Iodide, azide, and cyanide complexes of (N,C), (N,N), and (N,O) metallacycles of tetra- and pentavalent uranium

In contrast to the neutral macrocycle UN*(2)(N,C)] (1) N* = N(SiMe(3))(3); N,C = CH(2)SiMe(2)N(SiMe(3))] which was quite inert toward I(2), the anionic bismetallacycle NaUN*(N,C)(2)] (2) was readily transformed into the enlarged monometallacycle UN*(N,N)I] (4) N,N = (Me(3)Si)NSiMe(2)CH(2)CH(2)SiMe(2)N(SiMe(3))] resulting from C-C coupling of the two CH(2) groups, and NaUN*(N,O)(2)] (3) N,O = OC(═CH(2))SiMe(2)N(SiMe(3))], which is devoid of any U-C bond, was oxidized into the U(V) bismetallacycle Na{UN*(N,O)(2)}(2)(μ-I)] (5). Sodium amalgam reduction of 4 gave the U(III) compound UN*(N,N)] (6). Addition of MN(3) or MCN to the (N,C), (N,N), and (N,O) metallacycles 1, 4, and 5 led to the formation of the anionic azide or cyanide derivatives MUN*(2)(N,C)(N(3))] M = Na, 7a or Na(15-crown-5), 7b], MUN*(2)(N,C)(CN)] M = NEt(4), 8a or Na(15-crown-5), 8b or K(18-crown-6), 8c], MUN*(N,N)(N(3))(2)] M = Na, 9a or Na(THF)(4), 9b], NEt(4)]UN*(N,N)(CN)(2)] (10), MUN*(N,O)(2)(N(3))] M = Na, 11a or Na(15-crown-5), 11b], MUN*(N,O)(2)(CN)] M = NEt(4), 12a or Na(15-crown-5), 12b]. In the presence of excess iodine in THF, the cyanide 12a was converted back into the iodide 5, while the azide 11a was transformed into the neutral U(V) complex U(N{SiMe(3)}SiMe(2)C{CHI}O)(2)I(THF)] (13). The X-ray crystal structures of 4, 7b, 8a-c, 9b, 10, 12b, and 13 were determined.