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, P1 (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-1characteristic of the ground-state ν(Os≡N) stretch. In 0.1 mol dm-3CF3CO2H the cyclic voltammogram of 2 displays a 3H+-3e-reduction wave at -0.34 V vs. saturated calomel electrode assignable to the reduction of OsVI≡N to OsIII-NH3.