Portal de Periódicos da CAPES

Synthesis and X-ray crystal structures of the one-dimensional ribbon chains [MOBut·ButOH]∞ and the cubane species [MOBut]4 (M = K and Rb)

1991; Elsevier BV; Volume: 10; Issue: 3 Linguagem: Inglês

10.1016/s0277-5387(00)80154-0

1873-3719

Malcolm H. Chisholm, Simon R. Drake, Ahmad A. Naiini, William E. Streib,

Polyoxometalates: Synthesis and Applications

The series [MOBut·ButOH]∞ (M = K, Rb and Cs) have been prepared by the reaction of M with ButOH in THF. Single-crystal X-ray diffraction studies revealed for M = K or Rb that [MOBut·ButOH]∞ crystallizes from tetrahydrofuran-n-pentane at −20°C in the triclinic space group P1, with unit cell dimensions [K, Rb]: a = 9.862(3), 9.886(2) Å; b = 9.929(4), 9.914(2) Å; c = 6.330(2), 6.640(1) Å; β = 90.66(2), 90.46(1)° 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 Å) also results in a near linear O(7)HO(2) angle (167.4, 172.61°) with the hydrogen atom closer to O(7) (1.22, 1.18 Å), than O(2) (1.24, 1.27 Å). These alcohol adducts may be readily converted into the compounds [MOBut]4 (M = K, Rb and Cs) by sublimation. Single-crystal X-ray diffraction studies reveal for M = K or Rb, that [MOBut]4 crystallizes from toluene at −20°C in the cubic space group P43M; with unit cell dimensions [K, Rb]; a = 8.372(1), 8.514(1) Å, and Z = 4, as cubane structures. Within the cubane-like structures the OMO angles are found to deviate only slightly from 90°, with OMO (90.18, 89.11°) and MOM (89.82, 90.89°) for M = K and Rb, respectively. The alcohol adducts undergo an alkoxide ligand exchange process that is rapid on the 1H NMR time scale at room temperature.