SYNTHESIS AND X-RAY CRYSTAL-STRUCTURES OF THE ONE-DIMENSIONAL RIBBON CHAINS [MOBUT.BUTOH]-INFINITY AND THE CUBANE SPECIES [KOBU(T)]4 AND [RBOBUCT)]4

The series [MOBu(t).Bu(t)OH]infinity (M = K, Rb and Cs) have been prepared by the reaction of M with Bu(t)OH in THF. Single-crystal X-ray diffraction studies revealed for M = K or Rb that [MOBu(t).Bu(t)OH]infinity crystallizes from tetrahydrofuran-n-pentane at -20-degrees-C in the triclinic space group P1BAR, with unit cell dimensions [K, Rb]: a = 9.862(3), 9.886(2) angstrom; b = 9.929(4), 9.914(2) angstrom; c = 6.330(2), 6.640(1) angstrom; beta = 90.66(2), 90.46(1)-degrees and Z = 2, as a one-dimensional chain linked by hydrogen-bonding. The strong hydrogen-bonding within the chain O(2)-O(7) (2.46, 2.44 angstrom) also results in a near linear O(7)-H-O(2) angle (167.4, 172.61-degrees) with the hydrogen atom closer to O(7) (1.22, 1.18 angstrom), than O(2) (1.24, 1.27 angstrom). These alcohol adducts may be readily converted into the compounds [MOBu(t)]4 (M = K, Rb and Cs) by sublimation. Single-crystal X-ray diffraction studies reveal for M = K or Rb, that [MOBu(t)]4 crystallizes from toluene at -20-degrees-C in the cubic space group P4BAR3M; with unit cell dimensions [K, Rb]; a = 8.372(1), 8.514(1) angstrom, and Z = 4, as cubane structures. Within the cubane-like structures the O-M-O angles are found to deviate only slightly from 90-degrees, with O-M-O (90.18, 89.11-degrees) and M-O-M (89.82, 90.89-degrees) for M = K and Rb, respectively. The alcohol adducts undergo an alkoxide ligand exchange process that is rapid on the H-1 NMR time scale at room temperature.