Reaction of the thorium(IV) metallacycle [(Me3Si)2N]2Th(CH2SiMe2NSiMe3) with 4 equiv of 2-propanol in toluene generates a homoleptic thorium isopropoxide [Th(O-i-Pr4]x (1) in good yield. In contrast, the reaction of the thorium metallacycle with 4 equivalents of 2-propanol in toluene, followed by the addition of excess pyridine and crystallization from hexane, yields the tetrameric complex Th4(O-i-Pr)16(py)2 (2). However, if compound 1 is allowed to "age" for 2 days, no reaction with pyridine and the aged material is observed. Compound 2 may also be prepared by the metathesis reaction of ThBr4(THF)4 with 4 equiv of potassium isopropoxide in THF followed by the addition of excess pyridine. An X-ray crystal structure of 2 revealed a zigzag chain of four thorium atoms comprised of a dimer of edge-shared bioctahedra joined by one axial and one equatorial bridging alkoxide ligand. The local coordination geometry about each thorium atom is that of a distorted octahedron, and the thorium atoms at each end of the zigzag chain are capped with a pyridine ligand. Average terminal and bridging Th-O distances are 2.172 and 2.420 angstrom. The Th-N distance is 2.740 angstrom, and nonbonding Th--Th distances average 4.031 angstrom. A similar reaction between [(Me3Si)2N]2Th(CH2SiMe2NSiMe3) and 4 equiv of pentan-3-ol in toluene followed by addition of excess pyridine and crystallization from hexane yields the dimeric complex Th2(OCHEt2)8(py)2 (3). An X-ray crystal structure of 3 revealed a centrosymmetric edge-sharing bioctahedron with average Th-O, Th-mu-O, Th-N, and Th--Th distances of 2.170, 2.427, 2.730, and 4.055 angstrom, respectively. Crystal data for 2 (at - 170-degrees-C) : Triclinic space group P1BAR, a = 11.211(2) angstrom, b = 18.689(4) angstrom, c = 9.984(2) angstrom, alpha = 101.65(1)-degree, beta = 108.57(1)-degree, gamma = 75.60(1)-degree, V = 1903.52 angstrom3, Z = 1, d(calc) = 1.772 g cm-3, R(F) = 0.0441, R(w)(F) = 0.0453. Crystal data for 3 (at -70-degrees-C) : Triclinic space group P1BAR, a = 11.302(3) angstrom, b = 11.458(3) angstrom, c = 14.191(3) angstrom, alpha = 113.02(2)-degrees, beta = 92.50(2)-degrees, gamma = 115.82(2)-degrees, V = 1470.9 angstrom3, Z = 1, d(calc) = 1.345 g cm-3, R(F) = 0.0448, R(w)(F) = 0.0498.