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(SiMe3)3; N,C = CH2SiMe2N(SiMe3)] which was quite inert toward I, the anionic bismetallacycle [NaUN*(N,C)(2)] (2) was readily transformed into the enlarged monometallacycle [UN*(N,N)I] (4) [N,N = (Me3Si)NSiMe2CH2CH2SiMe2N(SiMe3)] resulting from C-C coupling of the two CH2 groups, and [NaUN*(N,O)(2)] (3) [N,O = OC(=CH2)SiMe2N(SiMe3)], which is devoid of any U-C bond, was oxidized into the U-v bismetallacycle [Na{UN*(N,O)(2)}mu-I] (5). Sodium amalgam reduction of 4 gave the U-III compound [UN*(N,N)] (6). Addition of MN3 or MCN to the (N,C), (N,N), and (N,O) metallacydes 1, 4, and 5 led to the formation of the anionic azide or cyanide derivatives M[UN*(2)(N,C)(N-3)] [M = Na, 7a or Na(15-crown-5), 7b], M[UN*(2)(N,C)(CN)] [M = NEt4, 8a or Na(15-crown-5), 8b or K(18-crown-6), 8c], M[UN*(N,N)(N-3)(2)] [M = Na, 9a or Na(THF)(4), 9b], [NEt4][UN*(N,N)(CN)(2)] (10), M[UN*(N,O)(2)(N-3)] [M Na, 11a or Na(15-crown-5), 11b], M[UN*(N,O)(2)(CN)] [M = NEt4, 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 I la was transformed into the neutral U-v complex [U(N{SiMe3}SiMe2C{CHI}O)(2)I(THF)] (13). The X-ray crystal structures of 4, 7b, 8a-c, 9b, 10, 12b, and 13 were determined.