Reaction of ThBr4(THF)(4) with 4 equiv of potassium diphenylamide in THF produces the THF adduct Th(NPh(2))(4)(THF)(1) in 61% yield. Use of 4 or 5 equiv of the less bulky potassium N-methylanilide in an analogous reaction allows the isolation of the bis-THF adduct Th(NMePh)(4)(THF)(2) (2) or the salt K[Th(MePh)(5)] (3), respectively. The trans amination reaction of the metallacycle {[(Me(3)Si)(2)N]Th-2(CH(2)SiMe(2)NSiMe(3))} with 4 equiv of N-methylaniline in refluxing toluene produces the four-coordinate amide species Th[N(SiMe(3))(2)](2)(NMePh)(2) (4). An X-ray crystal structure determination of 4 revealed a distorted tetrahedral environment about the metal center, with Th-N distances averaging 2.308(7) Angstrom. Close approach of the methyl groups within the N-methylanilide ligands to the metal center is suggestive of an agostic interaction, with Th-C distances of 3.073(10) and 3.064(10) Angstrom. Crystal data for 4 (at -70 degrees C) : monoclinic space group P2(1)/c, a = 17.091(3) Angstrom, b = 11.825(2) Angstrom, 16.981(3) Angstrom, beta = 90.23(3)degrees, V = 3431.9 Angstrom(3), Z = 4, d(calc) = 1.481 g cm(-3), R(F) = 0.0378, R(w)(F) = 0.0391.