII–NH3.