KZr2(O(t)Bu)(9) was prepared by reaction of KO(t)Bu with Zr(O(t)Bu)(4) in a 1:2 molar ratio. Attempted sublimation results in dissociation of Zr(O(t)Bu)(4), affording [KZr(O(t)Bu)(5)](n), which can also be synthesized using equimolar KO(t)Bu and Zr(O(t)Bu)(4). Single-crystal X-ray diffraction revealed that n = 2; K2Zr2(O(t)Bu)(10) crystalizes from pentane at -20 degrees C in the monoclinic space group P2(1)/c, with the unit cell dimensions a = 10.532(1) Angstrom, b = 18.057(3) Angstrom, c = 27.618(5) Angstrom, beta = 95.54(1)degrees, and Z = 4. The dimer is composed of two five-coordinate Zr centers, each having trigonal bipyramidal geometry; the axes of the trigonal bipyramids are orthogonal, and the Zr(O(t)Bu)(5)(-) units encapsulate both potassiums. Due to fluxionality, this species appears as a singlet in H-1 NMR in d(8)-toluene even at -75 degrees C. Interconversions between and possible dissociative reactions of KZr2(O(t)Bu)(9) and [KZr(O(t)Bu)(5)](2) are also tested experimentally.